ASSESSMENT OF IMMUNOGENICITY OF LIVE ATTENUATED GOATPOX VACCINE AGAINST LUMPY SKIN DISEASE IN CATTLE
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Date
2024-03
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SRI VENKATESWARA VETERINARY UNIVERSITY, TIRUPATI - 517 502. (A.P.) INDIA
Abstract
Lumpy skin disease (LSD) is a rapidly emerging, transboundary and notifiable
disease listed by the World Organization for Animal Health. LSD is being reported
regularly with escalated incidence in India ever since its first appearance in 2019. Severe
systemic disease is reported in the affected cattle, resulting in devastating economic
losses. Mass vaccination of susceptible animals is the foremost approach in tackling
infectious diseases. However, several heterologous and homologous vaccines are being
used as a prophylactic measure across the globe to control LSD outbreaks. Although the
efficacy and immunogenicity of homologous LSD vaccines is known to be excellent, cost
of vaccine production along with the Neethling responses observed in the vaccinated
animals urged the need for alternative vaccine candidates. Owing to its high degree of co
linearity and amino acid identity of LSDV with other Capripoxviruses (CaPVs),
heterologous vaccines employing Goatpox vaccines (GPV) and Sheeppox vaccines
(SPV) can be safely used to protect against LSDV.
The present study deals with an objective to determine the optimum dose of
Goatpox vaccine against LSD infections in cattle. A total of 31 samples were collected
from clinical cases suspected for LSD, in different areas of Andhra Pradesh during
September to December, 2022. Of the 31 samples, 26 were found positive for LSDV by
PCR using primers targeting CaPV- specific P32 gene and LSDV- specific RPO30 gene.
Clinical samples (n=10) confirmed by PCR were considered for isolation of LSDV in
Madin-Darby Bovine Kidney (MDBK) cell line. LSDV (LSDV/Cattle/VJA
PNGR/SVVU/2022) could be isolated from two samples (nasal swab and skin scab, both
collected from a single clinical case) in the fifth passage showing characteristic cytopathic
changes. MDBK amplified virus was adapted to Vero cell line and obtained infectivity
titer of 10-7.595 per 100 μL is further employed for use in serum neutralization test.
Phylogenetic analysis of the LSDV isolate based on full length ORF036 gene (RPO30)
showed 100 % identity and formed a distinct clade with Middle-east Asia and African
isolates. Amino acid specific signatures to differentiate CaPVs were noticed and estimates
of evolutionary divergence over sequence pairs between clusters was determined that
showed a distance of 9.52 % between vaccine strains and the field isolate in the present
study.
Vaccination trial was conducted in randomly selected heifers placed into four
groups (A, B, C and D) of eight animals each. Group A served as control group, while
groups B, C and D were vaccinated with 1mL, 2mL and 3mL of 1 X 103.0 TCID50/dose
of Goatpox vaccine respectively. Group D vaccinated with 3 times the dose used in goats
produced the best humoral immunity that was persistent till the end of the trial i.e., 35
days post vaccination(p<0.05). Thus, this study shows thrice the dose of Goatpox vaccine
used in goats is considered as the optimum dose in cattle against LSD.