Novel avian flu subtype H3N6 found co-circulating with H3 and H5 viruses
A novel avian flu subtype, H3N6, was found co-circulating with other viruses on duck farms in China's Hunan province, according to a May 6 study in Scientific Reports.
Researchers analyzed 10 avian flu strains isolated from domestic ducks, geese, and duck pond water from 2014 to 2015 on farms in Hunan's Wugang city. Avian flu viruses H3N2, H3N8, and H5N6 were found co-circulating in domestic ducks, along with a new subtype, H3N6, which likely derived from H5N6. The new virus possesses a neuraminadase deletion that makes it unique compared with other H3 subtypes, the authors said.
All four subtypes replicated efficiently in mammal cells, including Madin-Darby Canine Kidney (MDCK) epithelial cells, though the H3 viruses grew to higher titers compared with H5N6 in the first 12 hours, followed by a drop in viral load 72 hours after infection. The viruses were also found to replicate well in adenocarcinomic human alveolar basal epithelial (A459) cells.
The H3 viruses and H5N9 also demonstrated low pathogenicity in mice. H3N2 and H3N8 caused high viral titers in the lungs and nasal turbinates of infected mice, while H3N6 and H5N6 were able to replicate effectively only in the lungs. None of the four subtypes caused murine disease or death, the authors said.
Given the occurrence of novel subtypes produced by gene reassortment of co-circulating avian flu viruses, the authors recommended improving biosecurity measures on Chinese poultry farms to reduce the possibility of avian flu outbreaks and interspecies transmission.
May 6 Sci Rep study
Researchers say genetic traits may influence human susceptibility to H7N9
Chinese scientists have identified 64 human genetic peculiarities that they think may affect susceptibility to infection with the H7N9 avian flu virus, according to a report yesterday in Scientific Reports.
The authors hypothesized that genetic characteristics may influence both susceptibility to H7N9 infection and the severity of illness, since relatively few of the many people exposed to poultry during H7N9 outbreaks have contracted the infection.
The team took blood samples from 18 confirmed H7N9 patients, 6 of whom had fatal cases. They extracted the DNA and sequenced the portions of it that encode proteins (exons). This led to the identification of 64 single-nucleotide polymorphisms (SNPs) in 21 genes that were more common in the H7N9 patients than in the general population.
"These mutations were found in genes encoding proteins responsible for multiple key host defense mechanisms, including cytokine production, airway epithelium barrier function and pathogen associated molecular pattern signaling pathway," suggesting that the SNPs may affect susceptibility to H7N9, the report says.
Some of the 21 genes have previously been identified as linked to H7N9 susceptibility, the authors said. For example, an earlier study indicated that dysfunction of a gene called IFITM3 is associated with increased cytokine production during H7N9 infection and is correlated with mortality.
The team acknowledged that their sample was small and that the findings need to be confirmed by further studies, which they are working on.
"Further investigations into the function of these genes in host susceptibility may help identify individuals who are at high risk for infection," they concluded. "In addition, translational research into the function of the genes identified in this study may provide new potential therapeutic targets for influenza virus infection."
May 9 Sci Rep article
