Rabies in South Indian Cows: An evidence of Sri Lankan Rabies virus Variant Infection Based on the Analysis of Partial Nucleoprotein Gene

Abstract

Rabies is a highly fatal non-suppurative encephalomyelitis, caused by the Rabies virus. Dogs are the major reservoir of rabies in India and are the source of infection to other domestic animals. In this report, laboratory investigation and molecular characterization of isolates from two cows with paralytic rabies is described. Necropsy brain samples from the two cows were tested for the presence of rabies antigen using a fluorescent antibody test and the results were confirmed using RT-PCR. Rabies virus was successfully isolated from both the brain samples in a murine neuroblastoma cell line. The phylogenetic analysis of partial nucleoprotein gene sequences of these isolates showed them to be of a variant of Rabies virus which is closely related to the Sri Lankan Rabies virus lineage as previously reported. In addition, partial nucleoprotein genes of 19 more Rabies virus isolates from southern India were sequenced and of these 11 isolates were found to be closely related to the Sri Lankan lineage. The deduced amino acid sequences of the partial nucleoprotein of the Indian isolates were 96-99% identical to the Sri Lankan isolates. This investigation re-confirms the previous speculations that the Sri Lankan variant of the virus may still be actively transmitted by animals in India.

Sequencing and sequence analysis of partial nucleoprotein (N) gene and phylogenetic analysis of rabies virus field isolates from Gujarat state, India

“…The present phylogentic analysis showed that our field rabies isolates were of high nucleotide sequence similarity with each other and with earlier reported Indian sequences by falling into one cluster that confirms that our field rabies isolates belongs to genotype 1 [16], and because of clustering with other reported Indian isolates which are of Arctic like lineage, our isolates also belong to Arctic like lineage. This endorses the findings of Mehta et al [13], Pant et al [17], Jamil et al [8], Reddy et al [18], Arvindhbabu et al [2] and Nagrajan et al [16].…”

“…Reddy et al [18] found that 30 rabies virus isolates from different states of India were genetically closely related with a single cluster under Arctic/Arctic-like viruses. Arvindhbabu et al [2] found that two adult cow isolates belonged to the genetic cluster 3 (GC3) which is restricted to southern India and GC3 was found to be related to Sri Lankan rabies isolates with a strong bootstrap value of 96%. Nagrajan et al [16] showed that RV isolates in Southern India belong to genotype 1 by phylogenetic analysis of the portion of nucleoprotein gene sequence of 22 rabies virus isolates obtained from domestic animals in Southern India.…”

Natural Rabies Infection in a Domestic Fowl (Gallus domesticus): A Report from India

“…Earlier reports had speculated the presence of this distinct Sri Lankan variant in India and suggested that movement of humans and their animals between Sri Lanka and India, particularly within the southeastern coastal area of the mainland, may have resulted in the movement of this variant between these geographically separate regions [ 13 – 15 ]. Other studies confirmed the circulation of this distinct variant found only in Sri Lanka and mostly the southern part of India [ 16 ]. However, recently isolates from Nepal have also been reported to be phylogenetically related to these distinct variants and this lineage has been designated as the Indian subcontinent rabies virus clade [ 17 ].…”