Development and evaluation of a double antigen sandwich Enzyme-Linked Immunosorbent Assay to identify A. marginale-infected and A. centrale-vaccinated cattle.

SARLI, MACARENA; THOMPSON, CAROLINA S.; NOVOA, MARÍA B.; VALENTINI, BEATRIZ S.; MASTROPAOLO, MARIANO; ECHAIDE, IGNACIO E; S.TORIONI DE ECHAIDE, SUSANA M; PRIMO, MARÍA E.

JOURNAL OF VETERINARY DIAGNOSTIC INVESTIGATION

AMER ASSOC VETERINARY LABORATORY DIAGNOSTICIANS INC

Año: 2019

1040-6387

Bovine anaplasmosis is a worldwide infectious disease caused by the intraerythrocytic rickettsia Anaplasma marginale, transmitted by ticks and fomites. A. centrale is a less virulent subspecies used as live vaccine in cohorts of 8- to10-month-old calves that did not naturally reach enzootic stability. Three variants of a double antigen sandwich ELISA (dasELISA) based on the recombinant major surface protein 5 of A. marginale (dasELISAm), A. centrale (dasELISAc), and both together (dasELISAmc) were developed to detect antibodies against Anaplasma spp. These tests were validated using serum samples from 388 bovines not infected with Anaplasma spp., 436 from bovines infected with A. marginale and 358 with A. centrale, defined by nPCR. A total of 462 samples were compared with a competitive commercial ELISA. Specificity for the 3 dasELISA variants was higher than 97% and global sensitivity was 92.6%, 85.7% and 97.4% for dasELISAm, dasELISAc and dasELISAmc, respectively. Sensitivity ranged from 97.7% to 86.3% for dasELISAm and from 77.7% to 95.5% for dasELISAc for A. marginale-infected or A. centrale-vaccinated bovines, respectively. Sensitivity of dasELISAmc was similar for both groups (>96%). The agreement rate between dasELISAmc and cELISA was 96.3% (k=0.92); the former test allowed earlier detection of seroconversion of vaccinated cattle than cELISA. Based on these results, the test could be used to a) determine the enzootic stability/instability of anaplasmosis in calves b) conduct epidemiological studies, and c) evaluate the infectivity of A. centrale live vaccine. dasELISAmc could also be used to conduct epidemiological studies in other animal species, after a validation procedure.