Orthopoxvirus B5 protein (B5)

The Orthopoxvirus B5 protein is a 42-kDa type I transmembrane glycoprotein essential for the formation and dissemination of the extracellular enveloped virus (EEV) particles (UniProt: P04307). It is highly conserved across the Orthopoxvirus genus, including Variola virus (smallpox) and Monkeypox virus (PubMed: 15140980). The protein consists of an extracellular domain with four short consensus repeats (SCRs), a transmembrane anchor, and a short cytoplasmic tail (PubMed: 11831707). B5 is critical for the wrapping of intracellular mature virus (IMV) particles in host-derived membranes and for the induction of actin tails that propel the virus into adjacent cells (Journal of Virology: 10.1128/JVI.78.15.8038-8048.2004). Because EEV is the form of the virus responsible for long-range spread within the host, B5 is a major target for the host's neutralizing antibody response (NIH: PMC114367). Therapeutic strategies targeting B5 include the use of Vaccinia Immune Globulin (VIG) and the development of specific monoclonal antibodies like c8A and 7D11 to prevent viral spread (PubMed: 17554014). It is also a key antigen in both traditional and next-generation orthopoxvirus vaccines (CDC).

Other names

B5R proteinEnvelope glycoprotein B5Complement control protein homologVaccinia virus B5 protein

Neutralization of the extracellular enveloped virus (EEV) and inhibition of viral egress and actin-mediated cell-to-cell spread.