Molecular mechanism underlying B19 virus inactivation and comparison to other parvoviruses.
BACKGROUND
B19 virus (B19V) is a human pathogen frequently present in blood specimens. Transmission of the virus occurs mainly via the respiratory route, but it has also been shown to occur through the administration of contaminated plasma-derived products. Parvoviridae are highly resistant to physicochemical treatments; however, B19V is more vulnerable than the rest of parvoviruses. The molecular mechanism governing the inactivation of B19V and the reason for its higher vulnerability remain unknown.


METHODS
After inactivation of B19V by wet heat and low pH, the integrity of the viral capsid was examined by immunoprecipitation with two monoclonal antibodies directed to the N-terminal of VP1 and to a conformational epitope in VP2. The accessibility of the viral DNA was quantitatively analyzed by a hybridization-extension assay and by nuclease treatment.


RESULTS
The integrity of the viral particles was maintained during the inactivation procedure; however, the capsids became totally depleted of viral DNA. The DNA-depleted capsids, although not infectious, were able to attach to target cells. Comparison studies with other members of the Parvoviridae family revealed a remarkable instability of B19V DNA in its encapsidated state.


CONCLUSIONS
Inactivation of B19V by heat or low pH is not mediated by capsid disintegration but by the conversion of the infectious virions into DNA-depleted capsids. The high instability of the viral DNA in its encapsidated state is an exclusive feature of B19V, which explains its lower resistance to inactivation treatments.
Mani
Bernhard
B
Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, 3012 Bern, Switzerland.
Gerber
Marco
M
Lieby
Patricia
P
Boschetti
Nicola
N
Kempf
Christoph
C
Ros
Carlos
C
D036022:Capsid Proteins / Q000235:genetics; D002460:Cell Line; D017931:DNA Primers; D004279:DNA, Viral / Q000235:genetics; D016731:Erythema Infectiosum / Q000517:prevention & control* / Q000635:transmission; D005434:Flow Cytometry; D006358:Hot Temperature; D006801:Humans; D006863:Hydrogen-Ion Concentration; D016732:Parvovirus B19, Human / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D016133:Polymerase Chain Reaction; D065227:Transfusion Reaction; D038301:Virus Inactivation
D036022:Capsid Proteins; D017931:DNA Primers; D004279:DNA, Viral