Encefalopatía necrotizante aguda asociada a influenza A / Influenza A-associated acute necrotizing encephalopathy

INTRODUCCIÓN: La encefalopatía necrotizante aguda (ENA) es una patología rara, caracterizada por compromiso de conciencia y presencia de múltiples lesiones encefálicas simétricas localizadas principalmente en tá lamo. Se asocia a alta letalidad e importantes secuelas. OBJETIVO: Describir el caso de un paciente escolar con ENA asociada a influenza-A con evolución favorable. CASO CLÍNICO: Paciente de 6 años de edad, con historia de 3 días de evolución de síntomas respiratorios altos asociados a fiebre (39 °C). Veinticuatro horas previo a la consulta destacaba compromiso de conciencia cualicuantitativo. Se realizó punción lumbar con proteinorraquia leve. En resonancia magnética (RM) se identificó focos de restricción a la difusión bilaterales de distribución simétrica, talámicos, en cuerpos mamila res, periacueductales, de tegmento pontino, hipocampales y en ambas cápsulas externas, asociado a componente hemorrágico y edema vasogénico, sugerente de ENA. Recibió tratamiento empírico con metilprednisolona y oseltamivir. Posteriormente, se recibió resultado positivo para virus influenza- AH1. Dado diagnóstico, se decidió administrar inmunoglobulina, evolucionando lento pero favora blemente. Al alta levemente bradipsíquico, con disminución de agudeza visual, lenguaje espontáneo y marcha con apoyo. A los 6 meses de seguimiento presentaba lenguaje y marcha normales, persis tiendo alteración visual a derecha. CONCLUSIÓN: Nuestro paciente presentó una ENA cuyo diagnóstico y manejo oportunos se asociaron a una favorable evolución neurológica en el largo plazo. Si bien la ENA es una patología infrecuente, la morbimortalidad asociada es altísima, por lo que resulta de gran importancia tener un alto grado de sospecha, a fin de solicitar estudio imagenológico dirigido, buscar causas infecciosas relacionadas e iniciar un manejo oportuno.

INTRODUCTION: Acute necrotizing encephalopathy of childhood (ANEC) is a rare disease characterized by alteration of consciousness and multiple symmetric brain lesions mainly involving the thalamus. It presents a high mortality rate and severe sequelae. OBJECTIVE: To describe a school-age patient with influenza A-related ANEC with favorable evolution. CLINICAL CASE: Six-year-old boy with 3 days history of upper respiratory symptoms and fever (39 °C). One day previous to admission, he presented altered state of consciousness. A lumbar puncture was performed, showing a mild increase of protein level in CSF. MRI showed bilateral foci of symmetric restricted signal in the thalamus, mammillary bodies, periaqueductal gray, ventral tegmentum, hippocampus, and in both external capsules, which was compatible with ANEC. The patient received empirical treatment with methylprednisolone and oseltamivir. Subsequently, a positive result was received for influenza. Considering diagnosis and severity of illness, it was decided to administer immunoglobulin. The patient got better slowly but favorably. At discharge, he still was mildly bradypsychic with decreased visual acuity, spontaneous speech and walking with assistance. At 6 months of follow-up, the patient presented normal speech and gait, with persistent visual impairment in the right eye. CONCLUSIONS: Our patient presented ANEC, whose timely diagnosis and management were associated with a favorable neurological evolution in the long term. Although ANEC is an infrequent pathology, it has very high morbidity and mortality rates, so it is very important to have a high degree of suspicion in order to request a targeted imaging study, search for related infectious causes, and start proper treatment.

SARS-CoV-2 and influenza: a comparative overview and treatment implications / SARS-CoV-2 e influenza: revisión comparativa e implicaciones del tratamiento

Abstract Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and Alphainfluenzavirus are RNA viruses that cause coronavirus disease-19 and influenza, respectively. Both viruses infect the respiratory tract, show similar symptoms, and use surface proteins to infect the host. Influenza requires hemagglutinin and neuraminidase to infect, whereas SARS-CoV-2 uses protein S. Both viruses depend on a viral RNA polymerase to express their proteins, but only SARS-CoV-2 has a proofreading mechanism, which results in a low mutation rate compared to influenza. E1KC4 and camostat mesylate are potential inhibitors of SARS-CoV-2 S protein, achieving an effect similar to oseltamivir. Due to the SARS-CoV-2 low mutation rate, nucleoside analogs have been developed (such as EIDD-2801), which insert lethal mutations in the viral RNA. Furthermore, the SARS-CoV-2 low mutation rate suggests that a vaccine, as well as the immunity developed in recovered patients, could provide long-lasting protection compared to vaccines against influenza, which are rendered obsolete as the virus mutates.

