Clinical and imaging features of adult influenza B viral pneumonia / 中国医师杂志

Objective:To analyze the clinical and imaging characteristics of adult patients with influenza B viral pneumonia and improve the understanding of influenza B viral pneumonia in clinicians.Methods:The clinical data of adult patients with influenza B virus pneumonia were collected from January 2021 to December 2022 in the fever clinic of Beijing Hospital of Traditional Chinese Medicine affiliated to Capital Medical University. The clinical symptoms, blood routine results and lung computed tomography (CT) results were analyzed and summarized.Results:The clinical data of 24 adult patients with influenza B virus pneumonia were collected. The time from onset to treatment was (2.7±0.3)d. All patients had fever, and 14 of them had body temperature >39 ℃. Blood routine and procalcitonin levels were normal, while C-reactive protein levels were elevated [(56.28±32.35)mg/L]. Oxygen saturation was normal (≥95%). The pulmonary CT findings were mostly small flake ground glass shadows distributed on one side, and some of them were cord shadows caused by interstitial lesions.Conclusions:Influenza B virus infection can also cause pneumonia, but is relatively limited and has a good prognosis.

Phylogenetic and antigenic analysis of HA gene of influenza virus B (Victoria) in Beijing during 2021-2022 surveillance season / 中华微生物学和免疫学杂志

Objective:To investigate the phylogenetic and antigenic characteristics of hemagglutinin (HA) gene of influenza B/Victoria lineage (BV) viruses in Beijing during the 2021-2022 influenza surveillance season, and to analyze whether the circulating BV viruses match the vaccine strain.Methods:Pharyngeal swab specimens from influenza like-illness (ILI) cases in the 2021-2022 influenza surveillance season were collected from surveillance network labs in Beijing and cultured in MDCK cells and chicken embryo to isolate BV viruses. Nucleic acids of the viruses were extracted, and the HA gene was amplified and sequenced. The nucleotide and amino acid sequence identity of the HA gene was analyzed using MEGA5.0 software. A phylogenetic tree of HA gene was constructed using the maximum likelihood method. The N-glycosylation sites in HA were predicted online. Three-dimensional structure of HA was constructed using SWISS-MODEL homologous modeling. Hemagglutination inhibition (HI) test was performed to analyze the antigenicity of BV viruses.Results:A total of 402 BV viruses were collected and 58 strains with full-length HA gene sequences were chosen for further analysis. Compared with the HA gene of this year′s vaccine strain (B/Washington/02/2019), there were 27 amino acid mutations, 11 of which were located in four different antigenic determinants. The phylogenetic analysis revealed that three subgroups of 1A.3, 1A.3a1, and 1A.3a2 co-circulated in Beijing with 54 strains (54/58, 93.10%) clustered to the Clade 1A.3a2, two strains (2/58, 3.45%) clustered to the Clade 1A.3a1, and two strains (2/58, 3.45%) in the same subgroup (Clade 1A.3) as the vaccine component BV strain in 2021-2022. Compared with the vaccine strain (B/Washington/02/2019), two BV strains had an additional N-glycosylation site at residue 197, while the other 56 strains showed no change in N-glycosylation sites. Antigenic analysis showed that 35 BV strains (35/58, 60.34%) were antigenically similar to the vaccine strain and 23 strains (23/58, 39.66%) were low-response strains.Conclusions:Three subgroups of BV viruses co-circulated in Beijing during the 2021-2022 influenza surveillance season. The predominant subgroup was Clade 1A.3a2 (93.10%), showing a certain genetic distance with the vaccine strain (B/Washington/02/2019). Nearly 40% (39.66%) of the viruses were low-response strains. This study indicated that continuous monitoring of the variations of influenza epidemic strains and timely providing laboratory basis for screening vaccine component strains were the basic technical guarantee for coping with influenza pandemic.

Genomic characterization of seven reassortant influenza B viruses in Hangzhou, China / 中华微生物学和免疫学杂志

Objective:To analyze the prevalence of influenza B virus in Hangzhou from 2014 to 2020 and the genetic evolution of seven reassortant strains of influenza B virus.Methods:Influenza viruses were isolated from throat swabs collected from 16 943 patients with influenza-like illness in Hangzhou from January 2014 to December 2020. The subtypes of influenza viruses were identified by real-time RT-PCR. Eight genes ( PB2, PB1, PA, HA, NP, NA, MP and NS) of influenza B viruses were amplified with specific primers and then analyzed with nanopore sequencing and phylogenetic analysis. Results:From January 2014 to December 2020, there were 1 090 influenza B virus-positive samples, including 474 samples of Yamagata lineage and 616 samples of Victoria lineage, were identified in Hangzhou with an overall positive rate of 6.43% (1 090/16 943). Whole genomes of 228 strains of influenza B virus were obtained by nanopore sequencing and seven reassortant strains of influenza B virus were found. There were four reassortant influenza B viruses of Yamagata lineage with NA gene fragments from viruses of Victoria lineage, two strains of Yamagata lineage (H644_BY and H648_BY) with NP and NA gene fragments from Victoria lineage and one strain of Victoria lineage with PB2, PB1, PA and NS gene fragments from Yamagata lineage. Meanwhile, these seven strains possessed several mutations in the antigenic sites of HA and NA genes. Conclusions:Several rare reassortant strains of influenza B virus with epidemic potential were detected in Hangzhou from 2014 to 2020, which indicated that the traditional detection methods should be improved and more attention should be paid to the reassortant influenza B viruses and the match between epidemic and vaccine strains.

