Genetic drift of parvovirus B19 is found in AIDS patients with persistent B19 infection

Molecular and phylogenetic analyses of human Parvovirus B19 isolated from Brazilian patients with sickle cell disease and β-thalassemia major and healthy blood donors

Human Parvovirus B19 (B19V) is a recognized cause of life-threatening conditions among patients with hemoglobinopathies. This study investigates B19V infection in patients with sickle cell disease and β-thalassemia using different experimental approaches. A total of 183 individuals (144 with sickle cell disease and 39 with β-thalassemia major) and 100 healthy blood donors were examined for B19V using anti-B19V IgG enzyme immunoassay, quantitative PCR, DNA sequencing, and phylogenetic analysis. Viremia was documented in 18.6% of patients and 1% of donors, and was generally characterized by low viral load (VL); however, acute infections were also observed. Anti-B19V IgG was detected in 65.9% of patients with sickle cell disease and in 60% of donors, whereas the patients with thalassemia exhibited relatively low seroreactivity. The seroprevalence varied among the different age groups. In patients, it progressively increased with age, whereas in donors it reached a plateau. Based on partial NS1 fragments, all isolates detected were classified as subgenotype 1A with a tendency to elicit genetically complex infections. Interestingly, quasispecies occurred in the plasma of not only patients but also donors with even higher heterogeneity. The partial NS1 sequence examined did not exhibit positive selection. Quantitation of B19V with a conservative probe is a technically and practically useful approach. The extensive spread of B19V subgenotype 1A in patients and donors and its recent introduction into the countryside of the São Paulo State, Brazil were demonstrated; however, it is difficult to establish a relationship between viral sequences and the clinical outcomes of the infection.

Cluster of parvovirus infection among hospital staff working in coronary care units

BACKGROUND

Parvovirus B19 is associated with erythema infectiosum in children or arthralgia and arthritis in adults. The virus is relatively conserved and nucleotide identity is expected in viruses that are epidemiologically related. Here, we describe the first cluster of parvovirus infection among hospital staff documented in Taiwan.

METHODS

Active surveillance was conducted in coronary care units (CCUs) at a 2200-bed teaching hospital for 1 month in 2007. A case defined clinically as occurring in a patient or staff in CCUs with new onset of fever or rash. Serum was tested for parvovirus B19 IgM and IgG by immunoblotting and DNA by nested polymerase chain reaction. When viremia was detected, nucleotide sequences were analyzed and compared with those of two clinical isolates. The attack rate was defined as the cumulative incidence of acute infection in CCU staff and patients during the study period.

RESULTS

Among 57 staff and 15 patients, five nurses met the clinical case definition. Three had acute infection as demonstrated by viral DNA and IgM. The attack rate was 5.3% for the staff and zero for patients. Seroprevalence rate was lower in staff than in patients (26.3%vs. 53.3%). The isolates collected from three cases were highly similar to a community isolate, and they varied with each other by 2-6 nucleotides. The isolate collected from a nurse was identical to that from her friend 3 weeks apart and was concordant with mutual transmission. A sequence with 45 nucleotide variations was identified from a staff member with chronic infection who was negative for IgM and had only weak IgG anti-VP1 reaction with immunoblotting. We did not find any patient as the source of infection.

CONCLUSION

We identified a cluster of parvovirus infection that was caused by three circulating strains which did not support the hypothesis of transmission of a single strain in CCUs.