Parvoviridae

The virus family of parvoviruses (Parvoviridae) comprises species that are the only human pathogenic viruses to carry a single-stranded DNA genome. With a diameter of 18-26 nm, they are among the smallest viruses (parvus = small), are non-enveloped and very resistant to external influences.

One of the members of the genus "erythroviruses" is parvovirus B19, which causes erythema infectiosum (ringworm), the only human disease caused by this virus family that has been confirmed to date. Parvovirus B 19 is distributed worldwide. The seroprevalence of B 19-specific antibodies is between 40 and 60% in western industrial nations. Other parvoviruses are exclusively animal pathogens.

Parvovirus B 19 preferentially infects bone marrow erythropoid progenitor cells. Notably, productive infection is dependent on a dividing cell and, unlike papillomaviruses for example, parvovirus is unable to maintain the host cell in S phase . Accordingly, they require host cells that divide permanently.

Therefore, the "burst"-(BFU) and "colony"-forming (CFU) differentiation stages of the erythropoid progenitor cell are preferred sites of replication. Here, the virus absorbs at the blood group protein P and is then taken up endosomally. The single-stranded DNA is completed into a double strand by cellular polymerases and subsequently the mRNA is transcribed. Viral release occurs either upon apoptosis of the target cell or by vesicular transport to the cell surface.

The virus is cytotoxic to the infected cells, resulting in transient anemia in the infected host.

Histologically, large pronormoblasts with nuclear inclusion bodies and cytoplasmic vacuoles are seen in the bone marrow.

Infections with parvovirus B19 are associated with a wide range of different diseases. The course of infection and the severity of the disease depend on the immunological status of the patient.

S.a.u. Erythema infectiosum (aetiology confirmed);

s.a.u. Gloves and socks syndrome, papulopurpuric (viral genesis not certain)

S.a.u. Juvenile spring eruption

Infections during pregnancy lead in 25% of cases to the development of a fetal hydrops and in 70% to intrauterine death.

For further information see below Parvovirus B19 infection (internal medicine)

1. Martinez-Martinez P et al (2000) Infection by human parvovirus B 19:"gloves and socks" papular purpuric syndrome. Diagn Micobiol Infect Dis 36: 206-210
2. Van Rooijen MM (1999) Drug-induced papulopurpuric gloves and socks syndrome. dermatologist 50: 280-283