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Parvoviruses

Parvoviruses. Chapter 31. Properties of Parvoviruses. Structure Icosahedral 18-26 nm diameter Single-stranded DNA , 5.6 kb Two proteins Nonenveloped Classification Parvoviridae (vertebrates) Parvovirus Erythrovirus Dependovirus (requires helper virus , such as an adenovirus)

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Parvoviruses

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  1. Parvoviruses • Chapter 31

  2. Properties of Parvoviruses • Structure • Icosahedral • 18-26 nm diameter • Single-stranded DNA, 5.6 kb • Two proteins • Nonenveloped • Classification • Parvoviridae (vertebrates) • Parvovirus • Erythrovirus • Dependovirus (requires helper virus, such as an adenovirus) • Densovirinae (insects)

  3. Properties of Parvoviruses • Replication • Attachment and entry • Translocation of viral DNA into nucleus • Transcription and translation of viral nonstructural protein and nucleocapsid • DNA replication • Virus assembly (nucleus) • Release from the cell through lysis

  4. Parvovirus Infections in Humans • Diseases • Fifth disease (cutaneous rash) • Transient aplastic crisis (severe acute anemia) • Pure red cell aplasia (chronic anemia) • Hydrops fetalis (fatal fetal anemia) • B19 virus most common • Fifth Disease • Targets red blood cell progenitors • Pain in joints • Results in lysis of cells, thus depleting source of mature red cells • Anemia ensues • Rarely fatal and without complications Fifth Disease (parvovirus B19)

  5. Parvovirus Infections in Humans • Transient aplastic crisis • B19 infection of those with other hemolytic anemias • Sickle cell disease • Thalassemias • Can complicate crises • Sometimes fatal • Infection of immunodeficient patients • Can cause persistent infection in bone marrow • Suppress red cell maturation • Leads to anemia • Infection during pregnancy • Can cause fetal anemia • Usually not fatal to fetus

  6. Laboratory Diagnosis • PCR is most sensitive • Most useful during viremia • Otherwise, requires tissue biopsy or bone marrow tap • Serological testing for IgM • Determines recent infection • IgG testing is not informative

  7. Epidemiology • B19 virus is common and widespread • Most adults have been infected • Most infections are subclinical • IgG is detectable in most healthy people • Sporadic outbreaks, usually among children, occur each year • Transmission from patient to health care staff is not uncommon • Role in nosocomial transmission to other patients • Treatment • Address symptoms • Transfusions for serious anemic crises • Commercially-available neutralizing IgG (passive immunization) • Prevention and control • No vaccine available for human parvoviruses • Good hygienic practices mitigate transmission

  8. Canine Parvovirus • Canine parvovirus (CPV-2) appears to be a mutant strain of feline parvovirus • Some breeds are more sensitive to CPV infection • The virus is considered ubiquitous in the environment • It is a hardy virus • Can survive for extended periods on fomites • Transmitted through oral-fecal route • Symptoms: dehydration, vomiting, bloody diarrhea • Vaccine is available

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