noun
virus
B1
Virus (das Virus, Plural: Viren) refers to a biological pathogen or a computer virus. It's a neuter noun with plural Viren and singular forms like das Virus, dem Virus. No special prepositions; plural uses -en (Viren). The word is regular in declension but has both technical senses.
Examples
Der Gesundheitsminister erklärte, dass die Ärzte gegen das Virus neue Schutzmaßnahmen erprobten, bevor die Lage sich verschlechterte.
The health minister explained that the doctors were testing new protective measures against the virus before the situation worsened.
Das ist ein Virus.
That is a virus.
Der Arzt erklärte, wie das Virus sich verbreitet.
The doctor explained how the virus spreads.
Details
Mnemonics
Imagine a tiny spiky ball labeled 'VIRUS' under a microscope
sounds like English 'virus' — same root
das Virus — think 'das' as neutral for biological terms like 'das Bakterium', 'das Virus'
Notes
Although some speakers may colloquially use 'der Virus', the standard gender is neuter: das Virus. Plural commonly 'Viren'.