First Molecular Evidence and Genetic Characterization of Ovine Herpesvirus 2 in Multiple Animal Species in India.

Naveen Kumar,R Ramprabhu,Atul K Pateriya,Roma Dixit,Vijendra Pal Singh,Sandeep Bhatia,Richa Sood,E Venkatesakumar

doi:10.3389/fvets.2021.610178

Abstract

Ovine herpesvirus 2 (OvHV-2) is the causative agent of sheep-associated malignant catarrhal fever (SA-MCF), a highly fatal disease syndrome that predominantly affects susceptible hosts of the order Artiodactyla. In this study, an in-depth clinico-molecular investigation of SA-MCF disease in a morbid 50-days-old cattle calf (Bos taurus indicus) and asymptomatic infection in the in-contact reservoir hosts, sheep (Ovis aries), and goat (Capra hircus) housed on a farm located in the Southern India is reported. An OIE recommended SA-MCF type-specific PCR confirmed the etiological agent as OvHV-2. The genetic characterization and phylogenetic analyses based on the glycoprotein B (gB) gene indicate that three genetic variants of OvHV-2 had infected the animal cluster of this study. As the OvHV-2 infection eventually lead to the death of the cattle calf, and the fact that its gB sequence carried four unique amino acid substitutions (N169S, L594P, I645V, and V730A), an investigation of these substitutions impact on its stability and molecular flexibility was carried out. The mapping of these amino acid substitutions on the three-dimensional structure of gB coupled with supplementary investigations showed that these substitutions conveyed the molecular flexibility to the gB, at the cost of its stability. Future studies would be to investigate whether these gB substitutions have any impact on membrane fusion activity using a virus-free cell-to-cell membrane fusion assay. The study also highlights the importance of adopting stringent biosecurity measures where mixed animal farming is a common practice.

Highlights

Malignant catarrhal fever (MCF) is a highly fatal, lymphoproliferative disease syndrome in the susceptible hosts of the order Artiodactyla, such as cattle, bison, deer, swine, and water buffalo [1]
We report an investigation of SA-MCF disease in a cattle calf and asymptomatic infection in the in-contact reservoir hosts that occurred on a farm located at Tirunelveli, Tamil Nadu, India
A 50-days-old cattle calf suffering from high fever (40◦C), anorexia, serous nasal, and ocular discharge was referred to the Teaching Veterinary Clinical Complex, Veterinary College and Research Institute, Tirunelveli, TamilNadu, India and received a treatment regimen consisting of Ringer’s lactate (5 ml/kg i.v.), Dextrose normal saline (5 ml/kg i.v.), Flunixin meglumine (1.1 mg/kg), and a combination of Amoxicillin and Clavulanic acid (12.5 mg/kg BID i.v.) for 7 days

Summary

Introduction

Malignant catarrhal fever (MCF) is a highly fatal, lymphoproliferative disease syndrome in the susceptible hosts of the order Artiodactyla, such as cattle, bison, deer, swine, and water buffalo [1]. Six viruses of the genus Macavirus of the Gammaherpesvirinae subfamily cause the MCF disease and these viruses include alcelaphine herpesvirus-1 (AIHV-1), ovine herpesvirus-2 (OvHV-2), caprine herpesvirus-2 (CpHV-2), alcelaphine herpesvirus-2, ibex malignant catarrhal fever virus, and a virus causing MCF in the deer [2]. OvHV-2 is Genetic Characterization of Ovine Herpesvirus 2 responsible for sheep-associated-MCF (SA-MCF) disease in susceptible hosts such as buffalo [3], cattle [4], deer [5], and rarely in pig [6], and foal [7]. Perivascular cuffing is considered as an important feature for the tentative diagnosis of SA-MCF disease [8]

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Conclusion