Lumpy skin disease (LSD) is a highly infectious viral disease of cattle caused by LSD virus (LSDV), which was first reported in Armenia in late 2015. It was identified in pasture-raised cattle near the border with Iran. Currently, vaccination plays a key role in preventing further incursion of disease in high-risk areas. The purpose of this work was to assess the quality of vaccination currently used in Armenia by determining the immune response of the heterologous dry culture sheep pox virus-based vaccine against LSD in cattle. Seroprevalence and seroconversion testing was carried out using an ELISA to detect specific antibodies against LSD before and 30 days after vaccination in three adjacent regions of Armenia (Ararat, Armavir, Gegharkunik). Ixodes ticks were also examined for the presence of LSDV via real-time PCR. We found that the heterologous vaccine used in Armenia creates a high level of population immunity of 86.09% (83.83–87.97%) and no adverse side effects were observed in cattle. Of the 6 types of Ixodes ticks identified and tested, we found no evidence of LSDV circulating in these vectors. These results suggest that regular serological monitoring via ELISA and heterologous vaccination should continue in areas of Armenia at high risk for incursion of LSD to reduce the spread of this highly infectious transboundary disease.

The transmission of lumpy skin disease (LSD) occurs through ticks, mosquitoes, and flies. The most effective way to combat LSD is to conduct large-scale vaccination, covering the entire cattle population with safe and effective vaccines, while introducing restrictions on the movement of livestock. The first and only LSD cases that occurred in Armenia happened in 2015,and they were controlled with the use of a once yearly heterologous sheep pox vaccine for cattle in high-risk areas. We have previously reported on the safety and immunogenicity of this vaccine in cattle, but information on the duration of immunity is lacking. Our aim was to determine the duration of immunity to the LSD virus (LSDV) in cattle when utilizing a heterologous sheep pox vaccine. We have evaluated antibodies in cattle blood prior to and post-vaccination (1, 6, and 11 months). We have utilized an enzyme-linked immunosorbent assay to follow the development and waning of LSDV antibodies in vaccinated cattle in two age groups: 1) young unvaccinated cattle ≤12 months of age and 2) adult cattle that had previously been vaccinated. Our results were consistent with our previous study in Armenia, showing a high level of population immunity, 80.0–83.3%, in both age groups at 1 month, with a significant (p = 0.001) drop for young cattle at 6 months. Previously vaccinated adult cattle showed a longer duration of immunity at 11 months for this heterologous sheep pox vaccine. Based on these data, we advise that young cattle receive an additional booster vaccination 4–6 months after their first vaccination, and then yearly vaccinations in high-risk areas.