Re-Emergence and Characterization of a Highly Pathogenic Getah Virus on a Pig Farm in Guangdong Province, China

Getah virus (GETV), a mosquito-borne virus capable of infecting multiple economically important animal species, poses a potential epidemic risk. In May 2024, one pig farm from Heyuan, Guangdong Province, China, suffered reproductive disorders in sows and diarrhea in newborn piglets. Out of the six blood samples that were collected, three tested strongly positive for GETV, yielding a positivity rate of 50%. Moreover, a GETV strain (designated GDHYLC2024) was successfully isolated and identified. The viral titer of GDHYLC2024 was 10^7.687 TCID₅₀/mL in Vero cells. Its genome was composed of 11,688 bases in length. Interestingly, compared with GDHYLC23, it had no unique 32-nucleotide repeat insertion in 3' non-coding region. However, phylogenetic analysis showed that GDHYLC2024 and GDHYLC23 clustered in genotype III. Animal infection experiments demonstrated that the GDHYLC2024 strain was highly pathogenic to 4-day-old piglets, which caused obvious clinical symptoms including fever, depression, anorexia, periorbital edema, ataxia, and three deaths out of a total of five individuals in the infection group. This study reported re-emergence of GETV in the same region of Guangdong Province, China. The above findings suggest that GETV continuously poses a threat to farm pig's health and has genetic diversity.