Natural occurrence of interspecies recombinant viruses between bovine herpesviruses 1 and 5

MAIDANA S. S; ANA MARANDINO; FABRICIO SOUZA CAMPOS; RUBEN PEREZ; P.M. ROEHE; ETIENNE THIRY; ROMERA S.A.

Congreso; World Buiatrics Congress 2018 Sapporo; 2018

Alphaherpesvirinae subfamily members are numerous viral agents of great relevance for ruminant health and production. The large diversity of this subfamily could have been caused by recombination as important mechanism. It can also be hypothesized that this mechanism could be involved in the acquisition of ?new? properties in a viral strain, e.g. a strain with low virulence could acquire characteristics that modify its capacity to induce severe infections. From a viral evolution point of view, recombination can be considered like a driving force essential that would increase the chances to ?channel? rare but advantageous mutations within a viral species. Homologous recombination is based on a high degree of sequence similarity. In the case of ruminant alphaherpesviruses, their degree of genetic similarity has allowed to classify them within a phylogenetic group, where bovine herpesvirus 5 (BoHV5) and bubaline herpesvirus 1 (BuHV1) are closely related to BoHV1, followed by elk herpesvirus 1, cervid herpesviruses 1 and 2, and more distantly to caprine herpesvirus 1. However, even a low degree of similarity between BoHV1 and BoHV5 (82.3% average similarity) allowed, under experimental conditions, the production of the interspecies recombinants BoHV1/5. Recently our group has reported the natural recombination between BoHV1 and BoHV5 viral species based on phylogenetic analysis, multiple PCR sequencing assays and sequence and genetic recombination analysis using a sliding-window genetic diversity plot (Simplot), we found three recombinant field isolates between BoHV1 and BoHV5. Our findings indicate that BoHV5 subtype b, whose current classification by REA is based on the analysis of the three examined field isolates, should rather be considered as a natural recombinant of BoHV5 subtype a and BoHV1 subtype 1.2b. We detected two recombination breakpoints in the open reading frame of the UL27 gene. We showed here the identification of other homologous recombination points between BoHV1 and BoHV5 in this field isolates previously reported.Materials and methods: The complete sequencing of recombinant viral genomes was performed by Next Generation Sequencing (NGS) specifically with the MiSeq technology of Illumina. High-throughput sequencing (HTS) was performed following the manufacturer?s protocol for DNA library construction.Raw sequence reads were trimmed with the aid of Geneious software (version 9.0.5). Assembly and annotation of the viral genome were done using template-assisted assembly, in which trimmed sequences were mapped to the BoHV5 SV507/99 reference genome (accession number NC005261) using Geneious software. After the genetic recombination were analyzed using a sliding-window genetic diversity plot (Simplot software version 3.5.1 available at http://sray.med.som.jhmi.edu/SCRoftware) and the Recombinant Detection Program (RDP), version 3, available at http://darwin.uvigo.es/rdp/ rdp.html).Results: We previously described three recombinant viruses where BoHV1 glycoprotein B gene sequence was present in a BoHV5 genetic background. The complete genome sequencing of two recombinant virus reveal further recombination events. Two additional recombination breakpoints were located in the long unit (UL) genomic region. Based on the BoHV5 genome (GenBank accession number YP003662497.1) one recombination breakpoint is on nt 82881 and the other on 87867 nt giving a recombination fragment of 4986 base pairs showing 100% nucleotidic identity with the BoHV1.2b subtype genome. Our results support the hypothesis that the occurrence of a first recombination event positively influences the occurrence of a second recombination event in a neighboring regionConclusions: we identify recombinant ruminant alphaherpesviruses and provide evidence of the existence of natural recombinants and recombination events within distinct viral species in the subfamily Alphaherpesvirinae infecting ruminants. Recombination should be now investigated with regards to its impact on differential diagnosis methods, the risk to escape vaccine-induced immunity and pathogenesis of infections.