Lumpy skin disease (LSD) of cattle, caused by the lumpy skin disease virus (LSDV), results in significant economic losses and restricted cross-border livestock trade. Although live attenuated vaccines are commercially available, the inactivated vaccines would be an appropriate substitute because they are devoid of any adverse reaction and cannot mutate to produce new viral strains. The objectives of this study were to develop an inactivated oil-adjuvanted vaccine using a local isolate of LSDV and to evaluate the immune response of this vaccine in rabbits. The LSDV was isolated from scab samples of suspected cows by inoculating embryonated chicken eggs via the chorioallantoic membrane route. One of the isolates was adapted to grow in Madin-Darby bovine kidney cells, followed by its inactivation with binary ethyleneimine. Montanide ISA50 V2 was added as an adjuvant. A total of 24 rabbits were divided into three groups of eight each; Group A received our inactivated vaccine while Group B was given a commercial live vaccine. Group C served as a non-vaccinated control. The mean antibody titers were statistically analyzed by Dunnett’s test. The D-value of 77.78 indicated that the vaccine produced protective antibodies.

Background and Aim: Lumpy skin disease (LSD), caused by the LSD virus (LSDV), results in severe economic losses, reduced productivity, and restricted livestock trade. Although live attenuated vaccines are available, they pose risks such as viral shedding, recombination, and reversion to virulence. Inactivated vaccines, being safer alternatives, are particularly suitable for disease-free regions. This study aimed to develop an inactivated oil-adjuvanted vaccine using a local LSDV isolate and evaluate its immunogenicity and protective efficacy in rabbits. Materials and Methods: Scab samples were collected from clinically suspected LSD cases, and LSDV was isolated through the chorioallantoic membrane route in embryonated chicken eggs. The virus was adapted to Madin-Darby bovine kidney (MDBK) cells, inactivated with binary ethyleneimine, and formulated with Montanide Immune System Activator 50 V2 adju­vant. Sterility and safety were evaluated in laboratory animals. Twenty-four rabbits were divided into three groups: Group A received the experimental inactivated vaccine intramuscularly, Group B received a commercial live attenuated vaccine sub­cutaneously, and Group C served as controls. Antibody responses were assessed using enzyme-linked immunosorbent assay (ELISA) and virus neutralization tests. A challenge study with a virulent local LSDV strain was conducted to evaluate protec­tive efficacy. Results: The inactivated vaccine elicited robust antibody responses, with ELISA sample-to-positive ratios increasing from 4.3% at baseline to 166.6% on day 42, compared with 210.1% in the live vaccine group and 6% in controls. Neutralizing antibody titers ranged from 1:32 to 1:128 (mean 1:80) in the inactivated group, compared with 1:32–1:256 (mean 1:148) in the live vaccine group, both surpassing the protective threshold (≥1:16). Post-challenge, the inactivated vaccine conferred 86% vaccine efficacy, with only mild clinical signs observed in one rabbit, while the control group developed typical LSD symptoms. No adverse reactions were recorded in vaccinated animals. Conclusion: The experimental inactivated oil-adjuvanted vaccine induced strong protective immunity in rabbits, compara­ble to the live attenuated vaccine but with an improved safety profile. Its inability to revert to virulence or transmit between animals makes it a promising candidate for large-scale use, especially in regions aiming to maintain disease-free status. Further evaluation in cattle under field conditions is warranted to confirm its long-term protective efficacy and potential for inclusion in control strategies. Keywords: Capripoxvirus, immunogenicity, inactivated vaccine, lumpy skin disease, Montanide ISA 50 V2, rabbit model.