The ICTV's recommendation for how to write virus, species and other taxa names. (Updated September 16, 2020)
While the ICTV does not officially define abbreviations for virus species, we do provide recommendations fro abbreviating virus names. These abbreviations are provided in the Virus Metadata Resource (VMR): https://ictv.global/vmr/. For the virus, maize streak virus, the suggested abbreviations are MSV/A through MSV/J and MSV/X depending on the virus isolate. The VMR provides GenBank accession numbers linking each virus and abbreviation to the sequence record of the corresponding virus strain. MSV/A is the abbreviation for the exemplar virus (South Africa/A) of the species.