Avian Influenza Subtype H9N2 Isolated from Various Districts of Punjab Pakistan during 2019?2020

摘要

Avian influenza subtype H9N2 is endemic in Pakistan. The virus being low pathogenic has a low mortality rate but high morbidity rate with huge economic losses in terms of low production. In present study, a total of 500 samples were collected from commercial and backyard poultry of Faisalabad, Toba Tek Singh, Multan, and Bahawalpur districts from September 2019 to February 2020. A total of 39 samples were found to be positive for H9N2 from Faisalabad, Toba Tek Singh, Multan and Bahawalpur which showed an overall prevalence of 7.8%. The samples were further sequenced for HA and NA complete genes and phylogenetic analysis was performed. Results showed that new isolates have close association with recent previous isolates of 2015?2016. The sequence analysis showed that field virus and local vaccine virus has a maximum homology of 98.5 and 99.59% based on HA and NA genes respectively with the field isolates. While imported vaccine viruses have homology with field isolates at a maximum of 89.95 and 90.58% based on HA and NA genes respectively. This shows that vaccines prepared from local field isolates are more successful than the imported vaccines to control H9N2 in the field.