Abstract
Background:
In 2021, Vietnam experienced an outbreak of Lumpy skin disease (LSD), which infected 207,687 cattle and buffaloes, as officially reported, and resulted in the culling of 29,182 animals.
Aim:
In this study, samples from cattle that died and showed typical signs of LSD in the Ha Tinh province of Vietnam were confirmed by three WOAH-recommended methods and further studied to compare the Vietnam and China reference strains to the new clinical cases.
Methods:
Three methods recommended by WOAH for agent detection (PCR, virus isolation, and transmission electron microscopy) were used to confirm this clinical LSD case. The sequence analysis of three well-known markers (P32, RPO30, and GPCR genes) has been utilised in Vietnam to understand this circulating pathogen better.
Results:
Our findings showed that the CX01 LSDV strain is 100% identical to the Vietnam reference strain HL01 and China reference strains based on P32 and RPO30 genes. Interestingly, analysis of the nucleotide sequence of the GPCR gene showed that the CX01 strain belongs to the same cluster as the reference strains, but it has branches different from those of both the HL01 and China LSDV strains. The nucleotide identification between the CX01 strain and these reference virus strains ranked 99.65 – 99.91%, suggesting that it is a new variant of LSDV.
Conclusion:
This finding is new and indicates that at least two variants of the LSD virus were circulating in Vietnam based on analysis of the GPCR gene. Additionally, these results suggest that the sequence analysis of the GPCR gene is a great tool for subgrouping LSDV circulating in Vietnam.

Key words: Lumpy skin disease, MDBK, Diagnosis, GPCR, Vaccine