Simultaneous Detection of Velogenic Genotype XIII 2.2 Avian Avulavirus Type 1 (AAvV-1) From Spot-billed Pelican and Backyard Chicken: Implications to the Viral Maintenance and Spread
Abstract The present study demonstrates simultaneous isolation of genetically similar velogenic Avian Avula virus-1 from an apparently healthy spot- billed pelican and a naturally infected backyard chicken in the adjacent vicinity. A total of fourty eight cloacal swab samples from migratory birds (Painted storks, n=32 and Spot billed pelicans, n=16) at the Telineelapuram bird sanctuary in Andhra Pradesh, India and tissue samples of dead backyard chicken were collected. Two isolates were recovered, one each from a spot billed pelican (MIG-9) and a dead chicken (SKLM-1). The isolates were confirmed as velogenic based on mean death time, intra cerebral pathogenicity index and the putative fusion protein cleavage site (113R-R-K-R-F117). Phylogenetic analysis based on full- length fusion and attachment (HN) proteins classified the isolates into genotype XIII, sub- genotype 2.2. Sequence analysis revealed that the pelican and chicken isolates were 100% identical. The study isolates demonstrated multiple amino acid substitutions at several critical domains of F and HN proteins when compared with the current vaccine strains. Pathogenic and transmission potential of the AAvV-1 isolates was evaluated in three- week old chicken and the isolates proved to be highly virulent to chicken. To the best of our knowledge, this is the first evidence for the role of spot-billed pelicans in the maintenance of virulent AAvV-1 and its transmission to chicken. This study further highlights the role of wild birds in AAvV-1 transmission and the need for enhanced biosecurity in commercial poultry operations.