Genetic Variants of Human Parvovirus B19 in South Africa: Cocirculation of Three Genotypes and Identification of a Novel Subtype of Genotype 1

Abstract

Parvovirus B19 comprises three distinct genotypes (1, 2, and 3). The distribution of B19 genotypes has not before been examined in South Africa. Two hundred thirty-nine laboratory samples submitted to a diagnostic virology laboratory for parvovirus DNA detection were analyzed retrospectively. Of the 53 PCR-positive samples investigated, 40 (75.4%) were identified as genotype 1 by genotype-specific PCR or consensus NS1 PCR and sequencing and 3 (5.7%) as genotype 2 and 10 (18.9%) as genotype 3 by analysis of NS1 sequences. Furthermore, phylogenetic analysis identified two genotype 1 sequences which were distinct from the previously described genotypes 1A and 1B. Interestingly, a genotype 2 virus was detected in the serum of an 11-year-old child, providing evidence for its recent circulation. This is the first study to demonstrate the concurrent circulation of all three genotypes of B19 in South Africa and the provisional identification of a novel subtype of genotype 1. The implications of parvovirus B19 variation are discussed.

Keeping Pace with Parvovirus B19 Genetic Variability: a Multiplex Genotype-Specific Quantitative PCR Assay

“…On the whole, the genetic diversity of genotype 1a remains low, and primers and probes are expected to recognize targets with high expectation values. The distance of genotype 1b is about 4% from genotype 1a, but the circulation of this subgenotype, and of additional rarer variants still within the genotype 1 cluster, seems to be geographically restricted (5,8). Genotypes 2 and 3 pose different problems.…”

“…However, the advantage to perform B19V detection with a validated qPCR methodology able to discriminate and quantitate different genotypes derives from two considerations. First, variant genotypes are known to circulate at higher frequencies in areas other than Europe or the United States, and in addition the changing demographic and epidemiological scenario will probably lead to a more global circulation of genotype 3 (5,6,8,9). Second, a reliable viral diagnosis should be able to detect variant genotypes even in particular sporadic clinical situations when standard assays, focused on genotype 1, may fail in B19V detection (7,10,23,24).…”

“…Furthermore, genotype 2 is considered an older genotype, likely to be frequently present as part of the human persistent virome (bioportfolio) (22) but infrequently found as circulating virus. Genotype 3 is a circulating virus that can be prevalent in defined geographic settings (8,9). Their higher sequence divergence may pose diagnostic challenges, and primers and probes may recognize targets with lower expectation values (23,24).…”

“…Within genotype 3, two distinct subtypes are usually referred to as genotypes 3a and 3b (6). All B19V genotypes appear to cocirculate, but their relative frequencies are strikingly different: genotype 1a is ubiquitous worldwide, genotype 2 is rare and sporadically detected in different geographic settings, including Europe, and genotypes 3a and 3b are detected at higher frequencies in western Africa and at lower frequencies in other geographic areas (7)(8)(9)(10).…”

Viruses of the Parvoviridae Family: Molecular Genetical Aspects of Reproduction and Medical Importance

“…Данные о молекулярно-биологических и ви-русологических характеристиках вируса, эпи-демиологических и клинических особеннос-тях парвовирусной В19 инфекции освещены в многочисленных работах как зарубежных, так и отечественных авторов [14,20,39,68], и были представлены нами ранее [2,3].…”