Virion associated proteins of equine rhinitis B virus 1 (ERBV1): the non-structural protein 3C(pro) co-purifies with virions.

The study focused on identifying and characterizing the structural proteins of the Equine Rhinitis B Virus 1 (ERBV1), an Erbovirus, and finding that a non-structural protein, 3C(pro), co-purifies with the ERBV1 virions.

Study Focus

In this research, the main focus was on identifying and understanding the structural proteins of a specific genus known as Erbovirus, more precisely Equine Rhinitis B Virus 1 (ERBV1). These proteins, VP1 to VP4, are not yet adequately explored in scientific literature. Furthermore, the study also detailed the purification methods that care specifically used for Cardioviruses.

Methodology

The team employed particular methodologies for virus purification, namely polyethylene glycol and trypsin treatment. While working to discern the organization of ERBV1’s structural proteins, they found the following:

• An unusual observation was that only one of the detected virus proteins, a 26 kDa protein named VP3, had an expected molecular mass. This protein was correctly identified via N-terminal amino acid sequencing.
• Two other proteins, one 56 kDa and the other 29 kDa, were found, but showed unexpected results. These were identified as VP2 and VP1 respectively, but their molecular weights significantly differed from the formerly predicted weights, being 27 kDa larger and 6 kDa smaller respectively.
• When the virus was purified without the use of trypsin, the proteins seemed to have molecular masses more consistent with what was initially predicted for VP1, VP2, and VP3. They were then more accurately identified with antibodies affinity purified to recombinant VP1, VP2, VP3, which were produced in E. coli.

Surprising Results

Interestingly, antibodies affinity purified to a non-structural protein, namely 3C(pro), produced a 27 kDa protein in western blots of the virus, whether it was purified with or without trypsin treatment. This finding suggests that this non-structural 27 kDa protein, 3C(pro), co-purifies with the ERBV1 virions, a previously unknown behavior.