Rhesus and pig-tailed macaque parvoviruses: identification of two new members of the erythrovirus genus in monkeys

Globoside Is an Essential Intracellular Factor Required for Parvovirus B19 Endosomal Escape

Human parvovirus B19 (B19V), like most parvoviruses, possesses phospholipase A2 (PLA2) activity, which is thought to mediate endosomal escape by membrane disruption. Here, we challenge this model and find evidence for a mechanism of B19V entry mediated by the glycosphingolipid globoside without endosome disruption and retrograde transport to the Golgi. We show that B19V PLA2 activity requires specific calcium levels and pH conditions that are not optimal in endosomes. Accordingly, endosomal membrane integrity was maintained during B19V entry. Furthermore, endosomes remained intact when loaded with MS2 bacteriophage particles pseudotyped with multiple B19V PLA2 subunits, providing superior enzymatic potential compared to native B19V. In globoside knockout cells, incoming viruses are arrested in the endosomal compartment and the infection is blocked. Infection can be rescued by promoting endosomal leakage with polyethyleneimine (PEI), demonstrating the essential role of globoside in facilitating endosomal escape. Incoming virus colocalizes with Golgi markers and interfering with Golgi function blocks infection, suggesting that globoside-mediated entry involves the Golgi compartment, which provides conditions favorable for the lipolytic PLA2. Our study challenges the current model of B19V entry and identifies globoside as an essential intracellular receptor required for endosomal escape.

A Conserved Receptor-Binding Domain in the VP1u of Primate Erythroparvoviruses Determines the Marked Tropism for Erythroid Cells

Parvovirus B19 (B19V) is a human pathogen with a marked tropism for erythroid progenitor cells (EPCs). The N-terminal of the VP1 unique region (VP1u) contains a receptor-binding domain (RBD), which mediates virus uptake through interaction with an as-yet-unknown receptor (VP1uR). Considering the central role of VP1uR in the virus tropism, we sought to investigate its expression profile in multiple cell types. To this end, we established a PP7 bacteriophage-VP1u bioconjugate, sharing the size and VP1u composition of native B19V capsids. The suitability of the PP7-VP1u construct as a specific and sensitive VP1uR expression marker was validated in competition assays with B19V and recombinant VP1u. VP1uR expression was exclusively detected in erythroid cells and cells reprogrammed towards the erythroid lineage. Sequence alignment and in silico protein structure prediction of the N-terminal of VP1u (N-VP1u) from B19V and other primate erythroparvoviruses (simian, rhesus, and pig-tailed) revealed a similar structure characterized by a fold of three or four α-helices. Functional studies with simian parvovirus confirmed the presence of a conserved RBD in the N-VP1u, mediating virus internalization into human erythroid cells. In summary, this study confirms the exclusive association of VP1uR expression with cells of the erythroid lineage. The presence of an analogous RBD in the VP1u from non-human primate erythroparvoviruses emphasizes their parallel evolutionary trait and zoonotic potential.

Small but mighty: old and new parvoviruses of veterinary significance

In line with the Latin expression "sed parva forti" meaning "small but mighty," the family Parvoviridae contains many of the smallest known viruses, some of which result in fatal or debilitating infections. In recent years, advances in metagenomic viral discovery techniques have dramatically increased the identification of novel parvoviruses in both diseased and healthy individuals. While some of these discoveries have solved etiologic mysteries of well-described diseases in animals, many of the newly discovered parvoviruses appear to cause mild or no disease, or disease associations remain to be established. With the increased use of animal parvoviruses as vectors for gene therapy and oncolytic treatments in humans, it becomes all the more important to understand the diversity, pathogenic potential, and evolution of this diverse family of viruses. In this review, we discuss parvoviruses infecting vertebrate animals, with a special focus on pathogens of veterinary significance and viruses discovered within the last four years.

