A viral disease (or viral infection or infectious disease), occurs when an organism's body is invaded by pathogenic viruses, and infectious virus particles (virions) attach to and enter susceptible cells.
Basic structural characteristics, such as genome type, virion shape and replication site, generally share the same features among virus species within the same family.
There are five double-stranded DNA families: three are non enveloped (Adenoviridae, Papillomaviridae and Polyomaviridae) and two are enveloped (Herpesviridae and Poxviridae). All of the non-enveloped families have icosahedral capsids.
There is one family of partly double-stranded DNA viruses: Hepadnaviridae. These viruses are enveloped.
There is one family of single-stranded DNA viruses that infect humans: Parvoviridae. These viruses are non-enveloped.
There are seven positive single-stranded RNA families: three non enveloped (Astroviridae, Caliciviridae and Picornaviridae) and four enveloped (Coronoviridae, Flaviviridae, Retroviridae and Togaviridae). All the non-enveloped families have icosahedral nucleocapsids.
There are six negative single-stranded RNA families: Arenaviridae, Bunyaviridae, Filoviridae, Orthomyxoviridae, Paramyxoviridae and Rhabdoviridae. All are enveloped with helical nucleocapsids.
There is one family with a double-stranded RNA genome: Reoviridae.
There is one additional virus (Hepatitis D virus) which has not yet been assigned to a family but is clearly distinct from the other families infecting humans.
There is one family and one genus of viruses known to infect humans that have not been associated with disease: the family Anelloviridae and the genus Dependovirus. Both of these taxa are non-enveloped single-stranded DNA viruses.
Among the human infecting families there are a number of rules that may assist physicians and medical microbiologists/virologists.
As a general rule, DNA viruses replicate within the nucleus while RNA viruses replicate within the cytoplasm. Exceptions are known to this rule: poxviruses replicate within the cytoplasm and orthomyxoviruses and hepatitis D virus (RNA viruses) replicate within the nucleus.
Four families have segmented genomes: Bunyaviridae, Orthomyxoviridae, Arenaviridae and Reoviridae (acronym BOAR). All are RNA viruses.
Only one family of enveloped viruses causes gastroenteritis (Coronaviridae). All other viruses associated with gastroenteritis are non enveloped.
These are tables of the clinically most important viruses.
The clinical characteristics of viruses may differ substantially among species within the same family:
In 2010 it was reported that the presence of a tobamovirus (Pepper mild mottle virus) in the stool was associated with clinical disease and a specific immune response. If this association can be confirmed it is the first known case of disease caused by a virus previously considered pathogenic only to plants.
Diagnosis and treatment
Viral disease is usually detected by clinical presentation, for instance severe muscle and joint pains preceding fever, or skin rash and swollen lymph glands. Laboratory investigation is not directly effective in detecting viral infections, because they do not themselves increase the white blood cell count. Laboratory investigation may be useful in diagnosing associated bacterial infections, however. Viral infections are commonly of limited duration, so treatment usually consists in reducing the symptoms; antipyretic and analgesic drugs are commonly prescribed.
- Taylor, M.P.; Kobiler, O.; Enquist, L. W. (2012). "Alphaherpesvirus axon-to-cell spread involves limited virion transmission". Proceedings of the National Academy of Sciences. PNAS. 106: 17046–17051. doi:10.1073/pnas.1212926109. PMC 3479527.
- Hunt, M. "Arboviruses". University of South Carolina School of Medicine.
- Fisher, Bruce; Harvey, Richard P.; Champe, Pamela C. (2007). Lippincott's Illustrated Reviews: Microbiology. Lippincott's Illustrated Reviews Series. Hagerstown MD: Lippincott Williams & Wilkins. pp. 354–366. ISBN 0-7817-8215-5.
- Table 1 in: Dimitrov, Dimiter S. (2004). "Virus entry: molecular mechanisms and biomedical applications". Nature Reviews Microbiology. 2 (2): 109–122. doi:10.1038/nrmicro817. ISSN 1740-1526.
