Genetic and Antigenic Characterization of Avian Avulavirus Type 6 (AAvV-6) Circulating in Canadian Wild Birds (2005–2017)

Tamiko Hisanaga,Oliver Lung,Matthew Suderman,Nicola Lewis,Catherine Soos,Yohannes Berhane

doi:10.3390/v13040543

Abstract

We describe for the first time the genetic and antigenic characterization of 18 avian avulavirus type-6 viruses (AAvV-6) that were isolated from wild waterfowl in the Americas over the span of 12 years. Only one of the AAvV-6 viruses isolated failed to hemagglutinate chicken red blood cells. We were able to obtain full genome sequences of 16 and 2 fusion gene sequences from the remaining 2 isolates. This is more than double the number of full genome sequences available at the NCBI database. These AAvV-6 viruses phylogenetically grouped into the 2 existing AAvV-6 genotype subgroups indicating the existence of an intercontinental epidemiological link with other AAvV-6 viruses isolated from migratory waterfowl from different Eurasian countries. Antigenic maps made using HI assay data for these isolates showed that the two genetic groups were also antigenically distinct. An isolate representing each genotype was inoculated in specific pathogen free (SPF) chickens, however, no clinical symptoms were observed. A duplex fusion gene based real-time assay for the detection and genotyping of AAvV-6 to genotype 1 and 2 was developed. Using the developed assay, the viral shedding pattern in the infected chickens was examined. The chickens infected with both genotypes were able to shed the virus orally for about a week, however, no significant cloacal shedding was detected in chickens of both groups. Chickens in both groups developed detectable levels of anti-hemagglutinin antibodies 7 days after infection.

Highlights

Avian avulaviruses are some of the most commonly found viruses infecting a wide variety of domestic and wild birds worldwide [1]
Eighteen swab samples collected between 2005 and 2017 from wild waterfowl that initially tested positive for the presence of influenza A virus genomic material by realtime reverse transcriptase PCR (RT-PCR) assay were inoculated into 9-day-old specific pathogen free (SPF) embryonating chicken eggs
The allantoic fluids (AAF) collected from this sample at the end of 2nd passage tested positive by hemagglutination activity (HA) assay

Summary

Introduction

Avian avulaviruses are some of the most commonly found viruses infecting a wide variety of domestic and wild birds worldwide [1]. All viruses belonging to the Avulavirinae subfamily are pleomorphic, enveloped, single stranded and non-segmented viruses containing a negative sense RNA genome of 10–17 Kb size [1]. The RNA genome of avulaviruses encode six structural proteins (NP, P, M, F, HN, and L) and through RNA editing, two non-structural proteins (V and W) [1,2]. Avulaviruses have two surface spike glycoproteins, the hemagglutininneuraminidase (HN) and the fusion (F) protein. The hemagglutinin part of the HN spike protein is responsible for the attachment of virions to the sialic acid containing receptors on the surface of cells and the neuraminidase part has the receptor-destroying activity [3]

Methods

Results

Conclusion