Multiplexed molecular assay for rapid exclusion of foot-and-mouth disease.

A nucleic acid-based multiplexed assay was developed that combines detection of foot-and-mouth disease virus (FMDV) with rule-out assays for two other foreign animal diseases and four domestic animal diseases that cause vesicular or ulcerative lesions indistinguishable from FMDV infection in cattle, sheep and swine. The FMDV "look-alike" diagnostic assay panel contains 5 PCR and 12 reverse transcriptase PCR (RT-PCR) signatures for a total of 17 simultaneous PCR amplifications for 7 diseases plus incorporating 4 internal assay controls. It was developed and optimized to amplify both DNA and RNA viruses simultaneously in a single tube and employs Luminex liquid array technology.

Diagnostic evaluation of multiplexed reverse transcription-PCR microsphere array assay for detection of foot-and-mouth and look-alike disease viruses.

A high-throughput multiplexed assay was developed for the differential laboratory detection of foot-and-mouth disease virus (FMDV) from viruses that cause clinically similar diseases of livestock. This assay simultaneously screens for five RNA and two DNA viruses by using multiplexed reverse transcription-PCR (mRT-PCR) amplification coupled with a microsphere hybridization array and flow-cytometric detection. Two of the 17 primer-probe sets included in this multiplex assay were adopted from previously characterized real-time RT-PCR (rRT-PCR) assays for FMDV.

Potential impact of an introduction of foot-and-mouth disease into the California State Fair.

Objective: To estimate the potential spread of foot-and-mouth disease (FMD) if infected livestock had been exhibited at the 2005 California State Fair.

Design: Epidemic model.

Animals: Dairy cattle, dairy goats, and pygmy goats exhibited between August 24 and August 28 by 195 exhibitors.

Incidence and effects of West Nile virus infection in vaccinated and unvaccinated horses in California.

A prospective cohort study was used to estimate the incidence of West Nile virus (WNV) infection in a group of unvaccinated horses (n = 37) in California and compare the effects of natural WNV infection in these unvaccinated horses to a group of co-mingled vaccinated horses (n = 155). Horses initially were vaccinated with either inactivated whole virus (n = 87) or canarypox recombinant (n = 68) WNV vaccines during 2003 or 2004, prior to emergence of WNV in the region. Unvaccinated horses were serologically tested for antibodies to WNV by microsphere immunoassay incorporating recombinant WNV E protein (rE MIA) in December 2003, December 2004, and every two months thereafter until November 2005.

Detection of antibodies to West Nile virus in equine sera using microsphere immunoassay.

One hundred and ninety-one sera from horses that recently were exposed to West Nile virus (WNV) by either vaccination or natural infection or that were not vaccinated and remained free of infection were used to evaluate fluorescent microsphere immunoassays (MIAs) incorporating recombinant WNV envelope protein (rE) and recombinant nonstructural proteins (rNS1, rNS3, and rNS5) for detection of equine antibodies to WNV. The rE MIA had a diagnostic sensitivity and specificity, respectively, of 99.3% and 97.

Environmental air sampling to detect exotic Newcastle disease virus in two California commercial poultry flocks.

The 2002--2003 Exotic Newcastle Disease (END) outbreak in Southern California poultry provided an opportunity to evaluate environmental air sampling as an efficient and cost-effective means of sampling flocks for detection of a circulating virus. Exotic Newcastle Disease virus was detected by real-time reverse transcriptase PCR from air samples collected using a wetted-wall cyclone-style air sampler placed within 2 m of birds in 2 commercial flocks suspected of being naturally exposed to END virus during the outbreak. Exotic Newcastle Disease virus was detected after 2 hours of air sampling the poultry-house environments of the 2 naturally infected flocks.

Alphavirus replicon particles expressing the two major envelope proteins of equine arteritis virus induce high level protection against challenge with virulent virus in vaccinated horses.

Replicon particles derived from a vaccine strain of Venezuelan equine encephalitis (VEE) virus were used as vectors for expression in vivo of the major envelope proteins (G(L) and M) of equine arteritis virus (EAV), both individually and in heterodimer form (G(L)/M). The immunogenicity of the different replicons was evaluated in horses, as was their ability to protectively immunize horses against intranasal and intrauterine challenge with a virulent strain of EAV (EAV KY84). Horses immunized with replicons that express both the G(L) and M proteins in heterodimer form developed neutralizing antibodies to EAV, shed little or no virus, and developed only mild or inapparent signs of equine viral arteritis (EVA) after challenge with EAV KY84.