Innate immune response mediated by interferon during influenza B virus infection / 中国生物制品学杂志

@#ObjectiveTo explore the innate immune response mediated by interferon(IFN) induced by influenza B virus(IBV)infection.MethodsThe activation of IFN signaling pathway and the expression of IFN-stimulated genes were detected by qPCR using Madin Darby canine kidney(MDCK)cells infected with IBV as model. The supernatants of MDCK cells infected with IBV for 36 h and 48 h were collected and mixed with fresh medium to culture MDCK cells infected with IBV. The antiviral effect of endogenous IFN was detected by qPCR. After adding JAK-STAT pathway inhibitor CP,the supernatant of IBV infected MDCK cells was collected and the cells were cultured. The effect of JAK-STAT pathway inhibition on the antiviral effect of endogenous IFN was detected by qPCR.ResultsIBV effectively activated IFN signal pathway and induced the production of cytokines dominated by typeⅠIFN(IFNα,IFNβ)and typeⅢIFN(IFNλ1,IFNλ3).Meanwhile,MDCK cells infected with IBV induced a series of IFN-stimulated genes(ISGs)with broad-spectrum antiviral effect,such as ISG15,CCL5,CXCL10,MX1 and RIG-I. After CP was used to inhibit JAK-STAT pathway,the ability of ISGs production induced by IBV infection in MDCK cells and the corresponding antiviral effect were significantly inhibited.ConclusionMDCK cells infected with IBV effectively activated type Ⅰ and type Ⅲ IFN mediated JAK-STAT signaling pathways,which provided a reference for the further understanding the interaction between IBV and host.

Síndrome Respiratória Aguda Grave por Influenza A/B: Análise da Situação Vacinal / Severe Acute Respiratory Syndrome due to Influenza A/B: Analysis of Vaccination Status

Introdução: A Influenza é uma doença respiratória altamente contagiosa, prevenível por vacinação, afetando todos os grupos etários,com morbidade e mortalidade variáveis. O objetivo deste estudo foi analisar a relação da situação vacinal dos pacientes com Influenza A/B atendidos com Síndrome Respiratória Aguda Grave. Métodos: Estudo retrospectivo, a partir das notificações do Sistema de Informação de Agravos de Notificação Compulsório do Brasil, de pacientes com esquema vacinal conhecido para Influenza A/B em um hospital-escola do interior do Rio Grande do Sul (2012 a 2018). Resultados: Foram incluídos 596 casos de SRAG, sendo 179 (30,0%) por vírus respiratórios [92 (51,4%) Influenza A/B e 87 (48,6%) outros vírus respiratórios]. Na faixa etária de maiores de 50 anos, a frequência foi 28,2%, 6 meses a 1 ano foi de 19,6%, seguido de 13% no grupo etário de 2 a 4 anos. O esquema vacinal estava completo em 59,8% dos casos, sendo que em 37,5% dos pacientes apresentavam esquema vacinal incompleto. O tratamento antiviral foi administrado em 90,2% do pacientes com SRAG por Influenza A/B, e a alta hospitalar ocorreu em 91,3% dos casos. Conclusão: A vacinação é uma estratégia para prevenção de complicações relacionadas à Influenza. No entanto, a SRAG é uma apresentação com diagnóstico diferencial amplo, e as causas virais necessitam de confirmação para uma otimização da terapêutica antiviral. A equipe de saúde deve estar atenta a pacientes com riscos de SRAG, a fim de minimizar os desfechos negativos, mesmo nos vacinados.

