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Sunday 29 January 2006


- List of viruses

Viruses are obligate intracellular parasites that depend on the host cell’s metabolic machinery for their replication. They consist of a nucleic acid genome surrounded by a protein coat (called a capsid) that is sometimes encased in a lipid membrane.

Viruses are classified by their nucleic acid genome (DNA or RNA but not both), the shape of the capsid (icosahedral or helical), the presence or absence of a lipid envelope, their mode of replication, the preferred cell type for replication (called tropism), or the type of pathology.

Because viruses are only 20 to 300 nm in size, they are best visualized with the electron microscope. However, some viral particles aggregate within the cells they infect and form characteristic inclusion bodies, which may be seen with the light microscope and are useful for diagnosis.

For example, cytomegalovirus (CMV)-infected cells are enlarged and show a large eosinophilic nuclear inclusion and smaller basophilic cytoplasmic inclusions; herpesviruses form a large nuclear inclusion surrounded by a clear halo; and both smallpox and rabies viruses form characteristic cytoplasmic inclusions. Many viruses do not give rise to inclusions (e.g., Epstein Barr virus - EBV).

Viruses account for a large share of human infections. Many viruses cause transient illnesses (e.g., colds, influenza). Other viruses are not eliminated from the body and persist within cells of the host for years, either continuing to multiply (e.g., chronic infection with hepatitis B virus) or surviving in some nonreplicating form (termed latent infection) with the potential to be reactivated later.

For example, herpes zoster virus, the cause of chickenpox, can enter dorsal root ganglia and establish latency there and later be periodically activated to cause shingles, a painful skin condition.

Some viruses can transform a host cell into a tumor or cancer cell (e.g., human papillomaviruses cause benign warts and have been implicated in cervical carcinoma).

Different species of viruses can produce the same clinical picture (e.g., upper respiratory infection); conversely, a single virus can cause different clinical manifestations depending on host age or immune status (e.g., CMV).


Viral Pathogen Virus Family Genomic Type Disease Expression
Respiratory - - -
Adenovirus Adenoviridae DS DNA Upper and lower respiratory tract infections, conjunctivitis, diarrhea
Rhinovirus Picornaviridae SS RNA Upper respiratory tract infection
Coxsackievirus Picornaviridae SS RNA Pleurodynia, herpangina, hand-foot-and-mouth disease, SARS
Coronavirus Coronaviridae SS RNA Upper respiratory tract infection
Influenza viruses A, B Orthomyxoviridae SS RNA Influenza
Respiratory syncytial virus Paramyxoviridae SS RNA Bronchiolitis, pneumonia
Digestive - - -
Mumps virus Paramyxoviridae SS RNA Mumps, pancreatitis, orchitis
Rotavirus Reoviridae DS RNA Childhood diarrhea
Norwalk agent Caliciviridae SS RNA Gastroenteritis
Hepatitis A virus Picornaviridae SS RNA Acute viral hepatitis
Hepatitis B virus Hepadnaviridae DS DNA Acute or chronic hepatitis
Hepatitis D virus Viroid-like SS RNA With HBV, acute or chronic hepatitis
Hepatitis C virus Flaviviridae SS RNA Acute or chronic hepatitis
Hepatitis E virus Norwalk-like SS RNA Enterically transmitted hepatitis
Systemic with Skin Eruptions
Measles virus Paramyxoviridae SS RNA Measles (rubeola)
Rubella virus Togaviridae SS RNA German measles (rubella)
Parvovirus Parvoviridae SS DNA Erythema infectiosum, aplastic anemia
Vaccinia virus Poxviridae DS DNA Smallpox vaccine
Varicella-zoster virus Herpesviridae DS DNA C hickenpox, shingles
Herpes simplex virus 1 Herpesviridae DS DNA "Cold sore"
Herpes simplex virus 2 Herpesviridae DS DNA Genital herpes
Systemic with Hematopoietic Disorders - - -
Cytomegalovirus Herpesviridae DS DNA Cytomegalic inclusion disease
Epstein-Barr virus Herpesviridae DS DNA Infectious mononucleosis
HTLV-I Retroviridae SS RNA Adult T-cell leukemia; tropical spastic paraparesis
HIV-1 and HIV-2 Retroviridae SS RNA AIDS
Arboviral and Hemorrhagic Fevers - - -
Dengue virus 1-4 Togaviridae SS RNA Dengue, hemorrhagic fever
Yellow fever virus Togaviridae SS RNA Yellow fever
Regional hemorrhagic fever viruses Filoviridae SS RNA Ebola, Marburg disease
Hantavirus SS RNA Korean, U.S. pneumonia
Warty Growths - - -
Papillomavirus Papovaviridae DS DNA Condyloma; cervical carcinoma
Central Nervous System - - -
Poliovirus Picornaviridae SS RNA Poliomyelitis
JC virus Papovaviridae DS DNA Progressive multifocal leukoencephalopathy (opportunistic)
Arboviral encephalitis viruses Togaviridae SS RNA Eastern, Western, Venezuelan, St. Louis

Open references

- Mutualistic viruses and the heteronomy of life. Pradeu T. Stud Hist Philos Biol Biomed Sci. 2016 Oct;59:80-8. doi : 10.1016/j.shpsc.2016.02.007 PMID: 26972872 Free

Paywall References

- Understanding viruses: Philosophical investigations. Pradeu T, Kostyrka G, Dupré J. Stud Hist Philos Biol Biomed Sci. 2016 Oct;59:57-63. doi : 10.1016/j.shpsc.2016.02.008 PMID : 269752

- Marques JT, Carthew RW. A call to arms: coevolution of animal viruses and host innate immune responses. Trends Genet. 2007 Jul;23(7):359-64. PMID: 17467114