Resumen La enfermedad por coronavirus de 2019 y la influenza son causadas por virus ARN: coronavirus tipo 2 del síndrome respiratorio agudo grave (SARS-CoV-2) y Alphainfluenzavirus, respectivamente. Ambos virus infectan el tracto respiratorio, presentan síntomas similares y emplean proteínas de superficie para infectar al huésped. El virus de la influenza requiere de hemaglutinina y neuraminidasa para infectar, mientras que el SARS-CoV-2 utiliza la proteína S. Ambos virus dependen de la ARN polimerasa viral para expresar sus proteínas, pero solo el SARS-CoV-2 cuenta con un mecanismo de corrección de errores, por lo que presenta una baja tasa de mutaciones en comparación con el virus de la influenza. E1KC4 y el mesilato de camostat son inhibidores potenciales de la proteína S del SARS-CoV-2, obteniendo un efecto similar al de oseltamivir. Aprovechando la baja tasa de mutación del SARS-CoV-2, se han desarrollado análogos de nucleósidos (como el fármaco EIDD-2801) que insertan mutaciones letales en el ARN viral. Además, la baja tasa de mutación del SARS-CoV-2, obteniendo un efecto similar al de oseltamivir sugiere que las vacunas desarrolladas, así como la inmunidad generada en pacientes recuperados, podrían brindar protección prolongada, en comparación con las vacunas desarrolladas contra la influenza, que resultan obsoletas frente a una cepa mutada.

The influenza season 2016/17 in Bucharest, Romania - surveillance data and clinical characteristics of patients with influenza-like illness admitted to a tertiary infectious diseases hospital

ABSTRACT Background: Influenza continues to drive seasonal morbidity, particularly in settings with low vaccine coverage. Objectives: To describe the influenza cases and viral circulation among hospitalized patients. Methods: A prospective study based on active surveillance of inpatients with influenza-like illness from a tertiary hospital in Bucharest, Romania, in the season 2016/17. Results: A total of 446 patients were tested, with a balanced gender distribution. Overall, 192 (43%) patients tested positive for influenza, with the highest positivity rate in the age groups 3-13 years and >65 years. Peak activity occurred between weeks 1 and 16/2017, with biphasic distribution: A viruses were replaced by B viruses from week 9/2017; B viruses predominated (66.1%). Among the 133 (69.3%) subtyped samples, all influenza A were subtype H3 (n = 57) and all influenza B were B/Victoria (n = 76). Patients who tested positive for influenza presented fewer comorbidities (p = 0.012), except for the elderly, in whom influenza was more common in patients with comorbidities (p = 0.050). Disease evolution was generally favorable under antiviral treatment. The length of hospital stay was slightly longer in patients with influenza-like illness who tested patients negative for influenza (p = 0.031). Conclusions: Distinctive co-circulation of A/H3 and B/Victoria in Bucharest, Romania in the 2016/17 influenza season was found. While the A/H3 subtype was predominant throughout Europe that season, B/Victoria appears to have circulated specifically in Romania and the Eastern European region, predominantly affecting preschoolers and school children.

Monitoramento de vírus respiratórios na região metropolitana de Belo Horizonte, 2011 a 2013 / Monitoreo de vírus respiratórios en la región metropolitana de Belo Horizonte, 2011-2013 / Monitoring respiratory virus infection in the metropolitan area of Belo Horizonte, Brazil, 2011-2013

OBJETIVO: analisar a circulação dos vírus respiratórios em residentes na região metropolitana de Belo Horizonte, Brasil, hospitalizados em Belo Horizonte, de 2011 a 2013. MÉTODOS: estudo descritivo de 5.158 indivíduos com síndrome respiratória aguda grave; foram comparadas as características dos casos confirmados com casos descartados ou sem coleta de swab. RESULTADOS: metade dos vírus isolados foi da influenza A, especialmente os subtipos A(H1N1)pdm09 em pessoas de 20-59 anos e A(H3N2) naquelas com 60 anos ou mais; crianças menores de cinco anos tiveram identificado, com maior frequência, o vírus sincicial respiratório (65,6%), seguido pelo vírus da influenza A (21,2%); o vírus da influenza circulou em todas as estações do ano, e seus períodos de maior incidência intercalaram-se com os de maior atividade do vírus sincicial respiratório. CONCLUSÃO: o monitoramento dos vírus respiratórios contribui para o conhecimento dos períodos de circulação viral e a adoção de medidas de controle específicas.