Introduction: Influenza is a highly contagious respiratory disease, preventable by vaccination, affecting all age groups, with variable morbidity and mortality. The objective of this study was to analyze the relationship between the vaccination status of Influenza A/B patients seen with Severe Acute Respiratory Syndrome. Methods: Retrospective study, from notifications of the Brazilian Compulsory Notification Agencies Information System (Sistema de Informação de Agravos de Notificação Compulsório do Brasil), of patients with known vaccination schemes for Influenza A/B in a teaching hospital in the interior of Rio Grande do Sul (2012 to 2018). Results: Of the 596 cases of SARS included, 179 (30.0%) were due to respiratory viruses [92 (51.4%) Influenza A/B and 87 (48.6%) other respiratory viruses]. In the age group over 50 years, the frequency was 28.2%, from 6 months to 1 year old was 19.6%, followed by 13% in the age group of 2 to 4 years. The vaccination schedule was complete in 59.8% of cases, with 37.5% having an incomplete vaccination scheme. Antiviral treatment was administered in 90.2% of the patients with SARS by Influenza A/B, and hospital discharge occurred in 91.3% of the cases. Conclusion: Vaccination is a strategy to prevent complications related to Influenza. However, SARS is a presentation with wide differential diagnosis, and the viral causes need confirmation for an optimization of the antiviral therapy. The healthcare team must be aware of patients at risk of SARS to minimize negative outcomes, even in vaccinated patients.

Plataforma laboratorial para monitorear el SARS-CoV-2 basada en la vigilancia de influenza y otros virus respiratorios en Perú / Laboratory platform for monitoring SARS-CoV-2 based on surveillance of influenza and other respiratory viruses in Peru

RESUMEN En el Perú, la pandemia de la COVID-19 ha evidenciado la utilidad de tener un sistema de vigilancia laboratorial estructurado y en funcionamiento desde hace 22 años, basado en la vigilancia de influenza; inicialmente en modalidad de unidades centinela, y después fortaleciéndose e innovándose, con recursos propios y con apoyo externo, para generar información de calidad. Se han implementado avances biotecnológicos para la confirmación diagnóstica e incrementado las capacidades de la red nacional de laboratorios, manteniendo la eficiencia, considerando las diversas y complejas realidades de los niveles regionales, y superando dificultades de comunicación y articulación entre instituciones. Resulta necesario consolidar este sistema, con trabajo colaborativo y coordinado entre sus componentes, impulsando su eficacia y oportunidad y promoviendo la vigilancia genómica de nuevos virus y variantes, como actualmente ocurre con el SARS-CoV-2.

ABSTRACT In Peru, the COVID-19 pandemic demonstrated the usefulness of having a structured laboratory surveillance system that has been operational for 22 years, based on influenza surveillance; initially in the form of sentinel units, and later strengthened and innovated, with its own resources and with external support, to provide quality information. Biotechnological advances have been implemented for diagnostic confirmation and the capacity of the national laboratory network has been expanded, maintaining efficiency, considering the diverse and complex realities of each region, and overcoming difficulties regarding communication and articulation between institutions. It is necessary to consolidate this system, with collaborative and coordinated work between its components, boosting its effectiveness and timeliness and promoting genomic surveillance of new viruses and variants, as is currently the case with SARS-CoV-2.

Analysis of clinical characteristics of influenza virus pneumonia and risk factors for severe pneumonia in 711 Children / 国际儿科学杂志

Objective:To investigate the clinical characteristics of influenza A and influenza B pneumonia and the risk factors of severe influenza pneumonia in children.Methods:The epidemiology, clinical characteristics, laboratory tests and pathogens of co-infection in children with pneumonia caused by influenza A virus and influenza B virus, and the risk factors of severe influenza pneumonia were retrospectively analyzed.Results:(1) The cases of influenza A infection accounted for 65.1% and those with influenza B infection accounted for 32.9% among the 711 children with influenza pneumonia.The dominant strain was Influenza B Victoria virus in spring and summer, influenza A(H 3N 2) virus in autumn, and influenza A(H1N1) virus in winter.The dominant strain was influenza A virus at the age of < 1 year and ~3 years, influenza A virus and influenza B virus at the age of ~6 years, and influenza B virus at the age of ≥6 years.(2) The gastrointestinal symptoms were more common in children with influenza B pneumonia compared with those with influenza A pneumonia(53.4% vs 44.7%, χ2=4.728, P=0.030), but crackles and wheezing were more common in children with influenza A pneumonia compared with those with influenza B pneumonia(80.1% vs 70.5%, 36.9% vs 25.6%, χ2=8.945, 8.093, all P<0.05). (3) The percentage of decreased lymphocyte count in children with influenza B pneumonia was higher than those with influenza A pneumonia(5.6% vs 1.9%, χ2=6.633, P=0.010). (4) Mixed Mycoplasma Pneumoniae was more common in children with influenza B pneumonia compared with those with influenza A pneumonia(23.9% vs 10.8%, χ2=20.789, P<0.001), and mixed virus and bacteria were more common in children with influenza A pneumonia compared with those with influenza B pneumonia(15.8% vs 8.1%, 50.1% vs 41.9%, χ2=7.934, 4.221, all P<0.05). (5) Multivariate logistic regression analysis showed that age <2 years( OR=1.886, 95% CI 1.149~3.096, P=0.012), increased LDH( OR=1.736, 95% CI 1.080~2.790, P=0.023), the percentage of lymphocyte decreased( OR=2.762, 95% CI 1.669~4.571, P<0.001) and the percentage of CD3 + decreased ( OR=6.019, 95% CI 3.993~9.331, P<0.001)were risk factors for severe influenza pneumonia. Conclusion:Among hospitalized children with influenza pneumonia, there were some differences in the age of infection, clinical characteristics, laboratory tests and pathogens of co-infection between the cases caused by influenza B and influenza A, and clinicians should remain vigilant for the occurrence of severe influenza pneumonia.

