Detection of bovine leukemia virus specific antibodies using recombinant p24-ELISA.
We developed an indirect ELISA test (rp24-ELISA) for the detection of antibodies against the p24 capsid protein of bovine leukemia virus (BLV) in bovine serum samples. A recombinant p24 (rp24) was expressed in the Escherichia coli expression system, purified in a nickel charged resin and used as antigen in the ELISA test. A cut-off point was established considering the distribution of reactivity values obtained by rp24-ELISA on a set of 555 field serum samples that were stated as double positive (DP) or double negative (DN) by the combination of commercial agar gel immunodiffusion (AGID) assay and gp51-ELISA tests results. The rp24-ELISA showed good concordance with the agar gel immunodiffusion assay, when 710 serum samples were analyzed. In addition, rp24-ELISA demonstrated to be a precise assay with good repeatability and reproducibility and a better analytical sensitivity than AGID. From 67 discordant rp24-ELISA-AGID sera, 4 negative reactors were from the DP group, 28 positive samples were from the DN group and 35 positive samples were stated as negative by AGID but positive by the gp51-ELISA. Samples from this last subgroup were sent to an OIE reference laboratory where 28 samples were stated as negative, 5 samples were stated as positive and 2 as inconclusive. Complete concordance with blind previous results from an international proficiency test panel confirmed the capability of the assay to discriminate between infected and non-infected animals. In conclusion, the rp24-ELISA developed and standardized demonstrated to have good analytical characteristics to be considered for screening of BLV.
Gutiérrez
G
G
Instituto de Virología, Centro de Investigaciones en Ciencias Veterinarias y Agronómicas, INTA, C.C. 1712, Castelar, Buenos Aires, Argentina. ggutierrez@cnia.inta.gov.ar
Alvarez
I
I
Fondevila
N
N
Politzki
R
R
Lomónaco
M
M
Rodríguez
S
S
Dus Santos
M J
MJ
Trono
K
K
D000818:Animals; D000914:Antibodies, Viral / Q000097:blood*; D002417:Cattle; D003001:Cloning, Molecular; D016583:Enzootic Bovine Leukosis / Q000097:blood / Q000175:diagnosis / Q000276:immunology*; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary*; D004926:Escherichia coli / Q000378:metabolism; D005786:Gene Expression Regulation; D001909:Leukemia Virus, Bovine / Q000276:immunology*; D011994:Recombinant Proteins; D014758:Viral Core Proteins / Q000276:immunology*
D000914:Antibodies, Viral; D011994:Recombinant Proteins; D014758:Viral Core Proteins; C089189:core protein p24, bovine leukemia virus