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Microbiology, 2021

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6.1 • Viruses 227<br />

LINK TO LEARNING<br />

Explore the latest virus taxonomy (https://www.openstax.org/l/22virustaxon) at the ICTV website.<br />

Aside from formal systems of nomenclature, viruses are often informally grouped into categories based on<br />

chemistry, morphology, or other characteristics they share in common. Categories may include naked or<br />

enveloped structure, single-stranded (ss) or double-stranded (ds) DNA or ss or ds RNA genomes, segmented or<br />

nonsegmented genomes, and positive-strand (+) or negative-strand (−) RNA. For example, herpes viruses can<br />

be classified as a dsDNA enveloped virus; human immunodeficiency virus (HIV) is a +ssRNA enveloped virus,<br />

and tobacco mosaic virus is a +ssRNA virus. Other characteristics such as host specificity, tissue specificity,<br />

capsid shape, and special genes or enzymes may also be used to describe groups of similar viruses. Table 6.2<br />

lists some of the most common viruses that are human pathogens by genome type.<br />

Common Pathogenic Viruses<br />

Genome Family Example Virus Clinical Features<br />

Poxviridae Orthopoxvirus Skin papules, pustules, lesions<br />

dsDNA,<br />

enveloped<br />

Poxviridae Parapoxvirus Skin lesions<br />

Herpesviridae<br />

Simplexvirus<br />

Cold sores, genital herpes, sexually<br />

transmitted disease<br />

Adenoviridae Atadenovirus Respiratory infection (common cold)<br />

dsDNA,<br />

naked<br />

Papillomaviridae<br />

Papillomavirus<br />

Genital warts, cervical, vulvar, or<br />

vaginal cancer<br />

Reoviridae<br />

Reovirus<br />

Gastroenteritis severe diarrhea<br />

(stomach flu)<br />

ssDNA,<br />

naked<br />

Parvoviridae<br />

Parvoviridae<br />

Adeno-associated<br />

dependoparvovirus A<br />

Adeno-associated<br />

dependoparvovirus B<br />

Respiratory tract infection<br />

Respiratory tract infection<br />

dsRNA,<br />

naked<br />

Reoviridae Rotavirus Gastroenteritis<br />

Picornaviridae Enterovirus C Poliomyelitis<br />

+ssRNA,<br />

naked<br />

Picornaviridae<br />

Rhinovirus<br />

Upper respiratory tract infection<br />

(common cold)<br />

Picornaviridae Hepatovirus Hepatitis<br />

+ssRNA,<br />

enveloped<br />

Togaviridae Alphavirus Encephalitis, hemorrhagic fever<br />

Togaviridae Rubivirus Rubella

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