OBJETIVOS: analizar la circulación de virus respiratorios en residentes de la región metropolitana de Belo Horizonte, Brasil, hospitalizados entre 2011 y 2013. MÉTODOS: estudio descriptivo de 5.158 individuos con infección respiratoria aguda grave; fueron comparadas las características de los casos confirmados con los descartados o sin colecta de swab. RESULTADOS: la mitad de los virus aislados fueron influenza A, especialmente subtipos A(H1N1)pdm09 en personas entre 20-59 años, y A(H3N2) en personas de 60 años o más; los niños menores de cinco años presentaron, con mayor frecuencia, el virus sincicial respiratorio (65,6%), seguido por influenza tipo A (21,2%); el virus de la Influenza circuló en todas las estaciones y los periodos de mayor incidencia se intercalaron con los de mayor actividad del virus sincicial. CONCLUSIÓN: el monitoriamente del virus respiratorio contribuyo para el conocimiento de los periodos de circulación viral y la adopción de medidas de control específicas.

OBJECTIVE: to analyze the circulation of respiratory viruses in people living in the metropolitan area of Belo Horizonte, Brazil, and hospitalized in Belo Horizonte from 2011 to 2013. METHODS: this is a descriptive study of 5,158 patients with Severe Acute Respiratory Syndrome; a comparison was made between the characteristics of confirmed cases and those of discarded cases or cases without swab samples. RESULTS: Influenza A virus accounted for half the isolated viruses, especially subtype A(H1N1)pdm09 among patients aged 20-59 years old, and subtype A(H3N2) in those aged 60 or over; the most frequently identified respiratory virus among children under five years old was respiratory syncytial virus (65.6%), followed by influenza A virus (21.2%); influenza virus circulated in all seasons of the year and its periods of greatest incidence were interspersed with those of higher Respiratory Syncytial Virus activity. CONCLUSION: monitoring respiratory viruses contributes to knowledge about periods of virus circulation and the adoption of specific control measures.

Seasonal Influenza in 2016 in the Eastern Mediterranean Region

In the Eastern Mediterranean Region of WHO, seasonal influenza peaked at the end of 2015 and beginning of 2016 and returned to low levels by mid May 2016. In most of the countries, the timing of the season generally corresponded to patterns seen in the previous years

Influenza infection and Kawasaki disease

INTRODUCTION: The objective of this study was to investigate the possible link between influenza (Flu) infection and Kawasaki disease (KD). METHODS: We examined the medical records of 1,053 KD cases and 4,669 influenza infection cases hospitalized at our institute from January 1, 2011 to December 31, 2013. Cases of KD with concomitant influenza infection formed the KD + Flu group. Each KD + Flu case was matched with 2 KD cases and 2 influenza infection cases, and these cases were assigned to the KD group and Flu group, respectively. The differences in the principal clinical manifestations, course of disease, incomplete KD rate, intravenous immunoglobulin (IVIG) resistance rate, and echocardiographic detection results between the KD + Flu group and KD group were compared. The fever durations and laboratory test results of these three groups were compared. RESULTS: 1) The seasonal variations of the KD + Flu group, KD group and Flu group were similar. 2) The morbidity rate of incomplete KD was higher in the KD + Flu group compared with the KD group. 3) Patients in the KD + Flu group exhibited a longer time to KD diagnosis compared with patients in the KD group. 4) The KD + Flu group exhibited the longest fever duration among the three groups. 5) The CRP and ESR values in the KD + Flu group were higher those in the Flu or KD groups. CONCLUSIONS: Concomitant influenza infection affects the clinical manifestations of KD and can impact the laboratory test results and the diagnosis and treatment of the disease. However, it remains unclear whether influenza contributes to KD etiology. .

