Relationship between onset of puberty and establishment of persistent infection with equine arteritis virus in the experimentally infected colt.

This study explores how the maturity of a horse’s reproductive system impacts its susceptibility to a persistent infection of equine arteritis virus (EAV). The researchers recommend vaccinating colts at around six months old, prior to puberty but after the disappearance of antibodies inherited from the mother.

Study Design and Participants

• The study was designed to investigate the relationship between the maturity stage of a colt’s reproductive tract and its susceptibility to a prolonged infection with the Equine Arteritis Virus. For the experiment, the researchers chose 21 prepubertal and 15 peripubertal colts.
• The colts were inoculated with EAV, and their infection status was monitored over several months. The researchers divided the monitoring for prepubertal colts into several timelines: 28 to 93 days, 120 to 180 days, and 210 days post-challenge.

Results

• Of the prepubertal colts, five out of the six that were inoculated remained infected from 28 to 93 days post-challenge, whereas two out of six remained infected from 120 to 180 days post-challenge. However, no virus was detected in any of those animals after 210 days post-challenge.
• Among the peripubertal colts, each of the two colts remained infected at the 60-day post-challenge mark. Furthermore, the infection was detected in one of the nine colts, 15 months after the challenge

Conclusions and Suggestions

• The results confirmed that EAV can replicate in the reproductive tract of a significant number of colts for an extended period after clinical recovery.
• Long-term persistent virulent infection, however, does not appear to occur in colts exposed to the virus before the onset of peripubertal development. This suggests a possible protective mechanism triggered by puberty.
• As a result, the researchers recommend that colts should be vaccinated against EAV around six months of age. This is after the inherited maternal antibodies have disappeared but before the onset of puberty.