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.


METHODS
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.


METHODS
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.


METHODS
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.
Bergmann
I E
IE
Pan American Foot-and-Mouth Disease Center (PAHO/WHO), Rio de Janeiro, Brazil.
Malirat
V
V
Dias
L E
LE
Dilandro
R
R
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood; D000918:Antibody Specificity; D005537:Aphthovirus / Q000276:immunology / Q000302:isolation & purification* / Q000502:physiology; D002417:Cattle; D004196:Disease Outbreaks / Q000662:veterinary; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005536:Foot-and-Mouth Disease / Q000453:epidemiology*; D005843:Geography; D014583:Uruguay / Q000453:epidemiology; D017361:Viral Nonstructural Proteins / Q000276:immunology; D014779:Virus Replication
D000914:Antibodies, Viral; D017361:Viral Nonstructural Proteins