Identification of a Novel Ichthyic Parvovirus in Marine Species in Hainan Island, China

Parvoviruses are a diverse group of viruses that are capable of infecting a wide range of animals. In this study, we report the discovery of a novel parvovirus, tilapia parvovirus HMU-HKU, in the fecal samples of crocodiles and intestines of tilapia in Hainan Province, China. The novel parvovirus was firstly identified from crocodiles fed with tilapia using next-generation sequencing (NGS). Screening studies revealed that the prevalence of the novel parvovirus in crocodile feces samples fed on tilapia (75–86%) was apparently higher than that in crocodiles fed with chicken (4%). Further studies revealed that the prevalence of the novel parvovirus in tilapia feces samples collected at four areas in Hainan Province was between 40 and 90%. Four stains of the novel parvovirus were identified in this study based on sequence analyses of NS1 and all the four strains were found in tilapia in contrast only two of them were detected in crocodile feces. The nearly full-length genome sequence of the tilapia parvovirus HMU-HKU-1 was determined and showed less than 45.50 and 40.38% amino acid identity with other members of Parvoviridae in NS1 and VP1 genes, respectively. Phylogenetic analysis based on the complete helicase domain amino acid sequences showed that the tilapia parvovirus HMU-HKU-1 formed a relatively independent branch in the newly proposed genus Chaphamaparvovirus in the subfamily Hamaparvovirinae according to the ICTV’s most recent taxonomic criteria for Parvoviridae classification. Tilapia parvovirus HMU-HKU-1 likely represented a new species within the new genus Chaphamaparvovirus. The identification of tilapia parvovirus HMU-HKU provides further insight into the viral and genetic diversity of parvoviruses and its infections in tilapia populations need to be evaluated in terms of pathogenicity and production losses in tilapia farming.

Bocaparvovirus, Erythroparvovirus and Tetraparvovirus in New World Primates from Central America

Parvoviruses in the genera Bocaparvovirus (HBoV), Erythroparvovirus (B19) and Tetraparvovirus (PARV4) are the only autonomous parvoviruses known to be associated with human and non-human primates based on studies and clinical cases in humans worldwide and non-human primates in Asia and Africa. Here, the presence of these agents with pathogenic potential was assessed by PCR in blood and faeces from 55 howler monkeys, 112 white-face monkeys, 3 squirrel monkeys and 127 spider monkeys in Costa Rica and El Salvador. Overall, 3.7% (11/297) of the monkeys had HboV DNA, 0.67% (2/297) had B19 DNA, and 14.1% (42/297) had PARV4 DNA, representing the first detection of these viruses in New World Primates (NWP). Sex was significantly associated with the presence of HBoV, males having greater risk up to nine times compared with females. Captivity was associated with increased prevalence for PARV4 and when all viruses were analysed together. This study provides compelling molecular evidence of parvoviruses in NWPs and underscores the importance of future research aimed at understanding how these viruses behave in natural environments of the Neotropics and what variables may favour their presence and transmission.

Cynomolgus monkeys (Macaca fascicularis) experimentally infected with B19V and hepatitis A virus: no evidence of the co-infection as a cause of acute liver failure

This study was conducted to analyse the course and the outcome of the liver disease in the co-infected animals in order to evaluate a possible synergic effect of human parvovirus B19 (B19V) and hepatitis A virus (HAV) co-infection. Nine adult cynomolgus monkeys were inoculated with serum obtained from a fatal case of B19V infection and/or a faecal suspension of acute HAV. The presence of specific antibodies to HAV and B19V, liver enzyme levels, viraemia, haematological changes, and necroinflammatory liver lesions were used for monitoring the infections. Seroconversion was confirmed in all infected groups. A similar pattern of B19V infection to human disease was observed, which was characterised by high and persistent viraemia in association with reticulocytopenia and mild to moderate anaemia during the period of investigation (59 days). Additionally, the intranuclear inclusion bodies were observed in pro-erythroblast cell from an infected cynomolgus and B19V Ag in hepatocytes. The erythroid hypoplasia and decrease in lymphocyte counts were more evident in the co-infected group. The present results demonstrated, for the first time, the susceptibility of cynomolgus to B19V infection, but it did not show a worsening of liver histopathology in the co-infected group.

