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.

Simian parvovirus infection in cynomolgus monkey heart transplant recipients causes death related to severe anemia

BACKGROUND

Simian parvovirus (SPV) was first isolated from cynomolgus monkeys. Like human parvovirus B19, this virus has a predilection for erythroid cells. During acute SPV infection, clinical signs are usually mild or inapparent, but severe anemia may occur in immunocompromised animals. We report several cases of symptomatic SPV infection in cynomolgus monkeys following heart transplantation.

METHODS

Twenty-three consecutive abdominal heterotopic heart transplants were studied. Viremia, measured by dot blot and/or PCR, and SPV-specific antibodies were determined retrospectively.

RESULTS

All except one animal were on an immunosuppressive protocol. In all, 48% (11/23) of transplant recipients had viremia with SPV detected at some point after transplant. An additional 22% seroconverted before or after transplant, and were asymptomatic without detectable SPV. Of the 11 acutely viremic animals, five were euthanized because of severe anemia attributed to SPV. The remaining 30% of the transplant recipients did not seroconvert and were asymptomatic. Of seven recipients of donor tissue from seropositive or viremic animals, five became viremic and three died with anemia. No immunosuppressive regimen was implicated in increased susceptibility; the one transplant recipient not treated with immunosuppressive agents died with anemia and acute viremia two weeks after explant of a rejected graft.

CONCLUSION

SPV is an important pathogen in surgically manipulated cynomolgus monkeys, particularly with immune compromise. Once introduced into a colony, clinically silent SPV infection could be readily transmitted within the environment. Transmission and disease occur at high frequency with an organ from a PCR-negative, seropositive donor, suggesting that latent virus can be conveyed by the organ.