assessment of recombinant a2-latex agglutination test (ra2lat) and ra2-elisa for detection of canine visceral leishmaniasis: a comparative field study with direct agglutination test in northwestern iran

Background: this study aimed to set-up latex agglutination test (lat) and elisa based on recombinant a2 from iranian strain of leishmania (l.) infantum (ra2-ag) and evaluated for detection of anti- leishmania antibodies in dogs compared to standard direct agglutination test (dat). methods: the ra2-ag was synthesized under a part of the a2 gene sequences which contain immune dominant sequences and less number of repetitive sequences. latex beads, 0.8 μm (sigma, usa) were sensitized with ra2-ag. the tests were carried out on sera collected from 350 ownership dogs including symptomatic (n=67), asymptomatic (n=230) canine visceral leishmaniasis (cvl), and (n=53) uninfected domestic dogs as control group. results: anti-leishmanial antibodies were detected in 97 (27.7%), 96 (27.4%) and 29 (%9) of the serum samples by using dat, ra2-elisa, and ra2-latex, respectively with ≥1:320 as a cut-off titer when dat-confirmed cases were compared with the control groups. a combined sensitivity of 52% and specificity of 82.40% for ra2-elisa and 23.8% and specificity 95.38%, respectively were found with ≥1:320 as a cut-off titer when dat-confirmed cases were compared with the control groups. the concordance between ra2-elisa and ra2 latex compared with dat as a gold standard serological test for vl were found 73.7% and 77.5%, respectively. conclusion: a good degree of agreement was found between ra2-elisa and dat (73.7%). ra2-elisa could detect more seropositive serum samples than ra2-lat and it may be recommended as an alternative tool for the diagnosis of cvl.