Presence of Vaccine-Derived Newcastle Disease Viruses in Wild Birds

Abstract

Our study demonstrates the repeated isolation of vaccine-derived Newcastle disease viruses from different species of wild birds across four continents from 1997 through 2014. The data indicate that at least 17 species from ten avian orders occupying different habitats excrete vaccine-derived Newcastle disease viruses. The most frequently reported isolates were detected among individuals in the order Columbiformes (n = 23), followed in frequency by the order Anseriformes (n = 13). Samples were isolated from both free-ranging (n = 47) and wild birds kept in captivity (n = 7). The number of recovered vaccine-derived viruses corresponded with the most widely utilized vaccines, LaSota (n = 28) and Hitchner B1 (n = 19). Other detected vaccine-derived viruses resembled the PHY-LMV2 and V4 vaccines, with five and two cases, respectively. These results and the ubiquitous and synanthropic nature of wild pigeons highlight their potential role as indicator species for the presence of Newcastle disease virus of low virulence in the environment. The reverse spillover of live agents from domestic animals to wildlife as a result of the expansion of livestock industries employing massive amounts of live virus vaccines represent an underappreciated and poorly studied effect of human activity on wildlife.

Reverse spillover of avian viral vaccine strains from domesticated poultry to wild birds

“…However, it is likely that APMV1 strains could infect any bird species due to broader host spectrum of these viruses [20,21]. While this and previous studies [2,4,5] have highlighted the reverse spillover, it is yet to be determined if these spilled over viruses retain their immunization potential or in the event of concurrent infection may lead to virus evolution and altered pathogenicity.…”

“…These viral vaccinestrains isolated from wild birds have shown significant genetic similarities with the vaccine strains being applied in the commercial poultry farms suggesting the possible reverse spillover of these viruses to nearby wild life. These findings highlight the need to fully investigate the dynamics and spectrum of vaccine-derived viral strains in wild birds and that such virus detection would severely jeopardise the welfare of the wild birds and may in future leads to virus evolution with increased virulence, as has been proposed for avian influenza viruses [1,2].…”

“…Wild birds have been proposed to play crucial roles in the spillover and in potentiating the virulence of avian viruses [2]. However, intensive vaccines application, contamination of the environment with infectious material through disposal or re-use of poultry litter and due to close contacts between wild birds and commercial poultry may lead to reversal of spillover (reverse spillover) from farmed poultry to wild birds [3].…”

“…Likewise, the transmission of virulent (e.g. escape mutant) viruses that have evolved either in response to vaccine pressure or through undetected viral contaminants within commercial vaccines are being transmitted to wild birds [2]. In high-tech commercial poultry farming, the possibility of spillover scenario into wild birds can be mitigated by the strict biosecurity measures.…”

Complete Genome Sequence of a Vaccinal Newcastle Disease Virus Strain Isolated from an Owl ( Rhinoptynx clamator )

“…Pathogens can be transmitted from domestic animals to free-ranging hosts and vice versa (12, 13). Indeed, the continuous expansion of the poultry industry coupled with the mass employment of live-virus vaccines (14) may result in a spillover of vaccinal strains to wildlife reservoirs (15). The impact of these vaccinal strains in wildlife reservoirs remains unknown.…”