Monitoring of the shedding and serological dynamics of Bovine gammaherpesvirus type 4 in a dairy cattle herd

Vet Microbiol. 2019 Dec;239:108495. doi: 10.1016/j.vetmic.2019.108495. Epub 2019 Nov 2.

Abstract

Bovine gammaherpesvirus type 4 (BoHV-4) is increasingly related with reproductive disease in cattle, but its epidemiology is not fully understood. We monitored the serological response and shedding of BoHV-4 in a positive dairy cattle farm with metritis. First, we performed an ELISA to detect BoHV-4 antibodies in all the animals (n = 104). Afterwards, ten seronegative heifers introduced in the production lot and sera samples were monthly taken for four months and then 6-10 months after introduction to detect BoHV-4 antibodies by ELISA. Moreover, a vaginal swab was taken after calving to detect BoHV-4 by PCR. Concurrently, a weekly collection of vaginal and nasal swabs and milk was performed during the first month post-partum in multiparous cows with metritis (n = 14), heifers with metritis (n = 4), heifers without metritis but positive to BoHV-4 (ELISA or PCR) (n = 2) and multiparous cows without metritis (n = 3). Seropositivity was higher in older animals and in the production lot. Three heifers which shed BoHV-4 after parturition resulted seronegative at first but eventually seroconverted. In the same vein, most heifers seroconverted after 6-10 months in the production lot (8/10). Multiparous cows shed virus by various routes: 13/14 (93 %) in vaginal secretions, 7/14 (50 %) in nasal exudates and 7/14 (50 %) in milk. However, in the other groups, shedding was only detected in vaginal swabs from the first week post-partum. Our study describes BoHV-4 shedding in field conditions. Seronegative animals may become horizontally infected when moved to a contaminated environment.

Keywords: BoHV-4; Cattle; Heifers; PCR; Serology.

MeSH terms

  • Animals
  • Antibodies, Viral / blood*
  • Cattle
  • Female
  • Herpesviridae Infections / blood
  • Herpesviridae Infections / immunology
  • Herpesviridae Infections / veterinary*
  • Herpesviridae Infections / virology
  • Herpesvirus 4, Bovine / physiology*
  • Postpartum Period
  • Seroconversion
  • Tumor Virus Infections / blood
  • Tumor Virus Infections / immunology
  • Tumor Virus Infections / veterinary*
  • Tumor Virus Infections / virology
  • Vagina / virology
  • Virus Shedding*

Substances

  • Antibodies, Viral