ObjectiveTo analyze the genomic characteristics of H7N9 avian influenza virus in external environment in Huainan city in 2016.
MethodsSamples such as poultry feces, cages, table or cutting board, depilator, poultry drinking water and sewage in live poultry markets were collected. PCR positive samples of H7N9 and H9 subtypes (Ct value ≤30) were selected. RNA was extracted from chicken embryos after isolation and culture.
ResultsFourty-six H7N9 subtypes, 71 H9 subtypes and 38 H5 subtypes were detected from 150 environmental samples in Huainan city in 2016. Two H7N9 subtypes were successfully isolated. Genetic evolution analysis showed that the hemagglutinin (HA) and neuraminidase (NA) genes of the two H7N9 strains in Huainan city were in the branch of the Yangtze river delta, while the other six endogenous genes had no obvious regional distribution and clustering. G186V and Q226L of HA receptor site amino acids mutated. NA stem area missed "QISNT" sequence, while R294K and E119V resistance sites showed no variation. PA gene I550L, PB1 gene I368V and PB2 gene I504V were mutated in the polymerase. The N205S and P42S of the NS-1 gene changed to enhance the pathogenicity. M1 gene N30D, T215A, M2 gene S31N drug resistance gene loci mutated.
ConclusionsThe avian influenza virus was highly prevalent in the live poultry market in Huainan city in 2016. Meanwhile, the ability of the H7N9 subtypes to infect humans has increased. M2 ion channel inhibitor (related to the M2 gene) developed resistance, while NA inhibitors (related to the NA gene) remain susceptible and effective drugs.