ABSTRACT
The present study reports the detection and molecular characterisation of rotavirus C (RVC) in sloth bears (Melursus ursinus) rescued from urban areas in India. Based on an RVC VP6 gene-targeted diagnostic RT-PCR assay, 48.3% (42/87) of sloth bears tested positive for RVC infection. The VP6, VP7, and NSP4 genes of three sloth bear RVC isolates (UP-SB19, 21, and 37) were further analysed. The VP6 genes of RVC UP-SB21 and 37 isolates were only 37% identical. The sequence identity, TM-score from structure alignment, and selection pressure (dN/dS) of VP6 UP-SB37 with pig and human RVCs isolates were (99.67%, 0.97, and 1.718) and (99.01%, 0.93, and 0.0340), respectively. However, VP6 UP-SB21 has an identity, TM-score, and dN/dS of (84.38%, 1.0, and 0.0648) and (99.63%, 1.0, and 3.7696) with human and pig RVC isolates, respectively. The VP7 genes from UP-SB19 and 37 RVC isolates were 79.98% identical and shared identity, TM-score, and dN/dS of 88.4%, 0.76, and 5.3210, along with 77.98%, 0.77, and 4.7483 with pig and human RVC isolates, respectively. The NSP4 gene of UP-SB37 RVC isolates has an identity, TM-score, and dN/dS of 98.95%, 0.76, and 0.2907, along with 83.12%, 0.34, and 0.2133 with pig and human RVC isolates, respectively. Phylogenetic analysis of the nucleotide sequences of the sloth bear RVC isolates assigned the isolate UP-SB37 to genotype G12, I2 for RVC structural genes VP7 and VP6, and E1 for NSP4 genes, respectively, while isolates UP-SB19 and UP-SB21 were classified as genotype G13 and GI7 based on the structural gene VP7, respectively. The study suggests that the RVCs circulating in the Indian sloth bear population are highly divergent and might have originated from pigs or humans, and further investigation focusing on the whole genome sequencing of the sloth bear RVC isolate may shed light on the virus origin and evolution.
ABSTRACT
Leptospirosis is an exacerbating factor responsible for the drastic decline of sloth bear population in India. In this study, a multipronged approach based on antigen detection using Polymerase Chain Reaction (PCR) employing G1/G2 and LigBF/LigBR primers, antibody detection using Microscopic Agglutination Test (MAT) and recombinant LigBCon1-5 antigen based Latex Agglutination Test (rLigBCon1-5 LAT), serum biochemistry using hepatic (serum glutamate oxalo acetic transaminase (SGOT) and serum glutamate pyruvic transaminase (SGPT) and renal biomarkers (blood urea nitrogen (BUN) and Creatinine) and gross/histopathological evidence in liver and kidneys were employed to investigate leptospirosis in captive sloth bears. A total of 133 serum samples collected from Agra (n=113) and Bannerghatta (n=20) sloth bear rescue centers were screened using MAT and rLigBCon1-5 LAT. A total of 87 and 78 sera tested positive by MAT and LAT respectively. Pyrogenes was the leading serovar obtained using MAT followed by Icterohaemorrhagiae, Javanica, Grippotyphosa, Canicola and Tarassovi. The relative sensitivity, specificity and accuracy of rLigBCon1-5 LAT in comparison to MAT were 89.66%, 100% and 93.23% respectively. PCR performed on hepatic and renal tissues showed amplicon of 285 and 219 base pairs for G1/G2 and LigBF/LigBR primers respectively. Gross evidence (icteric liver, severely engorged hepatic sinusoids, congested kidneys with necrotic white spots on sub capsular surface), histopathology (severe hepatic degeneration and tubulointerstitial nephritis) and elevated hepatic/renal biomarkers were suggestive of leptospirosis. This study suggests that rLigBCon1-5 LAT can be employed as a pen-side test for detecting leptospirosis in sloth bears.