Genetic evolution of influenza B virus in Guizhou Province during 2017 to 2021 / 中华微生物学和免疫学杂志

Objective:To analyze the molecular evolution characteristics of HA and NA genes of influenza B/Yamagata (BY) and influenza B/Victoria (BV) lineage viruses in Guizhou Province, aiming to provide reference for scientific prevention and control of influenza. Methods:The prevalence of various types of influenza viruses in Guizhou Province from 2017 to 2021 was analyzed. The nucleic acid of influenza B viruses was extracted, and then the HA and NA genes were amplified by RT-PCR. Fourteen strains were sequenced and the sequences of 83 strains were obtained from GISAID. Homologies between the 97 influenza B viruses as well as the phylogenetic characteristics and amino acid site variations were analyzed. Results:Influenza A, BY and BV lineage viruses co-circulated in Guizhou Province and BV lineage was the predominant type. The homologies of HA and NA genes were 98.7%-99.4% and 98.4%-99.6% between BY lineage viruses and the reference vaccine strain B/PHUKET/3073/2013. BV lineage viruses shared 98.3%-99.3% and 98.9%-99.6% homologies with the reference vaccine strain B/Colorado/06/2017. The BY lineage strains in Guizhou Province mainly belonged to Y3 genetic group with HA gene in two branches of Y3-H1-2 and NA gene in three branches of Y3-N1-3. Three reassortant strains were found in Y3 clade. The isolated BV lineage strains mainly belonged to V1A-2 genetic group with HA gene in four branches of V1A-2 H1-4 and NA gene in five branches of V1A-2 N1-5. Twenty reassortant strains were found in V1A-2 clade and no inter-lineage reassortants were found. Analysis of variations at key amino acid sites showed that there was no mutation at epitopes in Y3 genetic group. However, there were point mutations at four main epitopes and a shift mutation in 190 helix in V1A-2 genetic group. There was no mutation in drug resistance sites. Conclusions:Various types of influenza viruses circulated in Guizhou Province. The homology between influenza B viruses and vaccine strains was decreasing. Different branches of HA and NA genes had been evolved and various forms of mutations were detected in the sequences. Intra-lineage reassortant strains and new varieties emerged. Surveillance of influenza B viruses should be strengthened.

Rapid Molecular Point of Care Testing for Detection of Influenza A, B Viruses and Respiratory Syncytial Virus Versus Multiplex PCR

@#Introduction: Rapid detection of influenza viruses and respiratory syncytial virus (RSV) can be achieved by having rapid molecular point of care tests (POCTs). This expedites the diagnosis attributed by having similar clinical presentations leading to facilitation of precision medicine and reduction of antimicrobial resistance. The growing number of POCTs foster the need to ensure that these POCTs have satisfactory and reliable performance. With that the aim of this study is to evaluate the performance of rapid molecular POCT regarded as ‘X’ for the detection of Influenza viruses and RSV in comparison to multiplex PCR. Methods: A laboratory-based study was conducted from January to December 2020 which involved analysis of 116 nasopharyngeal swabs, tested using POCT X and multiplex PCR as a method of reference. The performance analysis incorporated the sensitivity, specificity, positive and negative predicted values determination. The cycle threshold values were reviewed for discordant results. Results: The POCT X demonstrated sensitivity of 88.57% with 100% specificity for Influenza A virus, and 85.71% of sensitivity with 100% specificity for influenza B virus detection. Meanwhile it revealed 100% sensitivity and specificity for RSV detection. There were ten specimens demonstrating discordant results whereby viruses were not detected by POCT X, however detected by multiplex PCR. The POCT X was not able to detect eight (12.9%) and two (16.7%) influenza A and B viruses respectively. Conclusion: The overall performance of POCT X was corresponded to multiplex PCR. This best served as a steadfast ancillary test for influenza and RSV infection.

