The presence of human erythrovirus DNA in 2,440 blood donations from the United Kingdom and subSaharan Africa (Ghana, Malawi, and South Africa) was screened. Sensitive qualitative and real-time quantitative PCR assays revealed a higher prevalence of persistent infection with the simultaneous presence of immunoglobulin G (IgG) and viral DNA (0.55 to 1.3%) than previously reported. This condition was characterized by a low viral load (median, 558 IU/ml; range, 42 to 135,000 IU/ml), antibody-complexed virus, free specific IgG, and potentially infectious free virus. Human erythrovirus genotype 1 (formerly parvovirus B19) was prevalent in the United Kingdom, Malawi, and South Africa. In contrast, only human erythrovirus genotype 3 (erythrovirus variant V9) was prevalent in Ghana. Genotype 3 had considerable genetic diversity, clustering in two probable subtypes. Genotype 1-based antibody assays failed to detect 38.5% of Ghanaian samples containing antibodies to genotype 3 virus but did not fail to detect cases of persistent infection. This study indicates a potential African origin of genotype 3 human erythrovirus and considerable shortcomings in the tools currently used to diagnose erythrovirus infection. Human erythrovirus (formerly parvovirus B19) is a member of the genus Erythrovirus within the family Parvoviridae (24).Erythrovirus infection occurs frequently in humans. The prevalence of specific immunoglobulin G (IgG) antibodies is 2 to 15% in young children, 30 to 60% in adults, and more than 85% in those 70 years old or older (14). The linear singlestranded DNA genome of this small, nonenveloped virus is about 5 kb long and contains two large open reading frames (ORFs). The first ORF encodes nonstructural protein NS1, and the second one encodes both major VP2 and minor VP1 structural capsid proteins. VP1 consists of a unique sequence of 227 amino acids (VP1u) and is followed by the entire VP2 sequence (554 amino acids). Two additional ORFs encoding small proteins (7.5 and 11 kDa) with unknown functions have also been described (see reference 14 for a review).Following viral infection in immunocompetent individuals, the predominant immune response is a humoral response, which is assumed to confer protective, lifelong immunity. The early IgM response is directed against VP2, while the mature response mostly involves the production of IgG to VP1 (see reference 14 for a review). Several VP2 and VP1u regions containing neutralizing epitopes have been identified (10, 32, 43). However, neutralizing linear epitopes seem to cluster in the N terminus of VP1u and the VP1-VP2 junction regions and to elicit a more efficient response than the epitopes in the VP2 region, which are mainly conformational epitopes (21,26,28,31,36). The inability to develop an efficient neutralizing immune response, as observed mainly in immunosuppressed individuals but also in otherwise healthy individuals, may result in the failure to eliminate the virus, thus leading to persistent infection and the possible occurrence of chronic diseases, suc...

In this study anti-klebsiella Ig A values were compared in 40 patients with definite diagnosis of ankylosing spondylitis and a control group of 40 healthy subjects. Anti-Klebsiella Ig A antibody values were significantly higher in patients with ankylosing spondylitis as compared to the control group (p < 0.001). Correlation between these antibodies and erythrocyte sedimentation rate, CRP, serum Ig A, HLA B 27, age, sex and disease duration was searched, but no correlation was found. In our opinion, these results support the suggestion that inflammatory response in ankylosing spondylitis is triggered by Klebsiella but is insufficient to prove the causal relationship between ankylosing spondylitis and Klebsiella.