Isolation and Pathogenic Analysis of a Highly Virulent Getah Virus Strain from Henan Province, China

Getah virus (GETV) is a mosquito-borne arbovirus belonging to the genus Alphavirus within the family Togaviridae, which can cause disease in a variety of domestic animals. In recent years, the virus has attracted increasing attention due to its rising prevalence and enhanced pathogenicity. Here, a highly virulent GETV strain was isolated from the intestinal contents of piglets, namely GETV-CH-HNNY-2024 strain. The complete genome sequence length of this strain was 11,690 bp and phylogenetically classified as GIII subtype. Results of the challenge experiment showed that the virus can cause severe diarrhea and 100% mortality in 5-day-old piglets. Further histopathological examination revealed shedding and atrophy of the epithelial villous cells of the jejunoileum, and the piglets had inflammatory infiltration in their lungs. The brain tissue showed lesions of non-purulent encephalitis, with vascular inflammatory cell infiltration. Notably, high viral loads were detected in multiple organs (heart, liver, spleen, lung, kidney, brain, intestine, and lymph nodes)，with peak levels reaching up to 8.93 lg copies/mL (jejunum). Compared with the control group, the infected piglets showed significant impairment of intestinal barrier function and enhanced inflammatory responses. This was evidenced by the downregulated mRNA expression of barrier-related genes (ZO-1 and Occludin) and mucus components (CLCA1, Zg16, and MUC2), the upregulated expression of inflammatory cytokines (IL-6, IL-8, and TNF-α), and increased serum levels of intestinal permeability markers (DAO and D-Lac). Further analysis of the gut microbiota revealed that GETV infection altered the diversity and composition of the cecal microbial community in piglets from the phylum to genus level, which was characterized by a reduction in the abundance of beneficial bacteria (Lactobacillus, Faecalibacterium, Blautia) and an increase in conditional pathogenic bacteria (Escherichia-Shigella, Porphyromonas, Akkermansia). In conclusion, these results contribute to a deeper understanding of GETV pathogenesis and lay the groundwork for developing effective biologics for its control.