Hussey SB, Clark R, Lunn KF, Breathnach C, Soboll G, Whalley JM, Lunn DP. Detection and quantification of equine herpesvirus-1 viremia and nasal shedding by real-time polymerase chain reaction.
J Vet Diagn Invest 2006;
18:335-42. [PMID:
16921871 DOI:
10.1177/104063870601800403]
[Citation(s) in RCA: 72] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
Equine herpesvirus-1 (EHV-1) infection is common in young horses throughout the world, resulting in respiratory disease, epidemic abortion, sporadic myelitis, or latent infections. To improve on conventional diagnostic tests for EHV-1, a real-time polymerase chain reaction (PCR) technique was developed, using primers and probes specific for the EHV-1 gB gene. Amplification efficiencies of 100% +/- 5% were obtained for DNA isolated from a plasmid, infected peripheral blood mononuclear cells (PBMCs), and nasal secretions from infected ponies. The dynamic range of the assay was 8 log10 dilutions, and the lower limit of detection was 6 DNA copies. Fifteen ponies, seronegative for EHV-1, were experimentally infected with EHV-1, and nasal samples were used to quantify shedding of virus by both virus isolation and real-time PCR analysis. Virus isolation identified nasal shedding of EHV-1 in 12/15 ponies on a total of 25 days; real-time PCR detected viral shedding in 15/15 ponies on 75 days. Viremia was quantified using PBMC DNA, subsequent to challenge infection in 3 additional ponies. Viremia was identified in 1/3 ponies on a single day by virus isolation; real-time PCR detected viremia in 3/3 ponies on 17 days. When real-time PCR was used to analyze PBMC DNA from 11 latently infected ponies (documented by nested PCR), EHV-1 was not detected. We conclude that real-time PCR is a sensitive and quantitative test for EHV-1 nasal shedding and viremia and provides a valuable tool for EHV-1 surveillance, diagnosis of clinical disease, and investigation of vaccine efficacy.
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