Diversité génétique des Erythrovirus humains

Genotypes of erythrovirus B19, their geographical distribution & circulation in cases with various clinical manifestations

Erythrovirus B19 (B19V) is one of the erythroviruses known to be pathogenic in humans. B19V is classified into three distinct genotypes; 1, 2 and 3, differing from each other by 2-13 per cent. Genotype 1 consists of the prototype B19V isolates, genotype 2 comprises the A6, LaLi and their related isolates while genotype 3 includes the V9- and V9-related isolates. The classification of genotype 1 into two subtypes (1A and 1B) and genotype 3 into two subtypes (3a and 3b) with an estimated nucleotide difference of about 5 per cent has been done. Predominance of genotype 1 across all the continents is seen followed by genotypes 2 and 3. There are no disease-specific genotypes. All the three genotypes have been found in symptomatic as well as asymptomatic individuals and have been reported from several countries across the world. The prevalence of genotype 2 in older populations and its absence from current circulation in Northern Europe has also been reported. The present review focuses on geographic distribution and association of genotypes of B19V with different clinical manifestations.

Prevalence and association of human parvovirus B19V with hepatitis B and C viruses in Nigeria

Co-infection of parvovirus B19 with hepatitis B virus has been found in patients with acute and chronic hepatitis. The clinical significance of parvovirus B19 in hepatitis B co-infected patients is still controversial. In this study parvovirus B19 antibodies and DNA were investigated in serum samples from 76 patients with HBV infection, 17 with HBV/HCV co-infection and 44 healthy controls. In the sera from patients with HBV infection, anti-B19V IgM and IgG antibodies were detected in 24/76 (32%) and 25/76 (33%), in 6/17 (35%) and 8/17 (47%) of HBV/HCV co-infected patients, and in 14/44 (32%) and 12/44 (12%) of a non-hepatitis healthy controls, respectively. B19V DNA was detected in 8/76 (11%) of patients with HBV infection and in 3/17 (18%) of patients with a HBV/HCV co-infection, and in 4/44 (9%) healthy controls. The occurrence of parvovirus B19 DNA was significantly higher in patients with symptomatic HBV 4/20 (20%) compared to asymptomatic HBV carrier 4/56 (7%) (P<0.05). Ten of the positive B19V DNA sequences belonged to B19V genotype 1 while two belonged to genotype 3. The results of this study showed a significant difference in the prevalence of parvovirus B19 DNA in symptomatic HBsAg positive as compared to asymptomatic HBsAg positive individuals; however, the conclusion that parvovirus B19 infection increased the frequency of liver disease was not supported. Long-term longitudinal studies are, however, required to determine the synergistic effect of parvovirus B19 infection in HBV or HBV and HCV co-infected persons.