Emergence of Lineage E.4 and Structural Plasticity of A28L Protein in Mpox Virus: Characterization of LCR7 Length Polymorphisms Across Lineages — Shenzhen City, Guangdong Province, China, 2023–2025
What is already known about this topic? The A28L protein is involved in mpox virus (MPXV) attachment and fusion, is a major target of neutralizing antibodies, and contains regions prone to genetic variation. What is added by this report? Analysis of 6,834 global and 260 Shenzhen MPXV genomes identified lineage-specific length polymorphisms in the A28L low-complexity region (LCR7). Emerging E.4 viruses exhibited complex deletion patterns and a characteristic OPG153_E293Q substitution, indicating ongoing structural diversification. What are the implications for public health practice? Structural variation in A28L provides additional insight into MPXV evolution beyond conventional single-nucleotide analyses. Continued surveillance of these genomic features may improve monitoring of viral transmission and the emergence of new variants.