Optimization of In-House Indirect-ELISA & EITB Assays Employing Cysticercus cellulosae Antigens for Serological Detection and PCR Assays for Molecular Detection of Porcine Cysticercosis.

Background: Porcine cysticercosis, caused by metacestodes of Taenia solium is an important neglected zoonosis. We evaluated the presence of anti-cysticercal antibodies and T. solium specific DNA in pig sera and blood samples respectively collected from Maharashtra, India. Methods: A total of three antigens (Scolex Antigen (SA), Membrane Body Antigen (MBA) and Excretory-Secretory Antigen (ESA)) were prepared from metacestodes of T. solium and employed in an in-house developed indirect-IgG ELISA for serological screening of 1000 porcine sera samples at Department of Veterinary Public Health, Nagpur Veterinary College, Maharashtra, India. The ELISA positive sera samples were subjected to EITB Assay for detection of immunodominant peptides. An effort has been made for molecular detection of porcine cysticercosis by PCR assay targeting large subunit rRNA gene of T. solium from blood samples of the corresponding ELISA-positive pigs. Results: The overall seroprevalence of porcine cysticercosis employing SA, MBA and ESA was 12.6%, 8.7% and 12.5% respectively. The lower and medium molecular weight peptides were the most frequently recognised in EITB assay. The numbers of bands recognised in EITB assay were observed to be proportionate with the corresponding ELISA O.D. values. An amplification product of 286 bp was observed in 22.98% (20/87), 30.35% (30/99) and 17.14% (12/70) of the sero-positive samples against SA, ESA and MBA respectively. Conclusion: EITB still remains the gold standard serodiagnosis test for cysticercosis. The inclusion of a greater number of positive samples and purification of antigens may improve the diagnostic efficacy of the tests.

Distribution of Orientia tsutsugamushi in rodents and mites collected from Central India.

Orientia tsutsugamushi, the causative agent of scrub typhus, is an obligate intracytosolic bacterium transmitted among humans and small mammals by some species of larval trombiculid mites (chiggers). It has been recognized as a pathogen of major public health concern in the Asia-Pacific region. As disease is considered as a neglected, there exists a gap in our knowledge of the disease with regard to the sporadic epidemiologic data in endemic areas. The purpose of the study was to find out the vector as well as pathogen distribution in rodents present in the scrub typhus-reported areas in central India. We studied the seasonal variations of occurrence in O. tsutsugamushi in rodents and mites by molecular detection targeting the 56-kDa and 47-kDa genes. Rodent and mite samples were collected during December 2015 to July 2017. A total of 127 samples from rodents, seven pools of mites, and four pools of fleas were collected and processed for DNA isolation. Nested PCRs targeting the 56-kDa and 47-kDa surface antigen genes were performed. In addition, quantification of bacterial load was done by qPCR targeting the 47-kDa gene. During the pre-monsoon season, O. tsutsugamushi was detected in 12% and 10% samples employing the 56-kDa and 47-kDa nested PCRs, respectively, whereas, during post-monsoon season, the respective detection rates were 13.33% and 26.66%. This study predicted a bimodal pattern during the months of pre-monsoon and post-monsoon season with a peak in post-monsoon. Thus, the impact of season on the perpetuation of O. tsutsugamushi in the host was observed.

Prevalence and Phylogenetic Analysis of Orientia tsutsugamushi in Rodents and Mites from Central India.

Orientia tsutsugamushi, the causative agent of scrub typhus in humans, is an obligate intracytosolic bacterium transmitted among animals and to humans by some species of larval trombiculid mites (chiggers) and is hosted mainly by rodents. In this study, we attempted detection of O. tsutsugamushi from blood and tissue samples of rodents trapped from different locations in Central India using PCR targeting the 56 kDa outer membrane protein gene and the 47 kDa high temperature transmembrane protein gene. A total of 59 rodent samples comprising 38 of blood collected from domestic and public surroundings and 21 of tissue from agricultural farm were included in this study. The 56 kDa outer membrane protein gene was detected from 10 of 59 samples by PCR, and the 47 kDa protein gene was detected from 4 of 59 samples by nested-PCR. Mites collected from the rodents were identified as Ornithonyssus bacoti, and one of five pooled samples was found to be positive for O. tsutsugamushi using PCR targeting 56 kDa outer membrane protein gene. Thus, perpetuation of O. tsutsugamushi among rodents and mites was detected constituting a potential public health concern.