They belong to a family called alpha virus. Virulence can be attributed to the glycoproteins, E1 and E2 which also line the shell of the virus. Glycoprotein E1 is responsible for membrane fusion and E2 ( a product of cleavage of p62 by Furin, E3 being the second product) is responsible for receptor recognition. p62 and E1 exist as a precursor before Furin cleaves p62 into E2 and E3.
In a recent Letter to Nature, James E. Voss et al solved the structure of p62-E2 complex as well as E1-E2-E3 complex. This structural insight will help us understand the nature of interaction between the virus and human cells at the level of receptor recognition and membrane fusion following endocytosis.Another interesting aspect is that a change in pH in the endosome transitions the precursor to the mature proteins and subsequently providing virulence.
The X-ray structure of this virus gives valuable insights about the three dimensional structure and therefore epitopes which could be targeted for the development of vaccines against the virus.