Virology: Structure, Replication, and Veterinary Viruses
What you must know
Build questions around classification (DNA vs. RNA, enveloped vs. non-enveloped, genome polarity), replication strategy (RNA viruses generally replicate in the cytoplasm; most DNA viruses replicate in the nucleus), and consequences of enveloping (enveloped viruses are more fragile, more susceptible to disinfectants and drying, and often transmitted by close contact or vectors). Know the major veterinary families: Paramyxoviridae (distemper, rinderpest), Rhabdoviridae (rabies), Orthomyxoviridae (influenza), Coronaviridae, Parvoviridae (feline panleukopenia, canine parvovirus), Herpesviridae (latency), Retroviridae (reverse transcription, integration), and Poxviridae (large DNA, cytoplasmic replication). Understand antigenic drift (point mutations) versus antigenic shift (reassortment), and latency as a persistence mechanism (herpesviruses).
Traps
Questions test exceptions: Poxviruses are DNA viruses that replicate in the cytoplasm, and retroviruses use reverse transcriptase. Do not assume all RNA viruses mutate rapidly - the point is error-prone polymerases without proofreading. Watch for confusion between non-enveloped viruses (parvovirus, very environmentally stable) and enveloped viruses (fragile). Another trap is equating vaccine type with virus family - modified-live, killed, and subunit vaccines are strategies, not classifications.
Rule of thumb
If the stem emphasizes environmental persistence and resistance to disinfectants, suspect a non-enveloped virus such as parvovirus; if it emphasizes fragility and close-contact spread, suspect an enveloped virus.
Worked example
A question asks which virus is most likely to survive on fomites for weeks and resist many disinfectants. Among parvovirus (non-enveloped) and canine distemper virus (enveloped paramyxovirus), the non-enveloped parvovirus is the answer. The discriminator is envelope status, not host species.