No, no, Faldage suggested that it might be one of the class of Latin nouns which don't take a plural. There's no proof that this is the case, and the Notre Dame dictionary entry suggests that, in fact, it does take a plural and conforms to the regular Latin second declension noun formation rules.

Jenet is suggesting that s/he thinks it's a neuter noun. I'm saying that I don't think it is. I think it's either masculine (most likely if it's second declension) or feminine, but NOT neuter. Since my "big-as-a-house" Latin dictionary is packed away, I can't look it up so I'm not getting dogmatic about it.

Virus, in its Latin sense, has absolutely nothing to do with viruses in English, although the English word comes from the Latin root. It means "poisoned water" or "tainted water" in Latin. You know, what happened when the Federal soldiers threw dead animals down Confederate wells in the 1860s, that kind of thing, presumably. More e.coli than ebola, if you see what I mean!