Minor capsid protein involved in virus transmission by the vector Polymyxa. Associated with one extremity of viral particles. This protein is translated as a fusion protein by episodic readthrough of the termination codon at the end of the capsid protein. Readthrough of the terminator codon TAG occurs between the codons for Ala-176 and Gln-178, thereby producing the 91 kDa readthrough protein. Belongs to the virgaviridae capsid protein family.