MOLECULAR CHARACTERIZATION OF LUMPY SKIN DISEASE VIRUS AND EXPRESSION OF MAJOR IMMUNO-DOMINANT PROTEIN/S FOR THEIR DIAGNOSTIC EVALUATION
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Date
2022
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Abstract
Lumpy skin disease is a transboundary poxviral disease of cattle and Asian water buffalo caused by Lumpy Skin Disease virus (LSDV). India reported its first emergence in 2019 from Odisha state followed by spread to several states including Tamil Nadu. The present study was undertaken to gather necessary data regarding the molecular characterization of the field isolates with an aim to develop diagnostics. A total of 108 samples were collected from twelve districts of Tamil Nadu and one village from Karnataka for a period of two years from August 2020 to July 2022 from suspected cases of LSD. Initial screening was done by P32 and F gene based PCRs in which, 93.8 per cent of scabs (n=76) and 7.4% of unclotted blood samples (n=2) were found positive.
Scab tissues (n=10) positive in PCR selected for virus isolation in Embryonated Chicken Eggs (ECE) revealed the characteristic pock lesions on CAM during third and fourth passages. One isolate initially passaged in ECE was isolated using BHK 21 cells showed CPE after 48-60 hpi during the third passage. The harvested isolates were further confirmed by PCR.
Molecular characterization based on P32, F, RPO30 and GPCR genes revealed close proximity of the Indian isolates from the study to other LSDV field isolates reported globally. Whereas the vaccine strains of LSDV clustered separately. Further, though closely related, SPPV and GTPV clustered distantly. The GPCR sequence alignment revealed unique signatures (A11, T12, T34, S99, and P199) to confirm its identity as LSDV. The sequences contained 12 nulceotide insertion (nt94 – 105) and corresponding four amino acid (TILS) (aa 30-33). The obtained isolates were more closely related to Kenyan strains and strains from neighboring countries such as Bangladesh, Myanmar and Nepal. This confirms the common exotic source of LSDV responsible for outbreaks in these countries and the transboundary spread across borders.