SP24, or structural protein of 24kD, is a family of putative virion membrane proteins of plant and insect viruses. These viruses are ssRNA positive-strand viruses, with no DNA stage. The family corresponds to the central region of the ORF3 of insect chroparaviruses and negeviruses and plant cileviruses, higreviruses and blunerviruses. It contains four transmembrane regions. Chronic bee paralysis virus (CBPV) is one of the more common member virions. SP24 is probably one of the major structural components of the virions [1].

1: Powerful sequence similarity search methods and in-depth manual analyses can identify remote homologs in many apparently "orphan" viral proteins. Kuchibhatla DB, Sherman WA, Chung BY, Cook S, Schneider G, Eisenhaber B, Karlin DG; J Virol. 2014;88:10-20. PMID:24155369