Detection of respiratory viruses by real-time polymerase chain reaction in outpatients with acute respiratory infection

Viruses are the major contributors to the morbidity and mortality of upper and lower acute respiratory infections (ARIs) for all age groups. The aim of this study was to determine the frequencies for a large range of respiratory viruses using a sensitive molecular detection technique in specimens from outpatients of all ages with ARIs. Nasopharyngeal aspirates were obtained from 162 individuals between August 2007-August 2009. Twenty-three pathogenic respiratory agents, 18 respiratory viruses and five bacteria were investigated using multiplex real-time reverse transcriptase polymerase chain reaction (RT-PCR) and indirect immunofluorescence assay (IIF). Through IIF, 33 (20.4%) specimens with respiratory virus were recognised, with influenza virus representing over half of the positive samples. Through a multiplex real-time RT-PCR assay, 88 (54.3%) positive samples were detected; the most prevalent respiratory viral pathogens were influenza, human rhinovirus and respiratory syncytial virus (RSV). Six cases of viral co-detection were observed, mainly involving RSV. The use of multiplex real-time RT-PCR increased the viral detection by 33.9% and revealed a larger number of respiratory viruses implicated in ARI cases, including the most recently described respiratory viruses [human bocavirus, human metapneumovirus, influenza A (H1N1) pdm09 virus, human coronavirus (HCoV) NL63 and HCoV HKU1].

Epidemiological survey on pandemic influenza A [H1N1] virus infection in Kurdistan province, Islamic Republic of Iran, 2009

This study evaluated the epidemiology of suspected cases of pandemic influenza A [HINI] virus infection in 2009-2010 in Kurdistan province, a frontier province of the Islamic Republic of Iran. A questionnaire covering demographic characteristics, clinical presentation and outcome, and history of exposure and travel was completed by patients attending health centres and hospitals in the province. Nasal and throat swabs were analysed by RT-PCR. A total of 1059 suspected cases were assessed; HI Nl influenza A was confirmed in 157 [14.8%]. The highest proportion of confirmed cases was 30,0%, among children aged <1 year. In multivariate analysis, previous contact with symptomatic influenza patients [OR - 2.17] and hospitalization [OR = 3.88] were the only significant risk factors for confirmed HINI infection. Age, sex, residency, presenting symptoms and history of national or international travel were not significant. Influenza A [HI Nl] virus has spread in Islamic Republic of Iran; probably transmitted by travellers to Kurdistan

Comparison of the direct fluorescence assay and real-time polymerase chain reaction for the detection of influenza virus A and B in immunocompromised patients

OBJECTIVE: This study evaluated the diagnostic performance of two methods for the detection of influenza virus in immunocompromised transplant patients. METHODS: A total of 475 respiratory samples, 236 from patients in a hematopoietic stem cell transplantation program and 239 from kidney transplant patients, were analyzed by a direct fluorescence assay and the Centers for Disease Control real-time polymerase chain reaction protocol for influenza A and B detection. RESULTS: Influenza detection using either method was 7.6% in the hematopoietic stem cell transplant group and 30.5% in the kidney transplant patient group. Influenza detection by real-time polymerase chain reaction yielded a higher positive rate compared with fluorescence than that reported by other studies, and this difference was more pronounced for influenza A. The fluorescence assay sensitivity, specificity, positive and negative predictive values, and kappa coefficient were 17.6%, 100%, 1, 0.83, and 0.256, respectively, and lower detection rates occurred in the kidney transplant patients. CONCLUSIONS: The real-time polymerase chain reaction performance and the associated turnaround time for a large number of samples support the choice of this method for use in different routine diagnostic settings and influenza surveillance in high-risk patients. .

Influenza A virus infection of healthy piglets in an abattoir in Brazil: animal-human interface and risk for interspecies transmission

Asymptomatic influenza virus infections in pigs are frequent and the lack of measures for controlling viral spread facilitates the circulation of different virus strains between pigs. The goal of this study was to demonstrate the circulation of influenza A virus strains among asymptomatic piglets in an abattoir in Brazil and discuss the potential public health impacts. Tracheal samples (n = 330) were collected from asymptomatic animals by a veterinarian that also performed visual lung tissue examinations. No slaughtered animals presented with any noticeable macroscopic signs of influenza infection following examination of lung tissues. Samples were then analysed by reverse transcription-polymerase chain reaction that resulted in the identification of 30 (9%) influenza A positive samples. The presence of asymptomatic pig infections suggested that these animals could facilitate virus dissemination and act as a source of infection for the herd, thereby enabling the emergence of influenza outbreaks associated with significant economic losses. Furthermore, the continuous exposure of the farm and abattoir workers to the virus increases the risk for interspecies transmission. Monitoring measures of swine influenza virus infections and vaccination and monitoring of employees for influenza infection should also be considered. In addition regulatory agencies should consider the public health ramifications regarding the potential zoonotic viral transmission between humans and pigs.

