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Background In recent years, Vietnam has suffered multiple epizootics of influenza in poultry. Methods From 10 January 2019 to 26 April 2021, we employed a One Health influenza surveillance approach at live bird markets (LBMs) and swine farms in Northern Vietnam. When the COVID-19 pandemic permitted, each month, field teams collected oral secretion samples from poultry and pigs, animal facility bioaerosol and fecal samples, and animal worker nasal washes at 4 LBMs and 5 swine farms across 5 sites. Initially samples were screened with molecular assays followed by culture in embryonated eggs (poultry swabs) or Madin-Darby canine kidney cells (human or swine swabs). Results Many of the 3493 samples collected had either molecular or culture evidence for influenza A virus, including 314 (37.5%) of the 837 poultry oropharyngeal swabs, 144 (25.1%) of the 574 bioaerosol samples, 438 (34.9%) of the 1257 poultry fecal swab samples, and 16 (1.9%) of the 828 human nasal washes. Culturing poultry samples yielded 454 influenza A isolates, 83 of which were H5, and 70 (84.3%) of these were highly pathogenic. Additionally, a positive human sample had a H9N2 avian-like PB1 gene. In contrast, the prevalence of influenza A in the swine farms was much lower with only 6 (0.4%) of the 1700 total swine farm samples studied, having molecular evidence for influenza A virus. Conclusions This study suggests that Vietnam's LBMs continue to harbor high prevalences of avian influenza A viruses, including many highly pathogenic H5N6 strains, which will continue to threaten poultry and humans. [ABSTRACT FROM AUTHOR]

Background Newly emergent and virulent strains of H7N9 avian influenza virus are rapidly spreading in China and threaten to invade Vietnam. We sought to introduce aerosol sampling for avian influenza viruses in Vietnam. Methods During October 2017, National Institute for Occupational Safety and Health 2-stage aerosol samplers were assembled on a tripod and run for 4 hours. Concomitantly, up to 20 oropharyngeal (OP) swab samples were collected from chickens and ducks distanced at 0.2–1.5 m from each sampler. Results The 3 weeks of sampling yielded 30 aerosol samples that were 90% positive for influenza A, by quantitative reverse-transcription polymerase chain reaction, and 116 OP swab sample pools (5 samples per pool) that were 47% positive. Egg cultures yielded 1 influenza A virus (not H5 or H7) from aerosol and 25 influenza A viruses from OP swab sample pools (5 were H5 positive). The association between positive sample types (over time and position) was strong, with 91.7% of positive OP pooled swab samples confirmed by positive aerosol samples and 81% of influenza A positive aerosol samples confirmed by positive OP swab samples. Conclusions We posit that aerosol sampling might be used for early warning screening of poultry markets for novel influenza virus detection, such as H7N9. Markets with positive aerosol samples might be followed up with more focused individual bird or cage swabbing, and back-tracing could be performed later to locate specific farms harboring novel virus. Culling birds in such farms could reduce highly pathogenic avian influenza virus spread among poultry and humans. [ABSTRACT FROM AUTHOR]

The article explores the correlation between lung cytokine gene expression and increased severity of disease in a novel H4N8 influenza virus. Topics discussed include the epidemiology and medical risks presented by interspecies transmission of Influenza A virus, the reason for the elevated proinflammatory cytokine expression in 6KS0185 infected mice, and the influence of type I interferons (IFN) on influenza virus replication.

Abstract: H4N8 subtype avian influenza viruses were isolated from shorebirds in eastern Hokkaido. All the isolates shared >99.7% nucleotide homology, and all the viral genes except for PB1 were highly related to those of A/red-necked stint/Australia/1/04. Thus, the isolates were regarded as PB1 reassortants. The most similar PB1 gene was identified in A/mallard/New Zealand/1615-17/04 (H4N6) with nucleotide homology of 90.9%. BALB/c mice intranasally inoculated with the H4N8 isolates developed severe respiratory disease, which eventually led to death in some mice. The virus was isolated from the lungs, and viral antigen was detected in the lungs with pneumonia. Other H4 subtype viruses tested did not cause any symptoms in mice, although these viruses were also isolated from the lungs. The PB2 gene of the H4N8 isolates contains K482R, but not the E627K or D701N substitutions. The PB1-F2 gene of the isolates consists of a 101-amino acid unique sequence, but lacks the N66S mutation. [Copyright &y& Elsevier]

The epidemiological information has obtained on avian influenza virus (AIV) in eastern Hokkaido, Japan, where AIV surveillance has not been performed. Cloacal or fecal samples obtained from migratory water birds were screened for AIV both by real-time reverse transcriptase polymerase chain reaction to detect the influenza A virus matrix (M) gene and by egg inoculation. Between 2007 and 2009, a total of 2,488 samples were collected from various avian species in Abashiri, Kushiro, Nemuro and Tokachi districts of eastern Hokkaido. AIVs were isolated from 18 of those samples (0.7%). No AIV was isolated from the 1,449 samples collected in Abashiri, Kushiro and Nemuro districts, although 6 were positive for the M gene by RRT-PCR. In contrast, 52 (5.0%) of the 1,039 samples collected from ducks in Tokachi district were M gene positive; AIVs were isolated from 18 of those samples (1.7%). The isolates included H3N5 (1 isolate), H3N6 (1), H3N8 (9), H4N2 (1), H4N6 (2), H6N5 (1), H6N8 (1), and H11N3 (2) subtypes. H3N5 and H11N3 subtypes have not been frequently isolated, and our study is the first to report H3N5 and the second to report H11N3 in Japan. Phylogenetic analysis revealed that the M genes of all isolates belonged to the Eurasian lineage.