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Until recently, B19 virus was considered to be the only human pathogen of the genus erythrovirus. However, other non-B19 virus strains, such as V9, have now been isolated and are thought to cause infections clinically and serologically indistinguishable from those caused by B19 virus. Whereas B19 virus related isolates have a low genetic diversity of only 1-2%, nucleotide disparity of up to 12% was found for the new isolates, suggesting that non-B19 virus isolates may not be detectable using B19 virus specific PCR methods. To overcome this problem, we designed consensus primers and probes to enable the simultaneous detection of both B19 and non-B19 virus and subsequent discrimination of the two lineages by melting temperature (T(m)) analysis. A total of 196 clinical specimens, from 185 patients with a history of or an anamnesis resembling B19 virus infection, were analyzed using the consensus PCR test. Erythrovirus DNA was detected in 37 of these samples and was found to be B19 virus specific in each case, confirming previous results using B19 virus specific PCR. Although no non-B19 virus DNA was detected in any of the clinical samples tested in this study, more extensive studies are warranted. The routine use of erythrovirus consensus PCR in the diagnosis of B19 virus infection should provide valuable information on the epidemiology and clinical role of non-B19 virus isolates; its use in screening would increase the safety of blood products., (Copyright 2004 Wiley-Liss, Inc.)

Diagnosis of erythrovirus B19 relies on serology and the detection of viral DNA. These techniques were believed to detect all field isolates because erythrovirus B19 has been known to undergo little genetic variation (1-2%). Recently, a distinct erythrovirus isolate termed V9, markedly different from erythrovirus B19 (>11% nucleotide disparity), was isolated from a child in France suffering from transient aplastic anemia. Standard PCR assays and serological tests failed to demonstrate an acute erythrovirus B19 infection. Subsequent sequencing of the erythrovirus V9 genome shows that the nucleotide discrepancies encompass the entire genome, indicating that standard erythrovirus B19 PCR assays will not reliably detect erythrovirus V9 DNA. As a tool for studying the epidemiological role and medical importance of this erythrovirus variant, a PCR assay is described that allows simultaneous detection of, and distinction between, erythrovirus B19 and the V9 isolate. Examination of 100 erythrovirus B19 IgM positive samples as well as plasma pools representing 100,000 Danish blood donor units for the presence of B19 and V9 DNA was performed. Despite the apparent absence of erythrovirus V9 in the clinical samples at present, the DNA sequence variability demonstrates that the erythrovirus group may be more divergent than thought previously and the child harboring this isolate may herald erythrovirus V9 as a possible emerging virus., (Copyright 2001 Wiley-Liss, Inc.)