Abstract
BackgroundAvian avulavirus (commonly known as avian paramyxovirus-1 or APMV-1) can cause disease of varying severity in both domestic and wild birds. Understanding how viruses move among hosts and geography would be useful for informing prevention and control efforts. A Bayesian statistical framework was employed to estimate the evolutionary history of 1602 complete fusion gene APMV-1 sequences collected from 1970 to 2016 in order to infer viral transmission between avian host orders and diffusion among geographic regions. Ancestral states were estimated with a non-reversible continuous-time Markov chain model, allowing transition rates between discrete states to be calculated. The evolutionary analyses were stratified by APMV-1 classes I (n = 198) and II (n = 1404), and only those sequences collected between 2006 and 2016 were allowed to contribute host and location information to the viral migration networks.ResultsWhile the current data was unable to assess impact of host domestication status on APMV-1 diffusion, these analyses supported the sharing of APMV-1 among divergent host taxa. The highest supported transition rate for both classes existed from domestic chickens to Anseriformes (class I:6.18 transitions/year, 95% highest posterior density (HPD) 0.31–20.02, Bayes factor (BF) = 367.2; class II:2.88 transitions/year, 95%HPD 1.9–4.06, BF = 34,582.9). Further, among class II viruses, domestic chickens also acted as a source for Columbiformes (BF = 34,582.9), other Galliformes (BF = 34,582.9), and Psittaciformes (BF = 34,582.9). Columbiformes was also a highly supported source to Anseriformes (BF = 322.0) and domestic chickens (BF = 402.6). Additionally, our results provide support for the diffusion of viruses among continents and regions, but no interhemispheric viral exchange between 2006 and 2016. Among class II viruses, the highest transition rates were estimated from South Asia to the Middle East (1.21 transitions/year; 95%HPD 0.36–2.45; BF = 67,107.8), from Europe to East Asia (1.17 transitions/year; 95%HPD 0.12–2.61; BF = 436.2) and from Europe to Africa (1.06 transitions/year, 95%HPD 0.07–2.51; BF = 169.3).ConclusionsWhile migration appears to occur infrequently, geographic movement may be important in determining viral diversification and population structure. In contrast, inter-order transmission of APMV-1 may occur readily, but most events are transient with few lineages persisting in novel hosts.
Highlights
Avian avulavirus can cause disease of varying severity in both domestic and wild birds
Presence of virulent Avian paramyxovirus-1 (APMV-1) in poultry is reportable to the World Organisation for Animal Health (OIE) and may result in trade restrictions [20]; understanding the patterns of viral migration between world regions and host types would be useful for efforts directed towards preventing and limiting the spread of Newcastle disease (ND) among wild and domestic birds
All 198 class I sequences were collected after 1997. While this dataset is globally distributed and represents the most comprehensive APMV-1 data available, due to a lack of systematic APMV-1 surveillance and sequencing, many countries with recent Newcastle disease outbreaks are not represented within this analysis (Additional file 2: Figure S1-A)
Summary
Avian avulavirus (commonly known as avian paramyxovirus-1 or APMV-1) can cause disease of varying severity in both domestic and wild birds. APMV-1 of low virulence are capable of evolving naturally into a virulent phenotype; this has been documented only occasionally [14, 15] This suggests that though the initial transmission of wild bird virus into a domestic population may not have significant epidemiological consequences, the repeated transference of virulent viruses between domestic and wild birds likely affects global APMV-1 dynamics. Presence of virulent APMV-1 in poultry is reportable to the World Organisation for Animal Health (OIE) and may result in trade restrictions [20]; understanding the patterns of viral migration between world regions and host types would be useful for efforts directed towards preventing and limiting the spread of ND among wild and domestic birds
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