Evaluation of a Semiautomated Latex Agglutination Test for the Detection of Pseudorabies Antibody in Swine Sera

Abstract

Abstract. Rapid screening of large numbers of swine sera for antibody is an essential element in the current eradication program for pseudorabies in the United States. We evaluated a recently introduced commercial semiautomated latex agglutination test (LAT) kit for pseudorabies antibody. A total of 1,191 swine sera were tested using the new procedure and 3 established tests: the manual LAT, the serum neutralization test (SNT), and an enzyme-linked immunosorbent assay (ELISA). There was close agreement among results of semiautomated LAT, the manual LAT, and ELISA but less agreement between semiautomated LAT and SNT. Overall, the sensitivities of the 4 tests were as follows: semiautomated LAT = manual LAT > ELISA > SNT. For 74 samples of known pseudorabies antibody status, the overall specificities were as follows: semi-automated LAT = manual LAT = SNT > ELISA. Because of its relative insensitivity, the SNT should no longer be considered the official "gold" standard for pseudorabies testing in the on-going eradication program. However, because no single test was perfect for all samples, a scheme including 3 tests in the following sequence is recommended: 1) screening using semiautomated LAT or ELISA and 2) confirmation testing of positives by manual LAT and SNT, with any sample that tests positive by any 2 tests being regarded as true positive. Pseudorabies is caused by the pseudorabies virusRecently, the same principle used in the manual LAT (PRV), 4 an alphaherpesvirus, and is an economically (i.e., agglutination of PRV antigen-coated latex partiimportant viral infection of swine in the United States cles in the presence of specific PRV antibody) was and many other countries. The economic impact of applied to the development of a semiautomated latex pseudorabies on the US swine industry is estimated to agglutination assay. b In the study described here, we be $21 million per year (Hallam JA et al., unpublished evaluated the ability of the semiautomated LAT to data). Swine constitute the main host and natural res-detect PRV antibody in field sera submitted for PRV ervoir of PRV. Pigs can become latently infected and diagnosis and in negative and positive control laboperiodically shed infectious virus particles into the en-ratory sera. The semiautomated LAT results were vironment; other species such as cattle, sheep, goats, compared with results from 3 other PRV antibody tests dogs, and cats that are susceptible to PRV usually ac-(manual LAT, ELISA, SNT) using the same sera. All quire a lethal infection and are therefore dead-end 4 tests are approved by the USDA for official pseuhosts. 4 dorabies testing. Strategies adopted for the control of pseudorabies rely on the knowledge that any pig that has contracted Materials and methods a primary infection can become latently infected and Serum samples. The 1,191 serum samples tested (Tables must therefore be considered a potential source of 1, 2) included 1,117 samples randomly selected from field transmission of infectious virus. Working on that sera submitted to...

The Development of a Semi‐automated Latex Agglutination Test for the Detection of Antibodies toAnaplasma marginaleUsing a Cell Culture‐derived Antigen

“…B. bouis ) and pseudorabies virus. 9‐12 The LAT for Chlamydia psittaci has been shown to detect both IgM and IgG antibodies. 9 The LAT offers a rapid and reliable test for diagnosis of diseases that previously required lengthy and complicated tests.…”

“…9 The LAT offers a rapid and reliable test for diagnosis of diseases that previously required lengthy and complicated tests. 11…”

Development of a Latex Agglutination Test Using The Major Epitope Domain of Glycoprotein E of Pseudorabies Virus Expressed in E. coli to Differentiate Between Immune Responses in Pigs Naturally Infected or Vaccinated with Pseudorabies Virus

“…Thus, the latex agglutination test (LAT) is an economic and low-technology alternative to ELISAs. Several PRV-LATs for the detection of antibodies to PRV in pigs have been developed and evaluated (Schoenbaum et al, 1990;Rodgers et al, 1996), but no report has been published describing a LAT for the detection of antibodies to the glycoprotein E of PRV in pigs. This report describes a gE latex agglutination test (gE-LAT) that uses the major epitope domain of gE of PRV as antigen bound to latex beads to detect antibodies to gE in wild-type but not in vaccinated pigs.…”