Laboratory Medicine and Molecular Diagnostics Rajiv Gandhi Centre for Biotechnology (RGCB), Thiruvananthapuram, 695585, India.
Teagasc Food Research Centre, Moorepark, Fermoy, Co. Cork, Ireland.
Virol J. 2021 May 5;18(1):96. doi: 10.1186/s12985-021-01569-1.
Human parvovirus B19V is a DNA virus, and a member of the family Parvoviridae, that causes various clinical manifestations, from asymptomatic to persistent infection that is associated with different autoimmune diseases. The parvovirus B19 evolves with a very high mutation rate that is closer to those of existing RNA viruses. Globally circulating B19V is currently classified into three genotypes, but their distribution is not spatially and temporally correlated. Except for a few recent reports on B19V entry into the human host and its genetic diversity, there is a lack of sufficient studies on this virus from distinct geographical locations and no clear understanding of its evolution has been documented.
To better understand the evolution of the Human parvo B19V virus from India's southern part, a geographically distinct location with no reports of B19V genomes, we have screened for B19V in 456 suspected cases using VP1/2 surface marker genes, and its characteristics were studied in detail. Amongst 456 clinically suspected B19V samples, 7.2% (33/456) were found positive by nested PCR (nPCR) were subsequently validated by real-time PCR, Sanger sequencing, and metagenome analysis.
Human parvovirus B19 infection was shown among 33 of 456 patients when tested by nPCR; 30 among these were also positive by qPCR and were subsequently confirmed by sequencing 75% nPCR positive samples and 76% qPCR positive samples were from patients with age. ≥ 50 years respectively (Additional file 1: Table S1). The complete VP1/2 gene assembly from the South Indian strain showed three novel mutations (T122A, V128I, I283V), which might significantly impact the stability and virulence of the B19V virus circulating in this part of the world. These mutations might be crucial for its adaptive evolutionary strategies facilitating the spread and infectivity potential of the virus. In maximum likelihood phylogeny of VP1/2 sequences, the South Indian B19V strain forms a separate clade closer to the existing genotype two strains circulating worldwide.
Our study contributes to a better understanding of the human parvovirus's genetic and evolutionary characteristics in South India. Also, it highlights the possibility that a positive selection pressure acting on VP1/2 could increase the survival and replication capabilities of the viruses.
人类细小病毒 B19V 是一种 DNA 病毒，属于细小病毒科，可引起各种临床表现，从无症状到持续性感染，与不同的自身免疫性疾病有关。细小病毒 B19 的进化具有非常高的突变率，与现有的 RNA 病毒更为接近。目前，全球循环的 B19V 分为三个基因型，但它们的分布在空间和时间上没有相关性。除了最近有少数关于 B19V 进入人类宿主及其遗传多样性的报道外，对于来自不同地理位置的这种病毒，缺乏足够的研究，也没有明确记录其进化情况。
为了更好地了解来自印度南部这一地理位置独特、没有 B19V 基因组报告的地区的人类细小病毒 B19 的进化情况，我们使用 VP1/2 表面标记基因对 456 例疑似病例进行了 B19V 筛查，并对其特征进行了详细研究。在 456 例临床疑似 B19V 样本中，巢式 PCR（nPCR）检测到 7.2%（33/456）为阳性，随后通过实时 PCR、Sanger 测序和宏基因组分析进行了验证。
nPCR 检测到 456 例患者中有 33 例存在人类细小病毒 B19 感染；其中 30 例通过 qPCR 也呈阳性，并随后通过测序进行了确认。75%的 nPCR 阳性样本和 76%的 qPCR 阳性样本来自年龄≥50 岁的患者（附加文件 1：表 S1）。来自印度南部的菌株的完整 VP1/2 基因组装显示了三个新突变（T122A、V128I、I283V），这可能显著影响该地区循环的 B19V 病毒的稳定性和毒力。这些突变可能对病毒的适应性进化策略至关重要，有助于病毒的传播和感染能力。在 VP1/2 序列的最大似然系统发育树中，印度南部的 B19V 菌株形成了一个单独的分支，与全球循环的现有基因型 2 菌株更为接近。
本研究有助于更好地了解印度南部人类细小病毒的遗传和进化特征。此外，它还强调了对 VP1/2 施加正向选择压力可能会增加病毒的生存和复制能力。
