Whole Genome Sequencing of a Canadian Bovine Gammaherpesvirus 4 Strain and the Possible Link between the Viral Infection and Respiratory and Reproductive Clinical Manifestations in Dairy Cattle

Abstract

Bovine gammaherpesvirus 4 (BoHV-4) is a herpesvirus widespread in cattle populations, and with no clear disease association. Its genome contains a long unique coding region (LUR) flanked by polyrepetitive DNA and 79 open reading frames (ORFs), with unique 17 ORFs, named Bo1 to Bo17. In 2009, a BoHV-4 strain was isolated (FMV09-1180503: BoHV-4-FMV) from cattle with respiratory disease from Quebec, Canada, and its LUR was sequenced. Despite the overall high similarity, BoHV-4-FMV had the most divergent LUR sequence compared to the two known BoHV-4 reference strain genomes; most of the divergences were in the Bo genes and in the repeat regions. Our phylogenetic analysis based on DNA polymerase and thymidine kinase genes revealed that virus isolate was BoHV-4 gammaherpesvirus and clustered it together with European BoHV-4 strains. Because BoHV-4-FMV was isolated from animals presenting respiratory signs, we have updated the BoHV-4 Canadian cattle seroprevalence data and tried to find out whether there is a link between clinical manifestation and BoHV-4 seropositivity. An indirect immunofluorescence assay (IFA) was performed with nearly 200 randomized sera of dairy cattle from two Canadian provinces, Quebec (n = 100) and Ontario (n = 91). An additional set of sera obtained from Quebec, from the healthy (n = 48) cows or from the animals experiencing respiratory or reproductive problems (n = 75), was also analyzed by IFA. BoHV-4 seroprevalence in Canadian dairy cattle was 7.9% (Quebec: 6% and Ontario: 9.9%). Among animals from the Quebec-based farms, diseased animals showed higher BoHV-4 seropositivity than healthy animals (P < 0.05), with a significant 2.494 odds ratio of being seropositive in sick compared to healthy animals. Although there is no established direct link between BoHV-4 and specific diseases, these seroprevalence data suggest the possible involvement of BoHV-4 in dairy cattle diseases.

OvHV-2 Glycoprotein B Delivered by a Recombinant BoHV-4 Is Immunogenic and Induces Partial Protection against Sheep-Associated Malignant Catarrhal Fever in a Rabbit Model

“…As expected, based on previous studies using rabbits as a model for BoHV-4 infection, BoHV-4-A∆TK-OvHV-2-gB was safe and no adverse effects developed in any animal. Although BoHV-4 is considered by some to be a pathogen in cattle [ 20 , 21 ], its natural host, such effects have not been confirmed or demonstrated experimentally [ 22 , 23 , 24 ]. This suggests that its pathogenicity may be secondary to other agents.…”

Bovine herpes virus type-4 infection among postpartum dairy cows in California: risk factors and phylogenetic analysis

“…2) indicates that the genotype could be involved in causing respiratory infection in addition to uterine infection. The reference strain BoHV-4-FMV-09 has recently been found to be associated with respiratory disease from Quebec, Canada [38]. Furthermore, gB genotype 1 (Fig.…”

“…Furthermore, isolation of various BoHV-4 genotypes from post-partum metritis in California dairy cows highlights the importance of further research since this will eventually be helpful for vaccine development in the future. It is possible that genetic diversity of strains for a pathogenic virus can be a factor for potential difference in the pathogenicity of strains [38].…”

IDENTIFICATION AND MOLECULAR CHARACTERIZATION OF BOVINE HERPERVIRUSES (BoHV) DNA TERMINASE PARTIAL GENE IN ACEH CATTLE

“…The virus causes disease in cattle and infected cattles may suffer from abortion, low milk production, respiratory symptoms, low birth weight of neonates, and infertility (Muylkens et al, 2007;Yildirim et al, 2011). BoHV specieses that are known as pathogen in cattle are BoHV-1, BoHV-2, BoHV-4, BoHV-5, and BoHV-6 (Campos et al, 2014;Gagnon et al, 2017;Aslan et al, 2015).…”