Prevalence of influenza virus among the paediatric population in Mumbai during 2007-2009.

Purpose: Influenza has a major impact on public heath, annually affecting 15-20% of the global population. Information on the activity of influenza virus in Mumbai is limited. The present study was carried out to determine the prevalence of influenza viruses causing acute respiratory infections in children by molecular methods. Objective: To study the prevalence of influenza viruses among the paediatric population in Mumbai by real-time reverse-transcriptase polymerase chain reaction (rRT-PCR). Materials and Methods: From July 2007 to July 2009, 100 respiratory samples (nasal and throat swabs) were collected from paediatric patients with acute respiratory symptoms. attending out patients department, and admitted to the paediatric wards of B. J. Wadia Hospital for Children, Mumbai. The samples were collected and processed as per World Health Organization (WHO) guidelines. Viral RNA was extracted and one-step rRT-PCR was performed to detect influenza type A (H1 and H3) and influenza type B virus. Results: Out of 100 samples processed by rRT-PCR, a total of 11 samples (11%) were positive for influenza virus. The typing for influenza A subtypes showed 1% (1) positivity for H1 and 5% (5) positivity for H3 subtypes and 5% (5) samples tested positive for influenza type B virus. Conclusion: It was observed that both influenza type A and B viruses were prevalent in Mumbai during the study period. Such surveillance data are important in the early detection of any antigenic variants that may be helpful in global influenza vaccine preparation and for any pandemic preparedness activity.

Desenvolvimento de sistemas de genética reversa para os vírus da doença de gumboro e influenza aviária através do uso de recombinação homóloga em levedura / Development of reverse genetics systems for infectious bursal disease virus and avian influenza by yeast-based homologous recombination

A Doença de Gumboro (DG) é uma doença imunossupressora comum em aves jovens infectadas pelo Vírus da Doença de Gumboro (Infectious Bursal Disease Vírus, IBDV), sendo responsável por perdas econômicas no setor avícola. O vírus influenza apresenta-se com um alto nível de mutação, o que resulta no surgimento de vírus imunologicamente distintos capazes de causar pandemias ou epidemias. Entende-se por sistema de genética reversa viral (SGRV) a geração/recuperação de vírus por meio da transfecção celular do cDNA viral clonado ou seu RNA viral transcrito in vitro. SGRV pode ser usado na elucidação dos mecanismos de replicação do influenza e IBDV, e aplicações biotecnológicas como desenvolvimento de vacinas. Diante desse levantado, objetivou-se a construção de dois SGRVs por recombinação homóloga em levedura (RHL): um para IBDV e outro para influenza aviária (IA). Para o SGRV do IBDV, IBDV foi isolado no Brasil, teve seu genoma amplificado e clonado por RHL no vetor pJG-CMV-HDR. Os clones foram transfectados em fibroblasto de embrião de galinha (FEG) e o vírus gerado (IC-IBDVBr) mostrou estabilidade gênica e fenótipo similar ao vírus parental. A geração e crescimento do IC-IBDVBr não foram possíveis em células Vero. Para o SGRV do IA, IA foi isolado no Brasil, seu genoma foi amplificado e clonado em pDrive/pGEM-T Easy e depois subclonado por RHL no vetor pJGCh2008. Os clones em pJG-Ch2008 responsáveis pela codificação das proteínas do complexo polimerase viral (CPV) foram transfectados simultaneamente em células Human Embryonic Kidney 293T com plasmídeos contendo o gene repórter red fluorescent protein ou Gaussia luciferase, ambos flanqueados pela untransleated region do influenza. A funcionalidade do CPV do IA foi verificada pela expressão de RFP e GLuc. A recuperação do IA em FEG pelos clones em pJG-Ch2008 não foi possível. A funcionalidade do CPV mais a integridade dos clones indicam que a recuperação do IA não foi possível provavelmente devido à eficiência da transfecção celular. A construção do SGRV para IBDV, o primeiro do mundo feito por RHL e o primeiro desenvolvido no Brasil, junto com os passos iniciais para a construção do primeiro SGRV para influenza feito por RHL e a consequente construção do CPV por essa tecnologia, disponibilizam ao país ferramentas capazes de contribuir no esclarecimento do ciclo replicativo de ambos os vírus, além de criar bases para o futuro desenvolvimento de vacinas e vetores virais.

