Impact of H5N8 duck and chicken viral isolates on the immunological profile of vaccinated specific pathogen free chickens

Nowadays, there is a global concern about outbreaks caused by the highly pathogenic avian influenza virus H5N8 clade 2.3.4.4 which caused devastating losses in the poultry industry sector. This clade was subdivided into two waves: clade 2.3.4.4A from 2014 to 2015 and clade 2.3.4.4b from 2016 until now. In this literature we aimed to evaluate the efficacy of recently used inactivated commercial avian influenza vaccines against two new Egyptian highly pathogenic avian influenza virus H5N8 isolates of clade 2.3.4.4b, A/chicken/Egypt/1526v/2020/H5N8 (H5N8-CH) and A/Duck/Egypt/Qalubia321/2021 (H5N8-D). Three-week-old specific pathogen free chickens were vaccinated with eight types of the most recently used inactivated avian influenza vaccines containing homologous and heterologous virus to the circulating H5N8 isolates. All specific pathogen free chicken groups were bled weekly post vaccination for antibody analysis using two H5N8 isolates of chicken and duck origin as antigen in hemagglutination inhibition test. Also, all vaccinated chicken groups were challenged 4 weeks post vaccination against the H5N8 duck isolate with a dose of 109 EID50/0.1 mL per chicken to measure the protection percentage of the commercial vaccines used. The results showed that vaccines with homologous and heterologous virus showed variable degrees of accepted protection percentage ranged from 90percent to 100percent, thus it was concluded that not only the genetic and antigenic match of the vaccine strains with the circulating highly pathogenic avian influenza viruses influences vaccine efficiency; other factors, such as manufacturing procedures, adjuvant, antigen content, vaccine dose and administration factors could affect vaccine efficacy, therefore, further vaccine development studies are needed to improve the percentage of protection and prevention of viral shedding against local highly pathogenic avian influenza H5 viruses in Egypt(AU)

En la actualidad, existe una preocupación mundial por los brotes causados por el virus de la gripe aviar altamente patógena H5N8 clado 2.3.4.4 que causó pérdidas devastadoras en el sector de la industria avícola. Este clado se subdividió en dos oleadas: clado 2.3.4.4A de 2014 a 2015 y clado 2.3.4.4b de 2016 hasta ahora. En el presente trabajo, dos aislamientos egipcios de la gripe aviar altamente patógena H5N8 del clado 2.3.4.4b, A/chicken/Egypt/1526v/2020/H5N8 (H5N8_CH) y A/Duck/Egypt/Qalubia321/2021 (H5N8_D), se utilizaron para evaluar la eficacia de vacunas comerciales inactivadas contra la gripe aviar de reciente utilización. Pollos libres de patógenos específicos de tres semanas de edad fueron vacunados con ocho vacunas inactivadas contra la influenza aviar, de uso reciente, que contenían virus homólogos y heterólogos a los aislamientos circulantes de H5N8. Todos los grupos de pollos libres de patógenos específicos fueron sangrados semanalmente tras la vacunación para el análisis de anticuerpos; dos virus H5N8 aislados de pollo y pato se utilizaron como antígeno en la prueba de inhibición de la hemaglutinación. Además, todos los grupos de pollos vacunados fueron retados 4 semanas después de la vacunación con el virus H5N8 aislado de pato, con una dosis de 109 EID50/0,1 mL por pollo, para medir el porcentaje de protección de las vacunas comerciales utilizadas. Los resultados mostraron que las vacunas con virus homólogos y heterólogos presentaron grados variables de aceptada protección, la que osciló entre el 90 por ciento y el 100 por ciento, por lo que se concluyó que no sólo la coincidencia genética y antigénica de las cepas vacunales con los virus circulantes de la influenza aviar altamente patógena influye en la eficacia de la vacuna; otros factores, como los procedimientos de fabricación, el adyuvante, el contenido en antígenos, la dosis de la vacuna y los factores de administración podrían afectar a la eficacia de la vacuna, por lo que es necesario seguir estudiando el desarrollo de vacunas para mejorar la protección y la prevención de la excreción viral contra los virus H5 de la influenza aviar altamente patógena locales en Egipto(AU)

Identification and phylogenetic analysis of five highly pathogenic avian influenza (H5N8) viruses isolated in Urumqi in 2016 / 中华微生物学和免疫学杂志

Objective:To analyze the genetic evolution and molecular characteristics of H5N8 avian influenza viruses (AIVs) isolated from the poultry in a live poultry market (LPM) in Urumqi, Xinjiang.Methods:Oropharyngeal and cloacal swabs of poultry were collected from a LPM in Urumqi in 2016. AIVs were isolated by inoculating swab samples into chicken embryos. Hemagglutination test and RT-PCR were used to identify the AIVs. The genes of isolated AIVs were amplified with the universal primers of AIV and whole-genome sequencing was also performed. Pairwise sequence alignment and analysis of phylogenetic and molecular characteristics were performed using BLAST, Clustal W, MEGA-X and DNAStar software.Results:Five H5N8 AIVs were isolated from poultry. These strains shared a nucleotide identity of 99.70%-100.00%, which indicated that they were from the same source, and were named XJ-H5N8/2016. Phylogenetic analysis based on hemagglutinin( HA), NS and PB2 genes showed that these isolates were clustered together with H5N8 AIVs isolated from the migratory swans in Hubei, Shanxi and Sanmenxia, and the ducks in India during 2016 to 2017. Moreover, they were also clustered together with H5N6 AIVs isolated from minks in China and the first case of human infection in Fujian. The phylogenetic tree of neuraminidase( NA) gene indicated the five isolates clustered together with H5N8 AIVs isolated from ducks in India in 2016, and the phylogenetic trees of PB1, MP, PA and NP genes showed that they were clustered together with H5N8 AIVs isolated from wild birds and poultry in Egypt, Cameroon, Uganda, Congo and other African countries in 2017. The HA cleavage sites of XJ-H5N8/2016 contained five consecutive basic amino acids, indicating high pathogenicity. Multiple mutations in the genes of XJ-H5N8/2016 could enhance its virulence and pathogenicity to mammals. Conclusions:The five strains of H5N8 AIVs isolated from the LPM were highly pathogenic and closely related to the H5N8 AIVs isolated from migratory birds and poultry in Hubei, Shanxi, Sanmenxia area, Africa and India during 2016 to 2017. Meanwhile, some of the viral genes were also closely related to the H5N6 AIVs isolated from the minks and human in China. Multiple mutations could increase the virulence and pathogenicity of AIVs to mammals, which could pose a potential threat to public health.

