Phylogenetic Characterization of the Palyam Serogroup Orbiviruses.

Karen Ebersohn,Estelle H. Venter,Robert Swanepoel,Louwrens P. Snyman,Peter Coetzee

doi:10.3390/v11050446

Karen Ebersohn, Estelle H. Venter + Show 3 more

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https://doi.org/10.3390/v11050446

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Abstract

The Palyam serogroup orbiviruses are associated with abortion and teratogenesis in cattle and other ruminants. Of the 13 different serotypes that have been identified, the full genome sequence of only one, Kasba, has been published. We undertook to perform Next Generation Sequencing (NGS) and phylogenetic analysis on 12 Palyam serotypes plus field isolates of the African serotypes in our possession. The Palyam serogroup was found to be most closely related to the African horse sickness virus group and showed the most distant evolutionary relationship to the equine encephalosis viruses (EEV). Amino acid sequence analysis revealed that the gene encoding VP7 was the most conserved within serotypes and VP2 and VP5 showed the highest degree of variation. A high degree of sequence identity was found for isolates from the same geographical region. The phylogenetic analysis revealed two clades where the African serotypes were all very closely related in one clade and the other clade contained the Australian and Asian serotypes and one African serotype, Petevo. It was evident from the sequence data that the geographical origin of Palyam serogroup viruses played an important role in the development of the different serotypes.

Highlights

The Palyam serogroup of the genus Orbivirus and family Reoviridae are arthropod-borne viruses that have been isolated in Asia, Africa, and Australia [1,2]
Sufficient quantities of the original samples were not available to repeat the sequencing or to design primers to complete the entire region with conventional sequencing
The high-sequence identity that exists between the viruses from Australia and Asia may suggest that there has been some gene-flow between the serotypes, possibly due to the cattle from

Summary

Introduction

The Palyam serogroup of the genus Orbivirus and family Reoviridae are arthropod-borne viruses that have been isolated in Asia, Africa, and Australia [1,2]. Some of the viruses are associated with abortion and teratogenesis in cattle and other ruminants [3,4,5,6]. Some Palyam serogroup viruses had been isolated previously from aborted foetuses [7,8], it was only after an outbreak of congenital abnormalities in cattle in Japan in 1985–1986 that their pathogenic importance was investigated [6,9]. The Palyam viral genome is similar to that of other orbiviruses, which notably include viruses like bluetongue virus (BTV), epizootic haemorrhagic disease virus (EHDV), and African horse sickness virus (AHSV). The genome consists of ten linear double-stranded (ds) RNA segments that code for seven structural viral proteins (VP1 to VP7) and four non-structural proteins

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