EPIDEMIOLOGY AND DEVELOPMENT OF RECOMBINANT ANTIGEN BASED DIAGNOSTICS FOR BOVINE LEPTOSPIROSIS
Loading...
Date
2022
Authors
Journal Title
Journal ISSN
Volume Title
Publisher
KARNATAKA VETERINARY, ANIMAL AND FISHERIES SCIENCES UNIVERSITY, BIDAR
Abstract
The present study was aimed to study seroepidemiology of leptospirosis and to
express the leptospiral surface adhesion (rLsa 44) protein of pathogenic Leptospira
interrogans serovar Pomona in E. coli and its evaluation as a potential diagnostic antigen.
The observed seroprevalence of bovine leptospirosis at animal level and farm level in
Telangana state was 41.36 per cent and 77.61 per cent respectively. The highest
seropositivity (80.95%) was observed in Wanaparthy and Rangareddy and the lowest
seropositivity (20%) was observed in Mancheriala district. The prevalent leptospiral
antibodies were predominantly against the serogroups Icterohemorrahgiae (32.4%),
Pomona (22.16%), Javanica (19.07%), Australis (17.01%), Bataviae (15.46%), Bankinang
(12.89%), Hebdomadis (12.89%). Further, the breed of the animal (p=0.03) and the health
status of the animal (p=0.03) are the significant risk factors associated with the prevalence
of leptospirosis. Furthermore, multivariate statistical analysis of farm factors revealed that
the size of the farm (p=0.05), presence of the dog in and around the farm (p=0.039),
presence of rodents in the farm (p=0.011), farms using fodder from wet soils (p=0.043) and
farms closer to the water bodies (p=0.041) were significantly associated with the
prevalence of bovine leptospirosis. Leptospiral surface adhesion (Lsa 44) gene was
amplified employing designed primers by polymerase chain reaction and the purified
amplicon was initially cloned in pGEM-T Easy vector in a pET vector expression in E.
coli. The expressed recombinant protein after induction with IPTG was purified through
Ni-NTA column and characterized by SDS-PAGE and western blot, which confirmed the
expressed reactive protein is Leptospira specific with a molecular weight of ~44 kDa. The
antigen was coated on latex beads and assessed for its suitability as diagnostic antigen in
latex agglutination Test (LAT) for the development of new diagnostics. Further, the
evaluation of rLsa 44 LAT beads revealed a relative diagnostic sensitivity and diagnostic
specificity of 93.55 per cent and 90.62 per cent respectively with an accuracy of 92.06 per
cent against MAT while testing known MAT positive and negative bovine sera samples
(n=126) collected from cattle and buffaloes associated with the reproductive problems.
This rLsa 44 LAT is an extremely simple and rapid test and can be used as a diagnostic
tool at the field level. This study appears to be the first to assess the prevalence of bovine
leptospirosis at the farm level in endemic conditions and to use rLsa 44 protein for the
detection of anti-leptospiral antibodies in cattle and buffaloes as a preliminary screening
test.