Expression of influenza B virus hemagglutinin and its immunogenicity determination / 生物工程学报

Influenza B virus is one of the causes for seasonal influenza, which can account for serious illness or even death in some cases. We tested the expression of extracellular domain of hemagglutinin (HA-ecto) of influenza B viruses in mammalian cells, and then determined the immunogenicity of HA-ecto in mice. The gene sequence encoding influenza B virus HA-ecto, foldon sequence, and HIS tag was optimized and inserted into pCAGGS vector. The opening reading frame (ORF) of neuraminidase was also cloned into pCAGGS. The pCAGGS-HA-ecto and pCAGGS-NA were co-transfected into 293T cells using linear polyethylenimine. Cell supernatant after transfection was collected after 96 h, and the secreted trimmeric HA-ecto protein was purified by nickel ion affinity chromatography and size exclusion chromatography. Subsequently, the mice were immunized with HA-ecto protein, and the corresponding antibody titers were detected by ELISA and hemagglutination inhibition (HAI) assays. The results showed that soluble trimeric HA-ecto protein could be obtained using mammalian cell expression system. Moreover, trimeric HA-ecto protein, in combination with the adjuvant, induced high levels of ELISA and HAI antibodies against homogenous and heterologous antigens in mice. Thus, the soluble HA-ecto protein expressed in mammalian cells could be used as a recombinant subunit vaccine candidate for influenza B virus.

Muerte súbita por miocarditis aguda asociada al virus influenza tipo B. Reporte de un caso / Sudden death due to acute myocarditis associated with influenza type B virus. Case report

Resumen La miocarditis es una inflamación del miocardio causada principalmente por infecciones virales, dentro de las cuales se encuentra el virus Influenza tipo B. Su presentación clínica varía desde individuos asintomáticos o con síntomas leves e inespecíficos a una miocarditis fulminante e incluso muerte súbita. La principal consecuencia a largo plazo es una miocardiopatía dilatada con insuficiencia cardiaca. Se presenta el caso de una femenina de 17 años, sin patologías crónicas conocidas, la cual presentó un cuadro viral de dos días de evolución y luego falleció de manera súbita; en la autopsia médico legal se documentó mediante estudios histopatológicos una miocarditis linfocítica aguda y por medio de la técnica de reacción en cadena de la polimerasa (PCR) de un frotis traqueal se evidenció la presencia del virus influenza tipo B. Se realizó una revisión de la literatura sobre miocarditis principalmente miocarditis viral causada por el virus Influenza B.

Abstract Myocarditis is an inflammatory disease of the heart muscle. Viral infections are the most frequent cause of myocarditis, incluided Influenza B virus. The clinical presentation of acute miocarditis is highly variable, ranging from subclinical disease to fulminant heart failure and sometimes with sudden death. The major long term consequence is dilated cardiomyopathy with chronic heart failure. We present a case of a 17 years old woman who presented with viral symptoms for two days and then died suddenly; in the medico-legal autopsy, an acute lymphocytic myocarditis was documented through histopathological studies and the presence of influenza type B virus was evidenced by means of the polymerase chain reaction (PCR) technique of a tracheal smear. A review of the literature on myocarditis, mainly viral miocarditis caused by the Influenza B virus, was made.

Infecção por Influenza B e doença de Kawasaki em adolescente durante a pandemia da COVID-19: relato de caso / Influenza B infection and Kawasaki disease in an adolescent during the COVID-19 pandemic: a case report

RESUMO Apresentação de um caso de infecção por Influenza B e doença de Kawasaki em adolescente ocorrido durante a pandemia da COVID-19. Adolescente asmática evoluiu com febre e síndrome gripal por 7 dias e deu entrada com quadro de insuficiência respiratória aguda, necessitando de intubação orotraqueal. Evoluiu também com instabilidade hemodinâmica respondedora ao uso de droga vasoativa. Foram introduzidas antibioticoterapia e medidas de suporte. Apresentou melhora hemodinâmica e respiratória progressiva, porém mantinha febre e alteração de provas inflamatórias. Durante internação, evoluiu com conjuntivite não purulenta bilateral, descamação de mão e pés, língua em framboesa e linfonodomegalia cervical, recebendo diagnóstico de doença de Kawasaki. Recebeu gamaglobulina e, por conta de quadro clínico refratário, foi administrado também corticoide, evoluindo afebril 24 horas após. Não apresentou alterações coronarianas. O único agente isolado foi Influenza B, mesmo realizando painel viral e investigação para COVID-19 com reação em cadeia da polimerase e sorologia. Durante internação, apresentou tromboembolismo pulmonar, e, em investigação de coagulopatias, foi diagnosticada com mutação em heterozigose de fator V de Leiden. Há uma potencial associação entre doença de Kawasaki e infecção por Influenza B ou outros vírus, como o coronavírus e, por isso, esses diagnósticos devem ser investigados nos pacientes pediátricos, incluindo adolescentes, com quadros febris prolongados.

