Application of Monoclonal Antibodies in a Rapid Sandwich Dot-Enzyme Linked Immunosorbent Assay for Identification and Antigen Detection ofLeptospiraSerovars

Development and evaluation of polyclonal antibody-based antigen detection ELISA and dot blot assays as a less costly diagnostic alternative for pathogenic Leptospira infection

Leptospirosis is an infectious, zoonotic disease of worldwide distribution, the cause of which is infection by pathogenic Leptospira. In Chile, dairy cattle are recognized a significant source in the maintenance and transmission of this infection, which causes economic losses and represents an infection threat to workers in the dairy industry. The infection is underestimated in cattle, due to the lack of clinical, pathognomonic signs, as well as the low efficiency of current diagnostic techniques. In this study, we developed antigen ELISA and dot blot assays, based on polyclonal antibodies, to detect pathogenic Leptospira in the urine samples of dairy cattle. The proposed tests showed an acceptable diagnostic accuracy, based on an analytical sensitivity of 1·10⁴ Leptospira per mL for ELISA, and 3.2·10³ for dot blot. These results corresponded with those obtained by qPCR, and the use of urine samples allowed us to propose new diagnostic alternatives for pathogenic Leptospira infection at a low cost, which can provide information on active infection status, which is a key element in control programs both at individual and herd level.

Development and evaluation of monoclonal antibody-based antigen capture enzyme-linked immunosorbent assay for the diagnosis of acute leptospirosis in humans

Monoclonal antibody (MAb)-based ELISA was developed to detect leptospiral antigens from the plasma of febrile patients. The MAb reacts specifically with pathogenic leptospires and the assay possesses excellent diagnostic test parameters compared to PCR, indicating that this new ELISA is useful for the early diagnosis of leptospirosis with low operational cost.

Monoclonal antibodies directed against the outer membrane protein of Bordetella avium

Bordetella avium is the etiologic agent of coryza and rhinotracheitis in poultry. This respiratory disease is responsible for substantial economic losses in the poultry industry. Monoclonal antibodies (MAbs) were produced against the outer membrane proteins (OMPs) of B. avium isolated from diseased chickens. BALB/c mice were immunized with the extracted B. avium OMPs. Then the splenocytes from immunized mice and SP2/0 myeloma cells were fused using PEG 4000. Three stable hybridoma clones (designated as 3G₁₀, 4A₃, and 4E₈) were produced via indirect ELISA and three rounds of subcloning. The MAbs were classified as IgG1, and can recognize the 58  kDa OMP band by Western blot assays. No MAb cross-reactivity with chicken Proteus mirabilis, Escherichia coli, and Salmonella was observed. A double antibody sandwich ELISA (DAS-ELISA) was developed using the rabbit polyclonal antibodies as the capture antibody and MAb 4A₃ as the detection antibody. Under the DAS-ELISA, the minimum detectable concentration of B. avium was 1 × 10(4) CFU/mL, and no cross-reactivity occurred with chicken Proteus mirabilis, Escherichia coli, and Salmonella. Results showed that the DAS-ELISA has good sensitivity and specificity. Clinical application showed the DAS-ELISA was more sensitive than the plate agglutination test. This study may be used to develop a quick and specific diagnostic kit, analyze epitopes, and establish systems for typing B. avium.

Leptospirosis: current situation and trends of specific laboratory tests

Leptospirosis is re-emerging as a worldwide zoonosis and is caused by bacteria of the genus Leptospira. Human leptospirosis is associated with high temperature and humidity. Laboratory tests are indispensible for the early diagnosis and proper disease management. The demand for suitable leptospirosis point-of-care diagnostic tests grows with the awareness and number of incidences. Confirmation is achieved by the microscopic agglutination test, bacterial cultivation, PCR or histopathologic methods. However, high costs, poor standardization and/or elaborate sample preparation prevent routine use at the point of care. Cost-efficient, but insensitive serological methods dominate the diagnostic landscape and, likewise, urgently need improvement toward greater compliance with some of the point-of-care criteria. Combined application of antigen and antibody detection methods increases accuracy, but also new development or transfer of diagnostic technologies should be considered useful. Nano- and microparticle technology may play a key role in improving future antigen detection methods.

Detection and characterization of Leptospira spp. isolated from aborted bovine clinical samples

Leptospira is recognized as an important public health problem worldwide, especially in tropical countries, and is a common cause of abortion in dairy and beef herds. The aim of the present study was to detect and characterize Leptospira as the causative agent of abortion in cattle using a PCR-RFLP in Chaharmahal va Bakhtiari and Isfahan provinces, Iran. A total of 220 bovine aborted foetuses and 120 vaginal discharges from an aborted calf were collected from 64 commercial dairy herds. After isolation of 60 Leptospira spp. from samples, RFLP analysis was carried out with HindIII and HaeIII restriction enzymes in reference strains and isolated for characterization. In a total of 340 specimens, 46 (20.9%) and 14 (11.66%) were identified positive for Leptospira spp. from aborted bovine foetuses and vaginal discharges, respectively. The present results also suggest that L. interrogans serovar hardjo has the highest prevalence in the region under study and L. hardjo is a major pathogen causing bovine abortion in Chaharmahal va Bakhtiari and Isfahan provinces of Iran.