- Adams, MJ; Carstens EB (Jul 2012). "Ratification vote on taxonomic proposals to the International Committee on Taxonomy of Viruses (2012)". Arch. Virol. 157 (7): 1411–22. doi:10.1007/s00705-012-1299-6. PMID 22481600.
- Whitley RJ (1996). Baron S; et al., eds. Herpesviruses. in: Baron's Medical Microbiology (4th ed.). Univ of Texas Medical Branch. ISBN 0-9631172-1-1.
- Murray PR, Rosenthal KS, Pfaller MA (2005). Medical Microbiology (5th ed.). Elsevier Mosby. ISBN 978-0-323-03303-9.
- de Villiers EM, Fauquet C, Broker TR, Bernard HU, zur Hausen H (2004). "Classification of papillomaviruses". Virology. 324 (1): 17–27. doi:10.1016/j.virol.2004.03.033. PMID 15183049.
- Blaine T. Smith; Brian Luke Seaward. Pharmacology for Nurses. Jones & Bartlett Publishers=year=2014. ISBN 9781449689407.
- Murillo A, Vera-Estrella R, Barkla BJ, Méndez E, Arias CF (2015). "Identification of Host Cell Factors Associated with Astrovirus Replication in Caco-2 Cells". J. Virol. 89 (20): 10359–70. doi:10.1128/JVI.01225-15. PMC 4580174. PMID 26246569.
- Page 273 in: Lennette's Laboratory Diagnosis of Viral Infections (Fourth ed.). CRC Press. 2010. ISBN 9781420084962.
- Tuthill, Tobias J.; Groppelli, Elisabetta; Hogle, James M.; Rowlands, David J. (2010). "Picornaviruses". Current Topics in Microbiology and Immunology. 343: 43–89. doi:10.1007/82_2010_37. ISSN 0070-217X. PMC 3018333.
- Stapleford, Kenneth A.; Miller, David J. (2010). "Role of Cellular Lipids in Positive-Sense RNA Virus Replication Complex Assembly and Function". Viruses. 2 (5): 1055–1068. doi:10.3390/v2051055. ISSN 1999-4915.
- Cook, S.; Moureau, G.; Harbach, R. E.; Mukwaya, L.; Goodger, K.; Ssenfuka, F.; Gould, E.; Holmes, E. C.; de Lamballerie, X. (2009). "Isolation of a novel species of flavivirus and a new strain of Culex flavivirus (Flaviviridae) from a natural mosquito population in Uganda". Journal of General Virology. 90 (11): 2669–2678. doi:10.1099/vir.0.014183-0. ISSN 0022-1317. PMC 2885038.
- Simon-Loriere, Etienne; Holmes, Edward C. (2011). "Why do RNA viruses recombine?". Nature Reviews Microbiology. 9 (8): 617–626. doi:10.1038/nrmicro2614. ISSN 1740-1526. PMC 3324781. PMID 21725337.
- Repass GL, Palmer WC, Stancampiano FF (September 2014). "Hand, foot, and mouth disease: Identifying and managing an acute viral syndrome". Cleve Clin J Med. 81 (9): 537–43. doi:10.3949/ccjm.81a.13132. PMID 25183845.
- "Babies Born with CMV (Congenital CMV Infection)". Centers for Disease Control and Prevention. April 13, 2017. Retrieved June 17, 2017. This article incorporates public domain material from websites or documents of the Centers for Disease Control and Prevention.
- Colson P.; Richet H.; Desnues C.; Balique F.; Moal V.; Grob J.; Berbis P.; Lecoq H.; Harlé J.; Berland Y.; Raoult D. (2010). "Pepper Mild Mottle Virus, a Plant Virus Associated with Specific Immune Responses, Fever, Abdominal Pains, and Pruritus in Humans". PLoS ONE. 5 (4): e10041. doi:10.1371/journal.pone.0010041. PMC 2850318. PMID 20386604.
- "Viral Fever". Web Health Centre. Retrieved August 15, 2013.