ABSTRACT We report a case of Influenza B infection and Kawasaki disease in an adolescent, diagnosed during the COVID-19 pandemic. An asthmatic female adolescent presented with fever and flu-like symptoms for 7 days and was admitted with acute respiratory failure requiring mechanical ventilation. She progressed with hemodynamic instability responsive to vasoactive drugs. Antibiotic therapy and support measures were introduced, showing progressive hemodynamics and respiratory improvement, however with persistent fever and increased inflammatory markers. During the hospitalization, she developed bilateral non-purulent conjunctivitis, hand and feet desquamation, strawberry tongue, and cervical adenopathy, and was diagnosed with Kawasaki disease. She was prescribed intravenous immunoglobulin and, due to the refractory clinical conditions, corticosteroid therapy was added; 24 hours later, the patient was afebrile. No coronary changes were found. A full viral panel including COVID-19 C-reactive protein and serology could only isolate the Influenza B virus. During the hospitalization, she was diagnosed with pulmonary thromboembolism; coagulopathies were investigated, and she was diagnosed with heterozygous factor V Leiden mutation. There is a potential association between Kawasaki disease and infection with Influenza B or with other viruses such as coronavirus. Therefore, this association should be considered in pediatric patients, adolescents included, with prolonged febrile conditions.

Molecular characteristics of the hemagglutinin 1 and neuraminidase genes of influenza B viruses isolated in Yancheng city from 2015 to 2017 / 中华疾病控制杂志

Objective To analyze the genetic characteristics of the hemagglutinin （HA) and neuraminidase （NA) genes of influenza B viruses isolated in Yancheng City from 2015 to 2017. Methods The throat swab specimens of influenza-like illness( ILI) from sentinel surveillance hospital and outbreak sites were collected and sent to Yancheng CDC for virus nucleic acids and virus isolation testing. After validation with serological tests, eighteen strains of influenza B virus isolates were selected to amplify their HA1 and NA genes through RT-PCR assay. Their molecular characteristics of the obtained viral HA1 and NA gene sequences were analyzed using bioinformation software from three aspects, including nucleic acid level, amino acid level and molecular evolution level. Results Basically, the clustering relationships and the branche patterns between HA1 and NA genes from the 18 Yancheng influenza B virus strains were similar. The Yamagata lineage strains in 2015 were distributed in the Yamagata Clade 3 branch, belonging to Phuket/3073 strains. The Victoria lineage strains in 2016-2017 were distributed in the Victoria Clade 1A branch, belonging to Brisbane/60 strains. D196N substitution was detected on HA1 protein in all of Yamagata lineage strains at 190-helix epitope; Amino acid substitutions of victoria lineage strains involved two antigenic epitopes, 117 and 129 sites of 120-loop epitope and 197 and 199 sites of 190-helix epitope. No Intra-lineage or inter-lineage rearrangements occurred in Yancheng strains. Eighteen influenza B strains had no mutations in catalytic residues and drug resistant sites of NA genes. Conclusion The Yamagata strains well matched with vaccine strain B/Phuket/3073/2013. The HA1 and NA genes of victoria lineage strains circulated in Yancheng City during 2016 to 2017 are changing gradually. The accumulation of these mutations will result in antigenic drift of victoria lineage strains and increase the mismatch of the IFV field stains with the available vaccine strains, which may reduce the protective effect of flu vaccine.

Establishment of RIG-I knockout 293T cell line and its effect on the replication of influenza B virus / 生物工程学报

The CRISPR/Cas9 gene editing technology directs Cas9 protein to recognize, bind and cleave the target site specifically by using artificial single-guide RNA (sgRNA), through non-homologous end joining or homologous end-recombinant repair mechanisms of cells, which can be engineered to knockout or knock-in of genomes. RIG-I is a pattern recognition receptor that recognizes the 5'-triphosphate-containing RNA in the cytoplasm and activates IRF3/7 and NF-κB by interacting with the downstream signaling molecule MAVS, thus initiating the expression of type I interferons and inflammatory factors. Previous studies found that influenza B virus (IBV) can up-regulate the expression of RIG-I. In the present study, to explore whether RIG-I is the major receptor for IBV to active the antiviral innate immune response and its effect on IBV replication, RIG-I gene in 293T cells was knocked out by CRISPR-Cas9 system, and a stable RIG-I knockout 293T (RIG-I(-/-) 293T) cell line was screened by puromycin pressure. The results of Western blotting showed that RIG-I was not expressed in this cell line after IBV or Sendai virus (SeV) infection, indicating that the RIG-I(-/-) 293T cell line was successfully constructed. The transcription levels of interferons, inflammatory factors and interferon-stimulated genes in RIG-I(-/-) 293T cells which were infected by IBV decreased significantly compared with those in wild-type 293T cells. Moreover, the phosphorylation of p65 and IRF3 were not detected in IBV or SeV infected RIG-I(-/-) 293T cells. It is indicated that the expression of cytokines mainly depends on the RIG-I-mediated signaling pathway at the early stage of IBV infection. Furthermore, the multi-step growth curves of IBV in the wild type and RIG-I(-/-) 293T cells showed that RIG-I inhibited the replication of IBV. Collectively, the RIG-I knockout 293T cell line was successfully constructed. We found that RIG-I is the main receptor for IBV to active the antiviral innate immune response and is critical for inhibiting IBV replication, which lays the foundation for further study of IBV infection mechanism.

