Immuno-pathological and Molecular Screening of Rabies Virus in Indian Wild Felids: Unravelling Sylvatic to Urban Spillover

Abstract

Rabies poses a fatal threat to humans, domestic animals, and wildlife, with its transmission often exhibiting a wave-like pattern influenced by host population density. Understanding the dynamics of reservoir hosts is critical to elucidating the spatial distribution and transmission pathways of the virus. Between 2014 and 2017, brain specimens from various wild felids in India - including tigers, lions, leopards, and other species-were screened for rabies. Of the 68 samples examined, one jungle cat (73-P/15) and one leopard (01-CD/16) tested positive, representing 2.94% of the total. The infected leopard had previously exhibited aggressive behavior toward domestic animals, resulting in the deaths of 13 cattle and 2 buffaloes due to neurological complications. To assess potential transmission from wildlife to domestic animals, brain samples from one cow and one bullock-exposed to the infected leopard-were also tested for rabies. The direct fluorescent antibody technique (dFAT) revealed the presence of rabies antigen in brain impression smears, which was further confirmed via RT-PCR. Sequencing of the PCR-amplified N gene fragments demonstrated 100% nucleotide identity among the leopard, cow, and bullock sequences, confirming direct transmission from the leopard to the livestock. Phylogenetic analysis placed these sequences within the Arctic-like 1a clade, clustering with other RABV strains circulating in India. This study underscores the importance of maintaining effective barriers between wildlife, humans, and domestic animals to prevent rabies spillover from sylvatic to urban populations.