Virology Revision Framework
This closing section provides the single classification tool to apply to any virus, mirroring the thirteen-point framework that closed the Bacteriology module. Work through these eleven questions in order for every virus; as with the bacteriology framework, the order reflects genuine logical dependency, each answer constraining and predicting the next.
1. Family: The taxonomic grouping (herpesvirus, picornavirus, flavivirus, orthomyxovirus, and so on, sections 7-10), predicting much of the virus's basic structural and replication biology before any organism-specific fact is known.
2. Genome: DNA or RNA, single or double stranded, and, for RNA viruses, positive or negative sense; the single most fundamental branch point (section 2), directly determining replication location, required enzymology, and whether the isolated genome alone is independently infectious.
3. Envelope status: Present or absent; directly predicts environmental stability, detergent/alcohol sensitivity, and the dominant transmission route (direct contact/droplet/bloodborne for enveloped viruses; faecal-oral/fomite/waterborne for nonenveloped viruses), a genuinely high-yield single fact established in full in section 2.
4. Replication site: Nucleus or cytoplasm, with the specific enzymology required at each site (host DNA polymerase for most dsDNA viruses; virus-supplied RNA-dependent RNA polymerase for RNA viruses; reverse transcriptase plus integrase for retroviruses), section 3.
5. Reservoir: Human-restricted, zoonotic (with the specific animal reservoir), or environmental; directly predicts whether person-to-person transmission is even possible and shapes the entire epidemiological pattern, exactly mirroring the equivalent point in the bacteriology framework.
6. Transmission: The specific route (respiratory droplet, airborne, faecal-oral, sexual, vector-borne, vertical, parenteral, direct contact), following directly from reservoir and envelope status together.
7. Tissue tropism: The specific cell type(s) infected, determined predominantly by host receptor distribution, and, as established repeatedly throughout this module (sections 1, 5, 12, 14), the single strongest predictor of clinical disease pattern of any property in this entire framework.
8. Major disease: The specific clinical syndrome(s), cross-referenced against the syndrome-based organisation of sections 12-16.
9. Persistence or latency: Whether the virus is cleared, causes acute self-limited illness only, establishes true transcriptional latency (herpesviruses), or causes chronic active replication (HBV, HCV) or a combined pattern (HIV), drawing on the full comparative framework of section 18, and directly determining treatment goal (cure versus suppression).
10. Diagnostic method: The specific specimen and test most likely to establish the diagnosis (PCR/RT-PCR, antigen detection, serology with attention to IgM/IgG timing, or, rarely now, culture), drawing on section 20's general principles and each organism's own specific diagnostic window and pitfalls.
11. Prevention: Vaccine availability and mechanism (where one exists), passive immunoprophylaxis (monoclonal antibodies, immunoglobulin), or, where no vaccine exists, the specific behavioural/environmental/vector-control measures relevant given the transmission route established at point 6.
