H7N9 avian influenza A virus in China: a short report on its circulation, drug resistant mutants and novel antiviral drugs

Abstract

Introduction: The first human H7N9 avian influenza virus case was reported in Shanghai in 2013. Shortly thereafter, this virus spread to other regions in China. Molecular analysis indicated that the H7N9 virus is a reassortant virus containing internal genes from the H9N2 virus and previously described mammalian adaption markers, which could allow the virus to adapt efficiently to a mammalian host. Fortunately, there is no evidence of sustained person-to-person spread. Most of the human H7N9 cases have a history of exposure to live poultry markets (LPMs). The circulating H7N9 were low pathogenic viruses, however highly pathogenic H7N9 viruses were recently identified in human cases. Areas covered: In the present article, the circulation of H7N9 in LPMs of China, the five waves of H7N9 infection in humans, recently identified drug resistant mutants and potential antiviral drugs against H7N9 are discussed; this may provide further understanding of the evolution and pandemic potential of the H7N9 influenza viruses. Expert commentary: All the data reveal that the major source of H7N9 viruses is LPMs and the H7N9 virus is still circulating widely in China. It is concerning that the recent emergence of highly pathogenic H7N9 viruses may result in highly transmissible viruses in mammalian species.

The Protective Effects of the A/ZJU01/ PR8/2013 Split H7N9 Avian Influenza Vaccine Against Highly Pathogenic H7N9 in BALB/c Mice

“…Worryingly, it involved more confirmed cases than previous epidemics [18, 19]. The isolation of drug-resistant viruses and emergence of highly pathogenic strains in chickens and humans has become a domestic and international concern [7, 20, 21]. …”

Virus-induced pathogenesis, vaccine development, and diagnosis of novel H7N9 avian influenza A virus in humans: a systemic literature review

“…Both M2 ion channel blockers (adamantanes, amantadine, and rimantadine) and NA inhibitors (oseltamivir, zanamivir, peramivir, and laninamivir) are used clinically as antiviral drugs for influenza infection in humans. [90][91][92] Owing to the S31N mutation in the M2 protein, emerging H7N9 viruses are reported to be resistant to adamantine antiviral drugs, 93 which are therefore not recommended for clinical therapy. Oseltamivir, generally used as treatment for influenza infection, reduces the viral load in the respiratory tract of patients.…”

Establishment of sandwich ELISA for detecting the H7 subtype influenza A virus

“…Since the first human infection with avian H7N9 subtype influenza virus detected in early 2013, this novel virus has resulted in 1567 laboratory confirmed cases as of March 2nd, 2018 with a case‐fatality rate of 40% . Compared with the past four epidemic waves, the number of human cases during the fifth wave in 2016 to 2017 become higher than ever before . Among these waves, geographic expansion may be epidemiologically associated with the distribution of live poultry market, the density of human population or poultry movements .…”

“…the number of human cases during the fifth wave in 2016 to 2017 become higher than ever before. 3,4 Among these waves, geographic expansion may be epidemiologically associated with the distribution of live poultry market, the density of human population or poultry movements. 5 Up to now, no evidence implied that this virus can cause sustainable human-to-human transmission.…”