Key result
Anti-GnRH vaccination of EAV-carrier stallions significantly reduced semen viral load (P<0.001), with 12 of 15 stallions ceasing to shed the virus between 3 and 10 months.
Why the study?
Stallions are natural reservoirs of equine arteritis virus (EAV) in semen, a testosterone-dependent carrier state that may be reduced by anti-GnRH vaccination.
Does anti-GnRH vaccination reduce EAV viral load and testosterone concentration in stallions shedding EAV in their semen?
Observational (n=16)
Does anti-GnRH vaccination reduce EAV viral load and testosterone concentration in stallions shedding EAV in their semen?
p-value: p=<0.001
Anti-GnRH vaccination significantly reduced testosterone levels and EAV viral shedding in the semen of infected stallions.
May support anti-GnRH vaccination to reduce EAV shedding in stallions; hypothesis-generating and requires controlled trials before practice change.
Stallions are natural reservoirs of equine arteritis virus (EAV) in their semen, representing a potential source of outbreaks. The carrier-state is testosterone-dependent, and clears spontaneously in 4 to 40% stallions. Reduction of testosterone secretion may be obtained with the anti-GnRH vaccine Equity. In this report, 16 naturally infected stallions excreting EAV in their semen were vaccinated twice with the vaccine EquityTM and monitored irregularly under field conditions for EAV viral load in their semen and plasmatic testosterone concentration. The results are indicated in months (M) after the first vaccine injection. Testosterone concentrations decreased from 1.7 to 0.2 ng/mL (P<0.002) after 3M. The EAV viral load decreased from 3.2×109 to 1.1×106 RNA copy/mL of semen (P<0.001) after 5M. One stallion died at 7M for other reason. At M3-10, 12/15 stallions ceased to shed the virus in their semen. At M5-10, 9/15 stallions had plasmatic testosterone concentrations of ≥ 0.5 ng/mL but the 6 others showed a persistently low testosterone concentration (≤0.3 ng/mL). Of the 14 stallions that were expected to recover their reproductive activity at the time of the next breeding season (
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Miszczak et al. (2020) conducted an observational in Equine arteritis virus (EAV) carrier state (n=16). Anti-GnRH vaccine (Equity) was evaluated on EAV viral load in semen (p=<0.001). Anti-GnRH vaccination of EAV-carrier stallions significantly reduced semen viral load (P<0.001), with 12 of 15 stallions ceasing to shed the virus between 3 and 10 months.
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