Miocarditis fulminante en adultos por el virus de la influenza B: reporte de dos casos y revisión de la literatura / Fulminant myocarditis due to the influenza B virus in adults: Report of two cases and literature review

Resumen La miocarditis es una enfermedad inflamatoria del miocardio. Las infecciones virales son la causa más común, aunque también puede deberse a reacciones de hipersensibilidad y de etiología autoinmunitaria, entre otras. El espectro clínico de la enfermedad es variado y comprende desde un curso asintomático, seguido de dolor torácico, arritmias y falla cardiaca aguda, hasta un cuadro fulminante. El término 'fulminante' se refiere al desarrollo de un shock cardiogénico con necesidad de soporte vasopresor e inotrópico o dispositivos de asistencia circulatoria, ya sea oxigenación por membrana extracorpórea o balón de contrapulsación intraaórtico. Cerca del 10 % de los casos de falla cardiaca por miocarditis corresponde a miocarditis fulminante. La miocarditis por influenza se considera una condición infrecuente; no obstante, su incidencia ha aumentado desde el 2009 a raíz de la pandemia de influenza por el virus AH1N1. Por su parte, la miocarditis por influenza de tipo B sigue siendo una condición infrecuente. Se describen aquí dos casos confirmados de miocarditis fulminante por el virus de la influenza B atendidos en un centro cardiovascular, que requirieron dispositivos de asistencia circulatoria mecánica.

Abstract Myocarditis is an inflammatory disease of the myocardium. Viral infections are the most common cause, although it can also be due to hypersensitivity reactions and autoimmune etiology, among other causes. The clinical spectrum of the disease is varied, from an asymptomatic course, followed by chest pain, arrhythmias, and acute heart failure, to a fulminant episode. The term fulminant refers to the development of cardiogenic shock with a need for vasopressor support and inotropic or assisted circulation devices either extracorporeal membrane oxygenation (ECMO) or intra-aortic counterpulsation balloon. About 10% of cases of heart failure due to myocarditis correspond to fulminant myocarditis. Influenza myocarditis has been considered an infrequent condition. However, its incidence has increased since 2009 as a result of the AH1N1 pandemic; otherwise, myocarditis due to the Influenza type B virus remains an infrequent entity. We describe the experience in a cardiovascular center of two confirmed cases of fulminant myocarditis due to influenza B that required circulatory assistance devices.

Construction of influenza B virus vero cell adapted strain by genetic reassortment / 中华实验和临床病毒学杂志

Objective@#To construct influenza B virus Vero cell adapted strain by genetic recombination technology by using the influenza B virus Vero cell adapted strain as the parent strain.@*Methods@#The chick embryo and Vero cell were co-infected with influenza virus Vero cell adapted strain B/Malaysia/2506/2004 Va (Bv) and the vaccine strain B/massachusetts/2/2012 (BX-51B) recommended by WHO. The reassortants were screened with the anti-Bv serum. Plaque-purified reassortants were used to screen for Vero cell-adapted influenza B virus strains containing the surface antigen of the epidemic strain.@*Results@#A Vero cell-adapted influenza B virus strain was obtained with successive passage in Vero cells. The hemagglutination inhibition test and the one-way immunogold agar diffusion test both showed that the reassortant virus was homologous to NYMC BX-51B, and sequence analysis result showed that the reassortment virus has the same HA and NA gene with the vaccine strain.@*Conclusion@#B/Malaysia/2506/2004Va (Bv) can be used as a parent strain to prepare Vero cell vaccine against influenza B virus.

Genetic variations and epidemiological characteristics of influenza B virus in Xinxiang from 2012 to 2019 / 中华疾病控制杂志

Objective To investigate the genetic variation and epidemiological characteristics of influenza B virus in Xinxiang to provide policy basis for local influenza vaccination. Methods The influenza surveillance data in Xinxiang from January 2012 to February 2019 was analyzed. 23 isolated influenza B virus were randomly selected for hemagglutinin (HA) and neuraminidase (NA) gene sequencing. Sequence alignment was conducted by using DNAman software and phylogenetic tree analysis was conducted using Neighbor-Joining method. Results Yamagata (BY) and Victoria (BV) strains of influenza B virus circulated alternately every other year in Xinxiang, mainly among people aged 0-15 years (91.4%). The dominant influenza B lineages from 2015 to 2016 and from 2017 to 2018 did not match the corresponding trivalent vaccine strain of the year. The HA phylogenetic tree revealed that 87.5% (7/8) of BV strains coexisted with the vaccine strain in one branch, while 88.98% (8/9) of BY strains from 2013 to 2015 were not in the same branch as the corresponding vaccine strain, with 5 epitope site mutions N116K, S150L, N165Y, D196N and N202S. No drug-resistant site mutation was identified in the NA gene. A total of 6 intra-lineage reassortants were identified. Conclusions The influenza B lineage in the trivalent vaccine recommended by WHO did not match the dominant circulating B lineage of Xinxiang in some epidemic year. Therefore, quadrivalent vaccines are recommended to use in susceptible population, especially under the age of 15. In addition, there are large variations in HA gene of the epidemic BY strain compared with the corresponding vaccine. Then, a vaccine more sutable for the epidemic strains in China is expected to be developed.

