Phylogenetic and histological variation in avipoxviruses isolated in South Africa

Abstract

Thirteen novel avipoxviruses were isolated from birds from different regions of South Africa. These viruses could be divided into six groups, according to gross pathology and pock appearance on chick chorioallantoic membranes (CAMs). Histopathology revealed distinct differences in epidermal and mesodermal cell proliferation, as well as immune cell infiltration, caused by the different avipoxviruses, even within groups of viruses causing similar CAM gross pathology. In order to determine the genetic relationships among the viruses, several conserved poxvirus genetic regions, corresponding to vaccinia virus (VACV) A3L (fpv167 locus, VACV P4b), G8R (fpv126 locus, VLTF-1), H3L (fpv140 locus, VACV H3L) and A11R–A12L (fpv175–176 locus) were analysed phylogenetically. The South African avipoxvirus isolates in this study all grouped in clade A, in either subclade A2 or A3 of the genus Avipoxvirus and differ from the commercial fowlpox vaccines (subclade A1) in use in the South African poultry industry. Analysis of different loci resulted in different branching patterns. There was no correlation between gross morphology, histopathology, pock morphology and phylogenetic grouping. There was also no correlation between geographical distribution and virus phenotype or genotype.

Diversity of avipoxviruses in captive-bred Houbara bustard

“…Classically, APV are considered to be host species or order specific and taxonomy was based on this concept. This has been recently questioned by many authors [4][5][6]23] since some taxa like Columbidae and Accipitridae can be infected by a wide diversity of strains, however with different sensitivity depending on the virus involved. This apparent diversity could be explained by some infections occurring as accidental events, especially in zoological collections where many species are housed closely, and it is suggested that such an infection could not lead to sustainable epornitics [23].…”

“…The complete fpv140 gene sequence (933-1020 bp) was used to build an NJ tree ( Figure 2). Its analysis provided the clades/subclades classification as previously described for clade A [4,5] …”

“…Other genes have been used in order to validate or improve findings based on fpv167. The fpv140 locus (fpv139, fpv140 and fpv141 genes), has also been used [4] and the phylogenetic analyses based on fpv140, orthologous of vaccinia virus H3L gene encoding a virion envelope protein p35, have provided improved strain discrimination within some subclades [5][6][7]. Phylogenetic analyses have all shown the same distribution of APV into 3 clades: fowlpox virus-like (FWPV-like, clade A), canarypox virus-like (CNPV-like, clade B), and psittacinepox virus-like (clade C).…”

AVIAN POXVIRUS INFECTION IN A FLAMINGO (PHOENICOPTERUS RUBER) OF THE LISBON ZOO

“…16 Loci H3L and fpv175-176 have also been used for phylogenetic classification of avipoxviruses. 15 In this study we found that a better discrimination of the isolates can be achieved performing the phylogenetic analysis with a cnpv186-187 concatenated fragment including the 59 end of cnpv186 and the 39 end of cnpv187, instead of the cnpv186 gene alone indicated by Pawar et al 17 Based in this partial encoding sequence, in contrast to the P4b fragment, it was possible to observe a better relationship between the isolates and their host species. The blast analysis revealed that this fragment is more variable than the P4b-encoding sequence, since maximum variability reached 43% in the cnpv186-187 nucleotide sequence and 28% in the P4b-encoding gene.…”

“…There are currently seven subclades within clade A and four subclades within clade B. 5,15 Since one representative of each subclade was included in this analysis, all subclades, A1 to A7 and B1 to B4, are represented and can be identified in the tree (Fig. 4), confirming the findings of Le Loc et al 5 For the phylogenetic analysis based on cnpv186-187 region, the intergenic region was removed, since this noncoding region could have impact on large-scale phylogenetic inference.…”