RESUMO
This cross-sectional study was conducted to estimate seroprevalence and to identify flock-level factors associated with seropositivity to brucellosis in small ruminants in Kerman province, southeastern Iran. In October-November 2011, serum samples were randomly collected from 1767 sheep and 1233 goats, older than 18 months, from 300 flocks. The sera were initially screened for the presence of anti-Brucella antibodies using the Rose-Bengal test; those found to be positive were then examined by Wright and 2-mercaptoethanol Brucella agglutination tests. A questionnaire was used to collect data on flock-level factors likely associated with the within flock seroprevalence of brucellosis. The associations were statistically evaluated for significance in multivariable logistic models. Sixty three flocks (21.00%; 95% CI: 16.80-26.60) had at least one seropositive animal. The mean within-flock seroprevalence was 3.10% (95% CI: 2.60-3.90). The presence of newly purchased animals (OR=3.42; 95% CI: 1.35-8.65) was significantly associated with seropositivity. Our findings highlight the role of animal movement among flocks in the epidemiology of brucellosis in this region. Thus, a control program for brucellosis in the region is suggested to impose appropriate restrictions on animal trade and improve knowledge of livestock owners about quarantine principles for newly purchased animals.
RESUMO
Recombinant antibodies have been proposed as invaluable tools for various therapeutic and diagnostic purposes. Here, we describe the development of a novel latex agglutination test (LAT) using single-chain Fv recombinant antibody fragment for the detection of K99(+) enterotoxigenic Escherichia coli strains. For the production of a single-chain Fv antibody fragment (scFv) against the major colonization factor (FanC) of K99 antigen, the scFv gene was integrated into a bacterial expression vector under the control of T7 promoter. After high-level expression of soluble scFv (approximately 50 mg/l) in flask cultivation of E. coli DE3 and purification, scFv was immobilized on different latex particles, and then, these sensitized beads were used in LAT. Results obtained with our latex reagents revealed that the recombinant antibody-coated particles were able to give a good agglutination signal with purified antigen, intact cells displaying this protein and clinical specimens. The strength of agglutination of scFv-coated beads for antigen was comparable to that of polyclonal anti-K99-coated particles. However, the assay proved to be simple and rapid, similar to conventional LATs, and owing to more convenient and economical production of recombinant antibodies, they can be considered as a useful reagent for replacing monoclonal antibodies in LATs.