Virological surveillance and antiviral resistance of human influenza virus in Argentina, 2005–2008 / Vigilancia virológica y resistencia a los antivíricos del virus de la gripe humana en la Argentina, 2005–2008

Objective. To describe the virological characteristics of the influenza strains circulating in Argentina in 2005–2008 and to assess the prevalence of antiviral resistance. Methods. On the basis of their geographical spread and prevalence, influenza A and B isolates grown in Madin–Darby canine kidney cells were selected after antigenic and genomic characterization to be analyzed for antiviral resistance by enzymatic assay and pyrosequencing. Amantadine susceptibility was evaluated by pyrosequencing for known resistance markers on 45 strains of influenza A. Susceptibility to oseltamivir and zanamivir was evaluated by enzymatic assay of 67 influenza A and 46 influenza B strains, some of which were further analyzed by sequencing the neuraminidase gene. Results. Resistance to amantadine was observed only on A(H3N2) strains (29/33); all of them carried the mutation S31N in their M2 sequence. Oseltamivir resistance was observed in 12 (34.3%) of the 35 A(H1N1) strains from 2008; all of them carried the mutation H275Y in their neuraminidase sequence. All these viruses remained sensitive to zanamivir. Conclusions. This study describes a high incidence of amantadine-resistant influenza A(H3N2) viruses since 2006 and an unprecedented increase in oseltamivir resistance detected only in influenza A(H1N1) viruses isolated in 2008. Influenza A and B viruses were more sensitive to oseltamivir than to zanamivir, and influenza A viruses were more sensitive to both neuraminidase inhibitors than the influenza B viruses. The national data generated and analyzed in this study may help increase knowledge about influenza antiviral drug resistance, which is a problem of global concern.

Objetivo. Describir las características virológicas de las cepas de virus de la gripe que circulaban en la Argentina entre el 2005 y el 2008, y evaluar la prevalencia de la resistencia a los antivíricos. Métodos. Según su diseminación geográfica y su prevalencia, se seleccionaron aislados de gripe A y B cultivados en células renales caninas de Madin-Darby después de su caracterización antigénica y genómica, y se analizó su resistencia a los antivíricos mediante análisis enzimático y pirosecuenciación. La sensibilidad a la amantadina se evaluó por pirosecuenciación para los marcadores conocidos de resistencia en 45 cepas de gripe A. La sensibilidad al oseltamivir y al zanamivir se evaluó mediante análisis enzimático de 67 cepas de gripe A y 46 cepas de gripe B, algunas de las cuales se analizaron en mayor profundidad mediante la secuenciación del gen de la neuraminidasa. Resultados. Se observó resistencia a la amantadina solo en las cepas de gripe A (H3N2) (29/33); todas ellas tenían la mutación S31N en su secuencia de M2. Se observó resistencia al oseltamivir en 12 (34,3%) de las 35 cepas de gripe A (H1N1) aisladas en el 2008; todas ellas tenían la mutación H275Y en su secuencia de neuraminidasa. Todos estos virus conservaron su sensibilidad al zanamivir. Conclusiones. En este estudio se describe una incidencia elevada del virus de la gripe A (H3N2) resistente a la amantadina desde el 2006 y un aumento sin precedentes de la resistencia al oseltamivir detectada solo en los virus de la gripe A (H1N1) aislados en el 2008. Los virus de la gripe A y B fueron más sensibles al oseltamivir que al zanamivir y los virus de la gripe A fueron más sensibles a ambos inhibidores de la neuraminidasa que los virus de la gripe B. Los datos nacionales generados y analizados en este estudio pueden ayudar a aumentar los conocimientos acerca de la resistencia a los fármacos antivíricos dirigidos contra el virus de la gripe, lo que es un motivo de preocupación mundial.

