Application of an equine herpesvirus 1 (EHV1) type-specific ELISA to the management of an outbreak of EHV1 abortion.

This research document explores the use of an ELISA (enzyme-linked immunosorbent assay) that is specific to Equine Herpesvirus 1 (EHV1) in managing an outbreak of EHV1 abortion among Australian thoroughbred mares.

Understanding the Context and Tools Used

• In this study, the researchers examined sera (the clear, watery fluid left behind after coagulation) obtained from 33 Australian Thoroughbred mares during an EHV1-induced abortion outbreak.
• To be able to identify the presence of EHV1-specific antibodies in the sera, the team used an ELISA that was tailored to the virus. This ELISA was characterized by making use of a recombinant EHV1 antigen that originated from glycoprotein G (gG).
• This ELISA was able to differentiate between antibodies specific to EHV1 and those bound to EHV4, a herpesvirus known to be antigenically similar to EHV1 and widespread.

Observations and Findings

• Samples of sera were derived from a majority of these mares in three separate batches; the first was three days after the initial abortion, the second was 13 days after, and the last was 67 days after.
• In order to avoid further spread of the infection, mares that were found without EHV1 antibodies (negative ELISA results) were separated from those that tested positive for the antibodies.
• A couple of days after the first abortion, a second one took place, followed by two more abortions and a perinatal death (occurring around the time of birth). All mares involved in these incidents showed a substantial increase in EHV1-specific antibody by the 13th day, signifying a recent EHV1 infection.
• It was also noted that ten other mares though didn’t have EHV1 antibodies on day 13, had seroconverted (underwent a significant change in antibody levels, indicating a response to infection) to EHV1 by day 67. Interestingly, despite the EHV1 infection, these mares were able to foal normally, possibly because the infection had taken place late in gestation or after foaling.
• Moreover, the study found that of the seven mares that consistently tested negative in the ELISA throughout the sampling period, none experienced abortions. Similarly, none of the 11 mares that tested positive in the initial ELISA tests aborted either.

Conclusion

• This research, therefore, provides inference on the potential role and benefits of using a type-specific ELISA in managing EHV1 disease outbreaks, particularly those that lead to abortion in horses.