Molecular epidemiology of seal parvovirus, 1988-2014

A novel parvovirus was discovered recently in the brain of a harbor seal (Phoca vitulina) with chronic meningo-encephalitis. Phylogenetic analysis of this virus indicated that it belongs to the genus Erythroparvovirus, to which also human parvovirus B19 belongs. In the present study, the prevalence, genetic diversity and clinical relevance of seal parvovirus (SePV) infections was evaluated in both harbor and grey seals (Halichoerus grypus) that lived in Northwestern European coastal waters from 1988 to 2014. To this end, serum and tissue samples collected from seals were tested for the presence of seal parvovirus DNA by real-time PCR and the sequences of the partial NS gene and the complete VP2 gene of positive samples were determined. Seal parvovirus DNA was detected in nine (8%) of the spleen tissues tested and in one (0.5%) of the serum samples tested, including samples collected from seals that died in 1988. Sequence analysis of the partial NS and complete VP2 genes of nine SePV revealed multiple sites with nucleotide substitutions but only one amino acid change in the VP2 gene. Estimated nucleotide substitution rates per year were 2.00 × 10(-4) for the partial NS gene and 1.15 × 10(-4) for the complete VP2 gene. Most samples containing SePV DNA were co-infected with phocine herpesvirus 1 or PDV, so no conclusions could be drawn about the clinical impact of SePV infection alone. The present study is one of the few in which the mutation rates of parvoviruses were evaluated over a period of more than 20 years, especially in a wildlife population, providing additional insights into the genetic diversity of parvoviruses.

Novel B19-like parvovirus in the brain of a harbor seal

Using random PCR in combination with next-generation sequencing, a novel parvovirus was detected in the brain of a young harbor seal (Phoca vitulina) with chronic non-suppurative meningo-encephalitis that was rehabilitated at the Seal Rehabilitation and Research Centre (SRRC) in the Netherlands. In addition, two novel viruses belonging to the family Anelloviridae were detected in the lungs of this animal. Phylogenetic analysis of the coding sequence of the novel parvovirus, tentatively called Seal parvovirus, indicated that this virus belonged to the genus Erythrovirus, to which human parvovirus B19 also belongs. Although no other seals with similar signs were rehabilitated in SRRC in recent years, a prevalence study of tissues of seals from the same area collected in the period 2008-2012 indicated that the Seal parvovirus has circulated in the harbor seal population at least since 2008. The presence of the Seal parvovirus in the brain was confirmed by real-time PCR and in vitro replication. Using in situ hybridization, we showed for the first time that a parvovirus of the genus Erythrovirus was present in the Virchow-Robin space and in cerebral parenchyma adjacent to the meninges. These findings showed that a parvovirus of the genus Erythrovirus can be involved in central nervous system infection and inflammation, as has also been suspected but not proven for human parvovirus B19 infection.

Parvoviruses: structure and infection

Parvoviruses package a ssDNA genome. Both nonpathogenic and pathogenic members exist, including those that cause fetal infections, encompassing the entire spectrum of virus phenotypes. Their small genomes and simple coding strategy has enabled functional annotation of many steps in the infectious life cycle. They assemble a multifunctional capsid responsible for cell recognition and the transport of the packaged genome to the nucleus for replication and progeny virus production. It is also the target of the host immune response. Understanding how the capsid structure relates to the function of parvoviruses provides a platform for recombinant engineering of viral gene delivery vectors for the treatment of clinical diseases, and is fundamental for dissecting the viral determinants of pathogenicity. This review focuses on our current understanding of parvovirus capsid structure and function with respect to the infectious life cycle.

Chipmunk parvovirus is distinct from members in the genus Erythrovirus of the family Parvoviridae

The transcription profile of chipmunk parvovirus (ChpPV), a tentative member of the genus Erythrovirus in the subfamily Parvovirinae of the family Parvoviridae, was characterized by transfecting a nearly full-length genome. We found that it is unique from the profiles of human parvovirus B19 and simian parvovirus, the members in the genus Erythrovirus so far characterized, in that the small RNA transcripts were not processed for encoding small non-structural proteins. However, like the large non-structural protein NS1 of the human parvovirus B19, the ChpPV NS1 is a potent inducer of apoptosis. Further phylogenetic analysis of ChpPV with other parvoviruses in the subfamily Parvovirinae indicates that ChpPV is distinct from the members in genus Erythrovirus. Thus, we conclude that ChpPV may represent a new genus in the family Parvoviridae.

The expanding range of parvoviruses which infect humans

The first human parvoviruses to be described (1960s) were the adeno-associated viruses (AAVs, now classed as dependoviruses), originally identified as contaminants of cell cultures, followed by parvovirus B19 (B19V) in 1974, the first parvovirus to be definitively shown to be pathogenic. More recently two new groups of parvoviruses, the human bocaviruses (HuBoV) and the Parv4 viruses have been identified. These four groups of human viruses are all members of different genera within the Parvovirus family, and have very different biology, epidemiology and disease associations from each other. This review will provide an overview of the virological, pathogenic and clinical features of the different human paroviruses, and how these new viruses and their variants fit into the current understanding of parvovirus infection.