Prevalencia serológica del virus de influenza A en cerdos en Argentina durante la temporada 2002: evaluación mediante inhibición de la hemaglutinación y ELISA / Seroprevalence of the swine Influenza virus in fattening pigs in Argentina in the 2002 season: evaluation by hemagglutination-inhibition and ELISA tests

Se evaluó la prevalencia serológica del virus de influenza mediante las pruebas de inhibición de la hemaglutinación (IHA) y ELISA para los subtipos H1N1 y H3N2 en 13 granjas porcinas de Argentina. Se compararon los resultados obtenidos mediante ambas pruebas en términos individuales y de establecimientos. La prevalencia individual por la técnica de IHA fue de 38,46% a 100% para H1 y de 7,69% a 100% para H3. Por la técnica de ELISA, la prevalencia individual fue de 2,33% a 6,9% para H1 y de 9,65% a 48% para H3. No se observaron diferencias significativas entre ambas técnicas a escala de granja (H1: p=0,20; H3: p=0,11). La concordancia entre las pruebas fue nula al tomar como unidad de referencia el animal (H1: 0,005; H3: 0,070), mientras que en términos de establecimiento fue escasa (H1: 0,350; H3: 0,235). Considerando la alta prevalencia individual obtenida por la prueba de IHA y la alta sensibilidad de esta técnica, se podría sugerir que en las poblaciones porcinas de la Argentina circularon cepas virales humanas o cepas porcinas con gran proximidad filogenética a las utilizadas en este estudio desde el año 2002.

The seroprevalence of the Influenza virus against H1N1 and H3N2 was determined by the hemagglutination-inhibition test (HI) and a commercial swine influenza ELISA kit, in 13 Argentinean swine herds. The results of within-herd and between-herd prevalence obtained by both tests were statistically correlated. The within-herd prevalence observed by the HI test varied from 38.46 to 100% against H1 and 7.69 to 100% for H3. When the within-herd prevalence was measured with the ELISA test, it varied from 2.33 to 6.9% for H1 and 9.65 to 48% for H3. No statistical differences were observed at herd level between HI and ELISA (H1: p = 0. 20; H3: p=0.11). No agreement between HI and ELISA detected prevalence was observed when the within-herd prevalence was compared (H1: 0.005; H3: 0.070), while the agreement at herd level was considered poor (H1: 0,350; H3: 0,235). The high within-herd prevalence values observed with the HI test and the high sensibility of this test might show that human strains or swine strains phylogenetically closely related to the humans strains used in the HI test in this study have been affecting the swine population since 2002.

Comparative study on three different imported isolates of avian influenza virus

Three imported strains of low pathogenic H5N2 avian influenza [AI] from the United State Department of Agriculture [USDA] of the United States [A/Ty/CA/209092/02, A/Chicken/ PA/13609/93 and A/Ty/MN/3689-1551/81] were used to prepare 3 experimental batches of oil emulsion vaccine against AI designated as [1, 2 and 3] in order. Evaluation of the prepared vaccines was carried out using standardized hemagglutination inhibition test [HI]. Evaluation was based on using the same antigen used for preparation of vaccine as HI antigen [homologous strain]. Cross reactivity test was carried out between the three different strains and the prepared vaccines. Moreover, the H5N1 locally isolated highly pathogenic avian influenza [HPAI] A/Ch/Eg/2009 H5N1 was used as a heterologous antigen for HI test against the prepared vaccines. Obtained results revealed that a protective titer was obtained by vaccine 1 and 2. Using homologous virus as an antigen produce high titer rather than using other viruses, the vaccines failed to produce HI antibodies against locally isolated H5N1 AI virus

Assessment of a rapid immunochromatographic assay for the detection of avian influenza viruses

