Neuter nouns of the second declension don't generally have plurals that end in -i, but rather in -a, so "vira" would be equally possible. It's also important t

Neuter nouns of the second declension don't generally have plurals that end in -i, but rather in -a, so "vira" would be equally possible. It's also important to note that scholars don't actually know the proper plural of virus because they haven't really found one in extant literature. Wikipedia has a longer discussion at http://en.wikipedia.org/wiki/Plural_of_virus#Virus http://en.wikipedia.org/wiki/Plural_of_virus#Virus