Emerging and reemerging infectious diseases of nonhuman primates in the laboratory setting

Despite numerous advances in the diagnosis and control of infectious diseases of nonhuman primates in the laboratory setting, a number of infectious agents continue to plague colonies. Some, such as measles virus and Mycobacterium tuberculosis, cause sporadic outbreaks despite well-established biosecurity protocols, whereas others, such as retroperitoneal fibromatosis-associated herpesvirus, have only recently been discovered, often as a result of immunosuppressive experimental manipulation. Owing to the unique social housing requirements of nonhuman primates, importation of foreign-bred animals, and lack of antemortem diagnostic assays for many new diseases, elimination of these agents is often difficult or impractical. Recognition of these diseases is therefore essential because of their confounding effects on experimental data, impact on colony health, and potential for zoonotic transmission. This review summarizes the relevant pathology and pathogenesis of emerging and reemerging infectious diseases of laboratory nonhuman primates.

Widespread infection with homologues of human parvoviruses B19, PARV4, and human bocavirus of chimpanzees and gorillas in the wild

Infections with human parvoviruses B19 and recently discovered human bocaviruses (HBoVs) are widespread, while PARV4 infections are transmitted parenterally and prevalent specifically in injecting drug users and hemophiliacs. To investigate the exposure and circulation of parvoviruses related to B19 virus, PARV4, and HBoV in nonhuman primates, plasma samples collected from 73 Cameroonian wild-caught chimpanzees and gorillas and 91 Old World monkey (OWM) species were screened for antibodies to recombinant B19 virus, PARV4, and HBoV VP2 antigens by enzyme-linked immunosorbent assay (ELISA). Moderate to high frequencies of seroreactivity to PARV4 (63% and 18% in chimpanzees and gorillas, respectively), HBoV (73% and 36%), and B19 virus (8% and 27%) were recorded for apes, while OWMs were uniformly negative (for PARV4 and B19 virus) or infrequently reactive (3% for HBoV). For genetic characterization, plasma samples and 54 fecal samples from chimpanzees and gorillas collected from Cameroonian forest floors were screened by PCR with primers conserved within Erythrovirus, Bocavirus, and PARV4 genera. Two plasma samples (chimpanzee and baboon) were positive for PARV4, while four fecal samples were positive for HBoV-like viruses. The chimpanzee PARV4 variant showed 18% and 15% nucleotide sequence divergence in NS and VP1/2, respectively, from human variants (9% and 7% amino acid, respectively), while the baboon variant was substantially more divergent, mirroring host phylogeny. Ape HBoV variants showed complex sequence relationships with human viruses, comprising separate divergent homologues of HBoV1 and the recombinant HBoV3 species in chimpanzees and a novel recombinant species in gorillas. This study provides the first evidence for widespread circulation of parvoviruses in primates and enables future investigations of their epidemiology, host specificity, and (co)evolutionary histories.

Novel parvovirus and related variant in human plasma

We report a novel parvovirus (PARV4) and related variants in pooled human plasma used in the manufacture of plasma-derived medical products. Viral DNA was detected by using highly selective polymerase chain reaction assays; 5% of pools tested positive, and amounts of DNA ranged from <500 copies/mL to >10⁶ copies/mL plasma.

Comparison of the transcription profile of simian parvovirus with that of the human erythrovirus B19 reveals a number of unique features

Simian parvovirus (SPV) is a member of the genus Erythrovirus and is closely related to the human parvovirus B19. Natural and experimental infection of monkeys with SPV resembles B19 infection of human. We report a detailed characterization of the viral RNAs and proteins generated following transfection of cloned SPV into COS cells and SPV infection of the human erythroid progenitor line UT-7/Epo-S1. SPV and B19 are 50% identical at the nucleotide level, and although their basic transcription and protein expression profiles were generally similar, there were also significant differences. SPV pre-mRNAs contain three introns, compared to two found for B19: an additional intron was found within the capsid-coding region. RNAs in which this intron was spliced were abundant and encoded the SPV 14-kDa protein (analogous to the B19 11-kDa protein), which initiated at an AUG in the exon preceding the third intron. Unlike B19, SPV RNAs were also spliced between the donor of the first intron and the acceptor of the second intron. The third intron was additionally spliced from a portion of these molecules; these mRNAs encoded the 14-kDa protein. A portion was not spliced further and encoded VP2. Like B19, SPV has a polyadenylation signal [AAUAAA (pA)p] in the middle of the genome, which directed efficient polyadenylation of both spliced and unspliced mRNAs (encoding a putative 10-kDa protein, analogous to the B19 7.5-kDa protein, and SPV NS1, respectively). The 14-kDa protein was localized to both in the nucleus and cytoplasm.

