Genetic characterization of astroviruses detected in guinea fowl (Numida meleagris) reveals a distinct genotype and suggests cross-species transmission between turkey and guinea fowl

Abstract

Astroviruses can infect mammalian and avian species and are often responsible for gastroenteric disease symptoms. In this study, the complete open reading frame (ORF) 2, the 3' end of ORF1b and the corresponding intergenic region of astroviruses identified in farmed guinea fowl (Numida meleagris) were sequenced and genetically analysed. Overall, the genetic sequence of guinea fowl astroviruses was related to turkey astrovirus type 2 (TastV2), although a marked genetic distance was revealed based on ORF2, which might indicate the circulation of a distinct virus genotype and serotype in guinea fowl. Furthermore, the genetic data presented herein suggest that either recombination between different astroviruses infecting distinct hosts or adaptation of a given astrovirus to a new host had occurred. In either case, direct or indirect interspecies transmission of astroviruses is likely to have occurred between turkey and guinea fowl, indicating the ability of viruses belonging to the family Astroviridae to cross species barriers.

Experimental infection of poults and guinea fowl with genetically distinct avian astroviruses

“…To date, no documented interspecies transmission has been reported but in this study we have provided, for the first time, experimental evidence of cross-infection of two different avian species with two genetically different avastroviruses. This evidence associated with the detailed genetic characterization of these viruses (De Battisti et al, 2012) sheds new light on the ecology of avian astroviruses and contributes to a better understanding of mechanisms at the base of recombination and genetic diversity of astroviruses.…”

“…Briefly, viral RNA was extracted using commercial kits (NucleoSpin RNA II; Macherey-Nagel, Duren, Germany), according to the manufacturer's instructions. A one-step RT-PCR was performed using the Qiagen RT-PCR kit (Qiagen, Inc., Valencia, California, USA) to amplify TAstV2 ORF1b according to the protocol developed by Koci et al (2000a) and new sets of primers were designed to target ORF2 of GFAstV (De Battisti et al, 2012).…”

“…Although grouped separately in phylogenetic trees based on the open reading frame (ORF) 1b (viral RNAdependent RNA polymerase, RdRp) gene sequences, the guinea fowl astrovirus (GFAstV) appeared closely related to TAstV2, and for this reason the possibility of interspecies transmission between turkey and guinea fowl was proposed (Cattoli et al, 2007;De Battisti et al, 2012). On the other hand, sequences of the ORF2 gene, coding for the capsid protein of TAstV2 and GFAstV, imply a high level of divergence between these two viruses (De Battisti et al, 2012). According to standard astrovirus classification, based on the species of origin, GFAstV can actually be proposed as a new species.…”

Crystal Structure of the Avian Astrovirus Capsid Spike

“…Our predicted structural similarity in all avian capsid spike domains suggests that one or more mutations may be sufficient to compose a receptor-binding pocket for a new avian species. There is already evidence for avianto-avian astrovirus transmission between turkeys and ducks (6) or guinea fowl (51,52) and between chickens and pigeons (53), water fowl (54), or ducks (55).…”

Ecological Drivers of Virus Evolution: Astrovirus as a Case Study

“…This is common with poultry (domestic ducks, chickens, turkeys, and guinea fowl), where coreared and free-ranging birds can interact with each other and with foraging wild birds. This can lead to coinfection with different strains and opportunities for recombination, evidenced by viruses detected in guinea fowl that originated in turkeys or those detected in domestic ducks that are turkey and chicken derived (13,14). Ecotones also drive zoonoses, as evidenced by seroconversion of farmers and infection of an immunocompromised individual (15,16).…”