Highly Pathogenic H5 Influenza Viruses Isolated between 2016 and 2017 in Vietnamese Live Bird Markets

Routine surveillance in live poultry markets in the northern regions of Vietnam from 2016 to 2017 resulted in the isolation of 27 highly pathogenic avian H5N1 and H5N6 viruses of 3 different clades (2.3.2.1c, 2.3.4.4f, and 2.3.4.4g). Sequence and phylogenetic analysis of these viruses revealed reassortment with various subtypes of low pathogenic avian influenza viruses. Deep-sequencing identified minor viral subpopulations encoding variants that may affect pathogenicity and sensitivity to antiviral drugs. Interestingly, mice infected with two different clade 2.3.2.1c viruses lost body weight rapidly and succumbed to virus infection, whereas mice infected with clade 2.3.4.4f or 2.3.4.4g viruses experienced non-lethal infections.

Automated summary

Surveillance in Vietnam's northern live poultry markets identified 27 highly pathogenic avian influenza H5N1 and H5N6 viruses from 2016 to 2017, belonging to 3 different clades. Sequencing and phylogenetic analysis revealed reassortment with low pathogenic avian influenza viruses and identified minor viral subpopulations encoding variants that may affect pathogenicity and antiviral drug sensitivity. Mice infected with clade 2.3.2.1c viruses rapidly lost weight and died, while those infected with clade 2.3.4.4f or 2.3.4.4g experienced non-lethal infections.