Parvovirus B19 capsid protein VP2 inhibits hematopoiesis in vitro and in vivo: implications for therapeutic use

OBJECTIVE

To evaluate the capacity of parvovirus B19 capsid protein VP2 to inhibit hematopoiesis in vitro and in vivo. If effective, a VP2-derived construct may have therapeutic and prophylactic utility in diseases associated to overproduction of hematopoietic cells.

METHODS

The effect on hematopoiesis in vitro of recombinant VP2, intact and enzymatically fragmented, was evaluated in a colony formation assay, using cells from fetal liver and macaque bone marrow. VP2 was also administered intravenously in macaques and hematological parameters as well as the ex vivo colony formation were assayed during a follow-up period of 33 days.

RESULTS

VP2 inhibited BFU-E colony formation by about 55%. CFU-GM and CFU-GEMM colony formation was also affected. Fragmented VP2 retained the inhibitory effect. The ex vivo colony-forming capacity of macaque bone marrow cells was lower in animals that received VP2 injections, and a drop in hematocrit values was noted in one animal.

CONCLUSION

VP2 has an inhibitory effect on hematopoiesis in vitro and in vivo. An active region within VP2 is implied, which would be a strong candidate for use as a medicament in diseases such as polycytemia vera.

The structure of human parvovirus B19

Human parvovirus B19 is the only parvovirus known to be a human pathogen. The structure of recombinant B19-like particles has been determined to approximately 3.5-A resolution by x-ray crystallography and, to our knowledge, represents the first near-atomic structure of an Erythrovirus. The polypeptide fold of the major capsid protein VP2 is a "jelly roll" with a beta-barrel motif similar to that found in many icosahedral viruses. The large loops connecting the strands of the beta-barrel form surface features that differentiate B19 from other parvoviruses. Although B19 VP2 has only 26% sequence identity to VP3 of adeno-associated virus, 72% of the C(alpha) atoms can be aligned structurally with a rms deviation of 1.8 A. Both viruses require an integrin as a coreceptor, and conserved surface features suggest a common receptor-binding region.

Identification of a nonconventional motif necessary for the nuclear import of the human parvovirus B19 major capsid protein (VP2)

Human parvovirus B19 replicates and encapsidates its genome in the nucleus of erythroid progenitors in vivo and in vitro. We wanted to understand the determinants necessary for the nuclear transport of the major coat protein, VP2, which makes up about 96% of the viral capsid proteins. A nonconsensus basic motif, KLGPRKATGRW, necessary for the nuclear localization of VP2 was identified and shown to be able to import reporter proteins into the nucleus. The sequence is conserved among the VP2 C-terminal region of erythroviruses. This newly identified sequence will facilitate the understanding of the replication of these viruses.

Genetic diversity within human erythroviruses: identification of three genotypes

B19 virus is a human virus belonging to the genus Erythrovirus: The genetic diversity among B19 virus isolates has been reported to be very low, with less than 2% nucleotide divergence in the whole genome sequence. We have previously reported the isolation of a human erythrovirus isolate, termed V9, whose sequence was markedly distinct (>11% nucleotide divergence) from that of B19 virus. To date, the V9 isolate remains the unique representative of a new variant in the genus Erythrovirus, and its taxonomic position is unclear. We report here the isolation of 11 V9-related viruses. A prospective study conducted in France between 1999 and 2001 indicates that V9-related viruses actually circulate at a significant frequency (11.4%) along with B19 viruses. Analysis of the nearly full-length genome sequence of one V9-related isolate (D91.1) indicates that the D91.1 sequence clusters together with but is notably distant from the V9 sequence (5.3% divergence) and is distantly related to B19 virus sequences (13.8 to 14.2% divergence). Additional phylogenetic analysis of partial sequences from the V9-related isolates combined with erythrovirus sequences available in GenBank indicates that the erythrovirus group is more diverse than thought previously and can be divided into three well-individualized genotypes, with B19 viruses corresponding to genotype 1 and V9-related viruses being distributed into genotypes 2 and 3.