Rapid spreading of the low pathogenic avian influenza virus [AIV] caused by the H9N2 subtype and the highly pathogenic AIV caused by H5N 1 have caused serious economic losses in the poultry industries of Asia. Therefore, the early detection of AIVs is crucial for the control of the disease. In the present study, the applicability of a rapid immunochromatographic [RIC] assay, which specifically detected type A antigens of AIVs, was evaluated. This assay detected H9N2 viruses at 10[3.2] ELD[50]/ml and H5, H7 and H9 antigens at 128 HA titers, but did not react with other respiratory viruses. The assessment of cloacal swab samples prepared from 1 to 10 d post-inoculation [PI] revealed that the first positive samples were detectable on day 2 and 3 PI, and the last positive samples were detectable on day 10 and 9 PI, by the virus isolation [VI] and RIC assays, respectively. Collectively, the relative specificity, sensitivity, positive predictive value, negative predictive value, accuracy and correlation rate of the RIC and VI assays, were 100%, 71.5%, 100%, 78.5%, 0.86, and 0.98, respectively. There was also a good correlation [K> 0.81] between the results of the haemagglutination [HI], VI and RIC assays of cloacal/tracheal swab samples that were obtained from broiler flocks involved with viral respiratory diseases. Overall, RIC showed a low sensitivity and high specificity for the rapid diagnosis of H9N2 isolates in both experimental and clinical infections

Características del virus influenza y diagnóstico de laboratorio / Laboratory diagnosis and characterization of influenza virus

El virus influenza es causa frecuente de infección respiratoria. Pertenece a la familia Orthomixoviridae, existiendo tres géneros. Todos comparten características estructurales con un manto de lípidos y glicoproteínas hemaglutinina y neuraminidasa, que participan en la patogenicidad viral y determinando los diferentes subtipos de virus; en su interior una hebra de ácido ribonucleico de polaridad negativa. El presente artículo resumen las principales características de laboratorio, clínicas y de diagnóstico de este emergente virus respiratorio.

Surveillance of adamantane resistance among influenza A H3 viruses isolated in Argentina between 2001 and 2007 / Vigilancia de la resistencia a los adamantanos entre los virus influenza A H3 aislados en Argentina entre 2001 y 2007

A dramatic rise in the frequency of resistance to adamantane drugs by influenza A H3 viruses, associated with a single amino acid replacement in the viral matrix M2 protein, has occurred in multiple countries worldwide in recent years. We investigated the frequency of adamantane-resistant influenza A H3 viruses in Argentina during the period 2001- 2007. We used reverse transcription followed by polymerase chain reaction. The obtained products were sequenced for the detection of mutations of the M2 gene relevant to the resistance phenotypes. The HA1 sequences of the sensitive and resistant strains were also analyzed to clarify whether they had any relevance to the resistant mutations. Twenty out of 55 (36%) strains were identified with the resistance-conferring substitution at amino acid 31 (Serine 31 Asparagine). No resistant viruses were detected between 2001 and 2005. All strains isolated in 2006 and four out of five isolates from 2007 were resistant. None of the patients had received previous treatment with amantadine and/or rimantadine. The HA1 analysis showed that there were only two changes (Serine193 Phenylalanine and Aspartic acid 225 Asparagine) present in the strains with the M2 substitution at position 31. Our data indicate that since 2006 there has been a significant increase of adamantane-resistant influenza A H3 viruses, which raises concern over the spread of these viruses in Argentina.

En los últimos años, se ha detectado un aumento de virus influenza A H3 resistentes a los adamantanos en distintos países, asociados mayoritariamente con el reemplazo de un único aminoácido de la proteína matriz M2. Se investigó la frecuencia de virus influenza A H3 resistentes a los adamantanos en Argentina entre 2001 y 2007. Se utilizó la transcripción reversa seguida de la reacción en cadena de la polimerasa y de la técnica de secuencia directa para la detección de mutaciones en el gen que codifica para la proteína M2, relevantes para los fenotipos de resistencia. También se analizó la secuencia de la porción HA1 de cepas resistentes y sensibles, para intentar establecer alguna relación con las mutaciones de M2. De un total de 55 cepas, 20 (36%) fueron resistentes debido a un cambio aminoacídico en la posición 31 (serina 31 asparagina). No se detectaron cepas resistentes entre 2001 y 2005. Las cepas aisladas en el 2006 y 4 de 5 cepas obtenidas en el 2007 fueron resistentes. Ninguno de los pacientes de los que se habían aislado esas cepas había recibido tratamiento antiviral con anterioridad. En la porción secuenciada de HA1 se encontraron dos cambios (serina 193 fenilalanina y ácido aspártico 225 asparagina), presentes sólo en las cepas que tuvieron la mutación en la posición 31 de M2. Desde el año 2006 se ha registrado en Argentina un aumento significativo de la circulación de virus influenza A H3 con genotipo resistente, lo que genera expectativa con respecto a su diseminación en nuestro país.