Benign Acute Childhood Myositis Associated with Influenza B Virus / 대한신경근육질환학회지

Influenza B virus infections appear to be more common extra-respiratory tract symptoms, compared to influenza A virus infections. Benign acute childhood myositis (BACM) is a benign disease that is caused mainly by many viruses like influenza A or B virus infection. Usually BACM is fully cured with only supportive treatment without unnecessary investigation or invasive procedure. This report describes an eight-year-old boy with acute bilateral calf pain and walking difficulty who diagnosed with BACM after influenza B virus infection.

Nucleoprotein vaccine induces cross-protective cytotoxic T lymphocytes against both lineages of influenza B virus

PURPOSE: The influenza B virus diverges into two antigenically distinct lineages: B/Yamagata and B/Victoria. Influenza B is the dominant circulating virus during some influenza seasons, and recent data demonstrated that influenza A and B infection similarly cause severe clinical symptoms in hospitalized patients. Nucleoprotein (NP) is a good target for a universal influenza vaccine. This study investigated whether NP epitope variation within two lineages affects the dominant cytotoxic T lymphocyte (CTL) responses induced by vaccination and the resultant protective immunity. MATERIALS AND METHODS: The NP of B/Yamagata/16/1988, the representative strain of the Yamagata lineage, includes a dominant CTL epitope, FSPIRITFL, while B/Shangdong/7/1997 from the Victoria lineage has one amino acid difference in this sequence, FSPIRVTFL. Two recombinant replication-deficient adenovirus (rAd)-vectored vaccines expressing either NP were prepared (rAd/B-NP(I) and rAd/B-NP(V), respectively) and administered to BALB/c mice intranasally. To examine the efficacy of vaccination, antibody responses, CTL responses, and morbidity/mortality after challenge were measured. RESULTS: Both vaccines induce similar antibody and CD8 T-cell responses cross-reacting to both epitopes, and also confer cross-protection against both lineages regardless of amino acid difference. CONCLUSION: The rAd-vectored vaccine expressing the NP could be developed as universal influenza B vaccine which provides broader protection.

Phylogenetic analysis of influenza B viruses in Qingdao from 2011 to 2018 / 中华微生物学和免疫学杂志

Objective To investigate the molecular epidemiological characteristics of hemaggluti-nin (HA) and neuraminidase (NA) of influenza B viruses (IBV) isolated in Qingdao from 2011 to 2018. Methods A total of 12236 samples of influenza-like cases in Qingdao from 2011 to 2018 were collected to extract viral RNAs. All samples were screened for influenza A viruses ( IAV) and IBV by one-step multiplex real-time RT-PCR. Lineages of IBV were identified. One hundred and eighty-two strains of IBV were select-ed to amplify HA and NA genes by RT-PCR and then analyzed by sequencing. Phylogenetic analysis and variation analysis of genes and amino acids were carried out. Results IBV was detected almost every year in Qingdao from 2011 to 2018. The positive rate was only slightly lower than that of IAV ( 4. 99％ vs 6. 21％). B/Victoria linkage had two prominent epidemic years (2011-2012, 2015-2016), while B/Yama-gata linkage had three (2013-2014, 2014-2015, 2017-2018). Most of the infected people were children un-der 10 years old, and the people infected with the two lineages had similar age characteristics. Phylogenetic analysis of HA genes showed clusters in Victoria clades of 1A and 1B and Yamagata clades of 2 and 3. IBV of Yamagata lineage had more amino acid mutation sites than those of Victoria lineage in HA genes with grea-ter genetic diversity. The B/Yamagata strains had 12 amino acid mutations and the B/Victoria strains had seven in four major epitopes. In the receptor binding sites, two amino acid mutations were detected in the B/Yamagata strains and three in the B/Victoria strains. In Qingdao, 26 strains of IBV were intra-lineage reas-sortments, mostly of the B/Victoria lineage, and 23 strains were inter-lineage reassortments, mostly between HA-B/Yamagata and NA-B/Victoria strains. A possible resistant strain to NA inhibitor was found. Conclu-sions The significance of IBV in seasonal influenza should not be neglected. Amino acid substitution, in-sertion/deletion and gene reassortment were the main strategies for the natural evolution of IBV. Influenza surveillance was of great importance and influenza vaccine strains needed to be updated in time.