Human parvovirus B19

Parvovirus B19 (B19) was discovered in 1974 and is the only member of the family Parvoviridae known to be pathogenic in humans. Despite the inability to propagate the virus in cell cultures, much has been learned about the pathophysiology of this virus, including the identification of the cellular receptor (P antigen), and the control of the virus by the immune system. B19 is widespread, and manifestations of infection vary with the immunologic and hematologic status of the host. In healthy immunocompetent individuals B19 is the cause of erythema infectiosum and, particularly in adults, acute symmetric polyarthropathy. Due to the tropism of B19 to erythroid progenitor cells, infection in individuals with an underlying hemolytic disorder causes transient aplastic crisis. In the immunocompromised host persistent B19 infection is manifested as pure red cell aplasia and chronic anemia. Likewise, the immature immune response of the fetus may render it susceptible to infection, leading to fetal death in utero, hydrops fetalis, or development of congenital anemia. B19 has also been suggested as the causative agent in a variety of clinical syndromes, but given the common nature, causality is often difficult to infer. Diagnosis is primarily based on detection of specific antibodies by enzyme-linked immunosorbent assay or detection of viral DNA by dot blot hybridization or PCR. Treatment of persistent infection with immunoglobulin reduces the viral load and results in a marked resolution of anemia. Vaccine phase I trials show promising results.

Current molecular epidemiology and human parvovirus B19 infection

Viruses evolve gradually through replication. Therefore, isolates of a virus species can have different genome sequences, albeit slightly, if isolates are epidemiologically unrelated. The difference in virus genome involves difference in virus functions and clinical manifestations of virus infection. Molecular epidemiology of virus infection is a relatively new field directed at infection in humans but not other animals. Analyses are based on genomic differences between virus strains with advances in methodology related to DNA analyses, progress is being made. Classification of virus strains, tracing of transmission of a strain, analyses of outbreaks (including nosocomial infection), and analyses of pathogenesis of virus infection in humans (a natural host) are given attention in molecular epidemiological studies. Human parvovirus B19 is a common human pathogen associated with a wide variety of diseases, including erythema infectiosum, aplastic crisis, hydrops fetalis, and arthritis. B19 is not propagatable in conventional cell lines, hence, molecular cloning of B19 DNA directly from clinical materials has to be done. Events concerning B19 infection were analyzed based on the concept of molecular epidemiology and studies proved to be productive to better understand the pathogenesis of B19 infection.

Evolutionary relationships among parvoviruses: virus-host coevolution among autonomous primate parvoviruses and links between adeno-associated and avian parvoviruses

The current classification of parvoviruses is based on virus host range and helper virus dependence, while little data on evolutionary relationships among viruses are available. We identified and analyzed 472 sequences of parvoviruses, among which there were (virtually) full-length genomes of all 41 viruses currently recognized as individual species within the family Parvoviridae. Our phylogenetic analysis of full-length genomes as well as open reading frames distinguished three evolutionary groups of parvoviruses from vertebrates: (i) the human helper-dependent adeno-associated virus (AAV) serotypes 1 to 6 and the autonomous avian parvoviruses; (ii) the bovine, chipmunk, and autonomous primate parvoviruses, including human viruses B19 and V9; and (iii) the parvoviruses from rodents (except for chipmunks), carnivores, and pigs. Each of these three evolutionary groups could be further subdivided, reflecting both virus-host coevolution and multiple cross-species transmissions in the evolutionary history of parvoviruses. No parvoviruses from invertebrates clustered with vertebrate parvoviruses. Our analysis provided evidence for negative selection among parvoviruses, the independent evolution of their genes, and recombination among parvoviruses from rodents. The topology of the phylogenetic tree of autonomous human and simian parvoviruses matched exactly the topology of the primate family tree, as based on the analysis of primate mitochondrial DNA. Viruses belonging to the AAV group were not evolutionarily linked to other primate parvoviruses but were linked to the parvoviruses of birds. The two lineages of human parvoviruses may have resulted from independent ancient zoonotic infections. Our results provide an argument for reclassification of Parvovirinae based on evolutionary relationships among viruses.