Advanced researches on the inhibition of influenza virus by Favipiravir and Baloxavir

Anti-influenza drugs are one of themost critical pathways for control of influenza virus infection.Drugs that have been developed or are developing may function via different mechanisms,and so far,inhibitors of influenza virus polymerase are among the most promising types of drugs.Favipiravir and Baloxavir,also named T-705 and Xofluza respectively,have been approved for influenza treatment in Japan and the United States.Favipiravir effectively and selectively inhibits the RNA-dependent RNA polymerase(RdRp)of RNA viruses while Baloxavir specifically targets the cap-dependent endonuclease PA of influenza viruses.These two drugs have been suggested as the first candidate drugs for influenza infection treatment,especially for strains resistant to other anti-influenza drugs.This review will focus on the pharmaceutical mechanisms and anti-influenza activity of these two drugs.

Research progress in human infection with avian influenza H7N9 virus

Since the identification of the novel reassortant avian influenza A(H7N9) virus in China in 2013, until Jun 30, 2017, the virus has caused five epidemic waves leading to a total of 1,552 human infections, with a fatality rate of about 40%. In the spring of2017, highly pathogenic avian influenza(HPAI) H7N9 virus emerged and has caused 25 human infections. The HPAI H7N9 virus has some biological differences from the LPAI one, such as its multiple basic amino acid residues on HA leading to its independence on trypsin for replication. The pathogenicity of the HPAI H7N9 virus to experimental animals or humans is still unclear. A(H7N9) vaccine development for pandemic preparedness is ongoing, including the reassortment(H7N9/PR8)reverse genetic based vaccine, the virus like particle(VLP) vaccine, the intranasal live attenuated influenza vaccine(LAIV),the non-adjuvant Vero cell culture-derived inactivated whole-virus vaccine, the MDCK culture-derived vaccine, the H7 DNA vaccine and the recombinant replicative H7N9 virus \(H7N9-53 TM\) vaccine. Five neuramidinase resistant sites of A(H7N9)virus isolated from patients have been reported. Some alternative drugs have been studied, such as DAS181(Fludase), ribavirin,troglitazone and minocycline. Persistent surveillance and enhanced global control are essential to fight against human infections with A(H7N9) virus.

Different Starting Dominant Strain of Seasonal Influenza in China and Other Neighboring Asian Countries in 2019−2020 Winter Season

Introduction:Seasonal influenza is a prevalent and highly contagious acute respiratory disease that causes a major global disease burden.New strains of influenza viruses also have the potential to cause an influenza pandemic.Due to the high variability and the consequent uncertainty about virus strains,the prevention and control of influenza are faced with many challenges.Surveillance is considered a key strategy to lead to the prevention and control of influenza,and influenza is one of first infectious diseases to be monitored globally.Methods:The Chinese National Influenza Surveillance Network conducts routine influenza surveillance and includes 410 network laboratories and 554 sentinel hospitals based on the requirements of National Influenza Surveillance Guidelines.China and other countries submit epidemiological and virological data to the WHO FluMart database,which can be viewed online.Results:Seasonal influenza H3N2 virus was the dominant subtype in China when entering the 2019–2020 winter influenza season,while neighboring countries such as Japan and Republic of Korea reported the dominance of H1N1pdm09 and Mongolia and Russia reported a higher proportion of type B virus than type A virus.Conclusions and Implications for Public Health Practice:Asian countries entered the 2019–2020 winter influenza season with different type/subtypes of influenza virus dominant in different areas.Influenza surveillance needs to be strengthened to closely monitor changes in the antigenicity and genetic characteristics of emerging viruses.

Distribution of avian influenza viruses according to environmental surveillanee during 2014-2018, China

Background:Recurrent infections of animal hosts with avian influenza viruses(AIVs)have posted a persistent threat.It is very important to understand the avian influenza virus distribution and characteristics in environment associated with poultry and wild bird.The aim of this study was to analyze the geographic and seasonal distributions of AIVs in the 31 provinces,municipalities and autonomous region(PMA)of China,compare the AIVs prevalence in different col-lecting sites and sampling types,analyze the diversity of AIVs subtypes in environment.

Characterization of Influenza Viruses-China, 2019−2020

Introduction:Influenza surveillance is necessary for detection of emerging variants of influenza viruses and determining their epidemiological and clinical significance.Vaccination and antiviral drugs remain the most useful ways to protect against seasonal influenza and its potentially severe consequences.This study describes the epidemiology,antigenic and genetic characteristics,and antiviral susceptibilities of influenza viruses isolated from the mainland of China during the April 1,2019 through October 4,2020.Methods:All viruses analyzed were isolated and submitted by Chinese National Influenza Surveillance Network laboratories.The Chinese National Influenza Center performed antigenic analysis,sequencing,and antiviral resistance testing after propagation of the viruses.Antigenic characterizations were determined by hemagglutinin inhibition assay;next-generation sequencing was used for genetic analyses;phenotypic assay and next-generation sequencing were used for determining antiviral resistance.Results:The influenza positivity rate declined significantly starting in late January 2020 and has remained low.There was no summer influenza peak season in south China.Influenza A(H3N2)and B/Victoria lineage viruses were the dominant subtype/lineage during April 1,2019 through October 4,2020.The majority of influenza viruses were antigenically and genetically similar to reference viruses representing components of vaccines for the 2020–2021 northern hemisphere influenza season.Nearly all seasonal influenza viruses were susceptible to oseltamivir and zanamivir.Conclusions and Implications for Public Health Practice:Since the outbreak of COVID-19,the influenza positivity rate declined with implementation of strong COVID-19 control measures.The majority of circulating viruses are well matched with the current 2020–2021 northern hemisphere influenza vaccine viruses.Circulating seasonal influenza viruses were sensitive to neuraminidase inhibitors and Baloxavir marboxil.This study provided evidence for World Health Organization(WHO)recommendations for vaccine viruses,for prevention and control of influenza,and for clinical use of antiviral medications.