1.A.135. The African Swine Fever Virus B117L Viroporin (B117L Viroporin) Family
African Swine Fever Virus (ASFV) protein B117L is endowed with low-pH-dependent membrane permeabilizing activity. ASFV is causing a devastating pandemic in domestic and wild swine in Central Europe to East Asia, resulting in economic losses. The virus contains a large double-stranded DNA genome that contains more than 150 genes, most with no experimentally characterized function. Gladue et al. 2023 evaluated the function of the product of gene B117L, a 115-amino-acid integral membrane protein transcribed at late times during the virus replication cycle and showing no homology to any previously published protein. Hydrophobicity distribution of B117L revealed a single TMS. It is an ER protein. Intracellular localization of various B117L constructs also displayed a pattern for the formation of organized smooth ER (OSER) structures compatible with the presence of a single TMS with a cytoplasmic carboxy terminus. Using partially overlapping peptides, the B117L transmembrane helix has the capacity to establish spores and ion channels in membranes at low pH. Evolutionary analyses showed high conservation of the TMS during the evolution of the B117L gene, indicating that the integrity of this domain is preserved. A viroporin-like role for B117L in ASFV entry was suggested.