Attenuation Profile and Molecular Characterization of a High-Passaged Attenuated Getah Virus Strain

In recent years, the prevalence of epizootic diseases caused by Getah virus (GETV) has surged in China, raising significant concerns for animal health and posing a potential threat to public health. This study aims to systematically compare the phenotypic and genotypic characteristics of a high-passage attenuated GETV strain (HuN1-P230) with its virulent parental strain (HuN1), elucidating the molecular changes associated with the attenuation process. The HuN1-P230 strain exhibited enhanced replication kinetics, higher viral titers, and a small-plaque phenotype in cell cultures compared to HuN1. Notably, pregnant mice inoculated with HuN1-P230 displayed a 100% survival rate among neonates, in stark contrast to the complete absence of live births observed with the parental HuN1 strain, indicating a highly attenuated virulence phenotype. Furthermore, challenge experiments demonstrated that HuN1-P230 conferred complete protection against the virulent HuN1 strain. Genomic comparative analysis revealed that HuN1-P230 harbored 26 nucleotide mutations relative to HuN1, including 11 silent mutations and 15 amino acid substitutions. Structural analysis of the GETV spike protein indicated that the observed antigenic differences were closely linked to amino acid substitutions located on the viral surface. These findings suggest that the phenotypic changes observed during GETV attenuation are closely associated with specific genetic modifications, providing critical insights into the molecular mechanisms underlying viral attenuation and highlighting the potential of HuN1-P230 as a vaccine candidate.