Novel reassortants of clade 2.3.4.4 H5N6 highly pathogenic avian influenza viruses possessing genetic heterogeneity in South Korea in late 2017

Novel H5N6 highly pathogenic avian influenza viruses (HPAIVs) were isolated from duck farms and migratory bird habitats in South Korea in November to December 2017. Genetic analysis demonstrated that at least two genotypes of H5N6 were generated through reassortment between clade 2.3.4.4 H5N8 HPAIVs and Eurasian low pathogenic avian influenza virus in migratory birds in late 2017, suggesting frequent reassortment of clade 2.3.4.4 H5 HPAIVs and highlighting the need for systematic surveillance in Eurasian breeding grounds.

Recent outbreaks of highly pathogenic avian influenza viruses in South Korea

Outbreaks of H5 highly pathogenic avian influenza viruses (HPAIVs) have caused economic loss for the poultry industry and posed a threat to public health. In South Korea, novel reassortants of HPAIVs such as H5N6 and H5N8 had been circulating in poultry. Here, we will discuss the identity of recent novel reassortants of Korean H5 HPAIVs and the recent advances in vaccine development, which will be useful for controlling HPAIV transmission in poultry and for effectively preventing future epidemics and pandemics.

Phylogeographical characterization of H5N8 viruses isolated from poultry and wild birds during 2014–2016 in South Korea

During 2014–2016 HPAI outbreak in South Korea, H5N8 viruses have been mostly isolated in western areas of the country, which provide wintering habitats for wild birds and have a high density of poultry. Analysis of a total of 101 Korean isolates revealed that primitive H5N8 viruses (C0 group) have evolved into multiple genetic subgroups appearing from various epidemiological sources, namely, the viruses circulating in poultry farms (C1 and C5) and those reintroduced by migratory birds in late 2014 (C2 and C4). No C3 groups were detected. The results may explain the possible reasons of the recent long-term persistence of H5N8 viruses in South Korea, and help to develop the effective measures in controlling HPAI viruses.

Experimental infection of dogs with highly pathogenic avian influenza virus (H5N8)

During the highly pathogenic avian influenza (HPAI) H5N8 virus outbreak in Korea, a dog in layer farm contaminated by H5N8 was reported seropositive for HPAI H5N8. To investigate the possibility of adaptation and transmission of HPAI H5N8 to dogs, we experimentally inoculated dogs with H5N8. Viral genes were weakly detected in nasal swabs and seroconversions in inoculated and contact dogs. Although the H5N8 virus did not induced severe clinical signs to dogs, the results suggest that surveillance of farm dogs should continue as a species in which the avian influenza virus may acquire infectivity to mammals through frequent contact with the virus.

Molecular characterization of highly pathogenic avian influenza H5N8 viruses isolated from Baikal teals found dead during a 2014 outbreak in Korea

Nineteen highly pathogenic avian influenza (HPAI) H5N8 viruses were isolated from wild birds in the Donglim reservoir in Gochang, Jeonbuk province, Korea, which was first reported to be an outbreak site on January 17, 2014. Most genes from the nineteen viruses shared high nucleotide sequence identities (i.e., 99.7% to 100%). Phylogenetic analysis showed that these viruses were reassortants of the HPAI H5 subtype and the H4N2 strain and that their hemagglutinin clade was 2.3.4.4, which originated from Eastern China. The hemagglutinin protein contained Q222 and G224 at the receptor-binding site. Although the neuraminidase protein contained I314V and the matrix 2 protein contained an S31N substitution, other mutations resulting in oseltamivir and amantadine resistance were not detected. No substitutions associated with increased virulence and enhanced transmission in mammals were detected in the polymerase basic protein 2 (627E and 701D). Non-structural-1 was 237 amino acids long and had an ESEV motif with additional RGNKMAD amino acids in the C terminal region. These viruses caused deaths in the Baikal teal, which was unusual, and outbreaks occurred at the same time in both poultry and wild birds. These data are helpful for epidemiological understanding of HPAI and the design of prevention strategies.

Pathogenicity of H5N8 virus in chickens from Korea in 2014

In 2014, two genetically distinct H5N8 highly pathogenic avian influenza (HPAI) viruses were isolated from poultry and wild birds in Korea. The intravenous pathogenicity indices for the two representative viruses were both 3.0. Mortality of chickens intranasally inoculated with the two H5N8 viruses was 100% with a mean death times of 2.5 and 4.5 days. Mortality rates of the contact groups for the two H5N8 viruses were 33.3% and 66.6%. Our study showed that transmissibility of the novel H5N8 viruses was different from that of previously identified H5N1 HPAI viruses, possibly due to genetic changes.