For many years, scientists have used electron microscopy to determine virus capsid structure. Even before modern genetic sequencing tools were developed, EM images helped to distinguish viral morphology, leading to the first attempts at on classifying viruses. Today, electron microscopy still remains an important tool for clinical viral diagnoses and pathogenesis studies, despite electron microscopy being considered "old". However, while electron microscopy is informative in elucidating capsid structure, it isn't able to tell us how capsids are assembled.
A team of researchers has developed a simulation to study viral capsid protein assembly. They use the Cowpea Chlorotic Mottle Virus (CCMV) as their model organism. CCMV's capsid is icosahedral and has an triangulation number of 3, suggesting that CCMV's capsid is made of 180 proteins, each comprised of 190 amino acid residues. They study force-compression curves at different interfaces to investigate breaking events-- events that help them elucidate the probability of an assembly pattern.
From the simulation, they concluded that hexamers do not form at early stages of assembly. They have also determined the amino acid residues that persist most when the capsid is under stress: this will be important for mutation studies, as these locations can be targeted for maximum effect.
Publication linked to news report:
Further reading on electron microscopy uses in the virus field:
-- Sharon Kam
-- Sharon Kam