Evaluation of Humoral Immune Response of Cattle Before and After Vaccination against Lumpy Skin Disease in Ada’a District, Central Oromia, Ethiopia
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2020-09
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Abstract
Lumpy Skin disease (LSD) is an economically important viral disease of cattle affecting all ages and breeds that can be prevented by vaccination in endemic regions including Ethiopia. However, different disease outbreaks in vaccinated cattle raise a question on vaccine efficacy that needs a huge attention to look in to it. To understand why vaccinated cattle experience LSD; longitudinal study coupled with semi-structured interview was employed in Central Ethiopia from October 2019 to June 2020. Semi-structured interview of 30 household was employed to determine knowledge related to LSD and related issues. From these households, 36.67% identified LSD signs and from these households that have knowledge of LSD signs; 16.67% and 3.33% morbidity and mortality was recorded at herd level. The other study of longitudinal approach with 399 sera collected from 113 cattle showed lower proportion of protective antibody level (cut-off value of log titer ≥ 1.5) on pre-vaccination (7.08%) than post-vaccination (8.85% to 41.67% from 7 to 30 days post-vaccination (dpv) sampling. This is logical as immune system need time to build detectable amount of antibody after vaccination. In most of post-vaccination sampling, highest proportion was recorded on 30 dpv. This include, extensively managed (64% at 30dpv), local breed (64%) cows (52%) with the age of ≥ 5 years that could relate with a better immune system development as compared to their counterpart. However, there was no statistical association between those risk factors and their protective antibody appearance. Nonetheless, in both sampling (pre and post-vaccination except day 30th), significant proportions of cattle did not show LSD-specific protective antibody though this does not necessarily mean those cattle were not developed immunity taking cellular immunity in to account. In conclusion, the study showed less number of cattle owner with the awareness of LSD signs and vaccination. Additionally, serum neutralization technique (SNT) result showed a varied level of antibody status with overall less antibody detections that pose a question on a current LSD-vaccine efficacy. To this effect, further field challenge of circulating field strains should be done on vaccinated cattle and assessment of cellular immune response could also play its role to correlate it with vaccine protection level. Additionally, local isolates from outbreaks in the country could be compared with the vaccine strain and used for vaccine production.
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Longitudinal study, LSD, Pre and Post-Vaccination, Protective antibody, Risk factors, Semi-structured interview, SNT, Vaccination