Development of Differentiating Infected from Vaccinated Animals (DIVA) Real-Time PCR for African Horse Sickness Virus Serotype 1

Emerg Infect Dis. 2022 Dec;28(12):2446-2454. doi: 10.3201/eid2812.220594.


African horse sickness (AHS) is a highly infectious and often fatal disease caused by 9 serotypes of the orbivirus African horse sickness virus (AHSV). In March 2020, an AHS outbreak was reported in Thailand in which AHSV serotype 1 was identified as the causative agent. Trivalent live attenuated vaccines serotype 1, 3, and 4 were used in a targeted vaccination campaign within a 50-km radius surrounding the infected cases, which promptly controlled the spread of the disease. However, AHS-like symptoms in vaccinated horses required laboratory diagnostic methods to differentiate infected horses from vaccinated horses, especially for postvaccination surveillance. We describe a real-time reverse transcription PCR-based assay for rapid characterization of the affecting field strain. The development and validation of this assay should imbue confidence in differentiating AHS-vaccinated horses from nonvaccinated horses. This method should be applied to determining the epidemiology of AHSV in future outbreaks.

Keywords: AHSV-1; African horse sickness virus; DIVA assay; Differentiating Infected from Vaccinated Animals; Thailand; vector-borne infections; virology; viruses.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • African Horse Sickness Virus* / genetics
  • African Horse Sickness* / diagnosis
  • African Horse Sickness* / epidemiology
  • African Horse Sickness* / prevention & control
  • Animals
  • Horses
  • Orbivirus*
  • Real-Time Polymerase Chain Reaction
  • Serogroup
  • Vaccines, Attenuated


  • Vaccines, Attenuated