The effect of age on the excretion of ovine herpesvirus-2 (OvHV-2), the causative agent of malignant catarrhal fever (MCF), in naturally infected sheep.

Abstract

Malignant catarrhal fever (MCF) is one of the most important viral diseases affecting cattle and buffaloes. One of the viruses associated with this disease is ovine herpesvirus 2 (OvHV-2), which is responsible for sheep-associated MCF. Sheep serve as the reservoir host for OvHV-2, transmitting the virus susceptible species such as buffaloes and cattle. Virus shedding in sheep is thought to be age-dependent. Therefore, this study aimed to investigate OvHV-2 infection in sheep and determine the age at which virus excretion occurs. For this purpose, 191 female sheep from four suburbs of Ahvaz were studied. The studied sheep were female and according to incisors teeth formula divided into six age groups; 3-< 6, 6-< 12 months to 1, 2, 3,and ≥ 4 years. Blood and nasal swab samples were taken from each animal. Buffy coats were removed from the blood samples, and DNA extraction were performed from buffy coats and swab sample. Semi-nested PCR was used to detect OvHV-2 DNA. The PCR results showed that 89.5 % of blood samples and 78.5 % of nasal swabs were positive for OvHV-2. Nasal excretion of the virus was observed across all ages groups, though the frequency varied with age. A significant correlation was found between presence of virus in blood and detection of virus in nasal swap samples. In conclusion, sheep of all ages are capable to excretion OvHV-2 through nasal secretion, posing a risk of infecting susceptible animals.