Identification of foot-and-mouth disease virus-free regions by use of a standardized enzyme-linked immunoelectrotransfer blot assay.

OBJECTIVE: To assess the potential of a highly sensitive enzyme-linked immunoelectrotransfer blot (EITB) assay to monitor persistent foot-and-mouth disease (FMD) viral activity in a livestock population. DESIGN: Cattle sera were obtained in Uruguay in 1992, 2 years after the last outbreaks of FMD. Prevalence of antibodies, as assessed by the EITB assay and by the conventional immunodiffusion in agarose gel method (virus infection-associated antigen [VIAA] test), was correlated with occurrence of FMD. SAMPLE POPULATION: A total of 2,194 serum samples were acquired from animals at different farms and were separated according to age: animals < and > 2 years old. PROCEDURE: Specific antibodies to replicating virus were detected by use of the EITB assay that utilizes a set of 5 bioengineered nonstructural antigens as serologic probes. RESULTS: EITB-positive reaction was restricted to sera from cattle in areas with the last outbreaks of FMD during 1989-1990, and to animals > 2 years old. All cattle sera from regions that were free of clinical FMD since (or prior to) 1989 were EITB negative. In contrast, use of the VIAA test yielded a rather homogeneous distribution of positive results when regions without FMD during the last 4 years preceding sample collection were compared with those affected during 1989-1990. VIAA test-positive reaction was also found in sera from animals born after the last FMD outbreak. CONCLUSIONS: The EITB assay proved to be a sensitive, specific, safe, rapid, and economic tool for monitoring the progress of FMD eradication programs, mainly because it eliminated false-positive results form the VIAA test.

Persistencia de anticuerpos anti-VIAA en bovinos vacunados con diferentes vacunas antiaftosa oleosas de uso comercial

Se estudió la persistencia de anticuerpos anti-VIAA en bovinos inmunizados con diferentes vacunas antiaftosa oleosas de uso comercial, utilizadas en la República Oriental del Uruguay. Se processaron 726 sueros de estos animales mediante la técnica de inmunodifusión en gel de agar con antígeno VIA. Se encontró que la detección de anticuerpos anti-VIAA persitió por más de 171 días en animales inmunizados con vacunas de antígeno concentrado con hidróxido de aluminio.

Persistencia de anticuerpos anti-VIAA en bovinos vacunados con diferentes vacunas antiaftosa oleosas de uso comercial / Persistence of anti-VIAA antibodies in cattle vaccinated with different anti-foot-and-mouth disease oil-adjuvant vaccine of commercial use

Se estudió la persistencia de anticuerpos anti-VIAA en bovinos inmunizados con diferentes vacunas antiaftosa oleosas de uso comercial, utilizadas en la República Oriental del Uruguay. Se procesaron 726 sueros de estos animales mediante la técnica de inmunodifusión en gel de agar con antígeno VIA. Se encontró que la detección de anticuerpos anti-VIAA persitió por más de 171 días en animales inmunizados con vacunas de antigeno concentrado con hidróxido de aluminio