Isolation and Characterization of Getah Virus GD2202 from Mosquitoes in Foshan, China

Background: Getah virus (GETV) is a vector-borne virus that can proliferate in mosquitoes and be transmitted to host animals through bites. Clinical infection with the virus mainly causes diarrhea and reproductive disorders in pigs and fever, rash, and edema in horses. This caused huge losses to the pig industry and also affected the level of competition for horses. GETV has proliferated across over 20 regions within China, recently resulting in miscarriages and fatalities among the pig population, Guangdong province. Currently, there are no highly effective preventative or therapeutic strategies for diseases induced by GETV. Understanding the infection pathways, inclusive of GETV transmission vectors, is of paramount importance for the prevention and management of the disease. Results: To clarify the main transmission vectors and genotypes of GETV in this area, 3600 mosquitoes of different species were collected and GETV was detected using quantitative reverse transcription PCR. The minimum infection rate was 1.36 for Culex tritaeniorhynchus and 0.83 for Anopheles sinensis. The GETV GD2202 strain was successfully isolated from C. tritaeniorhynchus using mouse neuroblastoma (N2a) cells, and its complete genome was sequenced by PCR. This represents the first identification and isolation of GETV from mosquitoes in Guangdong Province of Southern China. Comparison with GenBank data showed 99.3% identity with the E2 gene of the GDFS2-2018 and GDFS9-2018 strains causing disease in local pig populations, and a nucleotide similarity of 99.8% with the E2 gene of the HNNY-1, HNPDS-1, and HNPDS-2 strains isolated from pigs in Henan, and the highest identity with the JL1708 strain isolated from mosquitoes in Jilin Province, with a nucleotide similarity in the E2 gene of 99.9%. Phylogenetic analysis showed that it had the closest genetic evolutionary relationship with the Culex-derived JL1708 strain and was on the same evolutionary branch as the pig-derived HNNY-1, HNPDS-1, and HNPDS-2 strains. Conclusion: A comprehensive investigation was undertaken to examine the prevalence of GETV infection among various mosquito species in Foshan, Guangdong Province, China. The findings indicated that C. tritaeniorhynchus acted as the principal vector for transmission, predominantly infected with GETV genotype III. This genotype was consistent with that identified in deceased pig populations and demonstrated significant homology. This study provides a robust scientific basis for understanding the propagation of GETV, thereby offering vital insights for the formulation of disease prevention and control strategies.