An outbreak of erythema infectiosum associated with human parvovirus infection

Detection of coinfection with Primate Erythroparvovirus 1 and arboviruses (DENV, CHIKV and ZIKV) in individuals with acute febrile illness in the state of Rio Grande do Norte in 2016

BACKGROUND

Arthropod-borne viruses, known as arboviruses, pose substantial risks to global public health. Dengue (DENV), Chikungunya (CHIKV) and Zika (ZIKV) viruses stand out as significant concerns in Brazil and worldwide. Their overlapping clinical manifestations make accurate diagnosis a challenge, underscoring the need for reliable laboratory support. This study employs a comprehensive molecular diagnostic approach to track viral infections in individuals with acute febrile illness, a period marked by widespread outbreaks of DENV, CHIKV and ZIKV.

METHODS

Between January and August 2016, we received a total of 713 serum samples obtained from individuals with acute febrile illness, previously tested for DENV, CHIKV or ZIKV, with initial negative results, from LACEN-NATAL. Of the total 713 samples, 667 were from females (354 of them pregnant) and 46 from males. Molecular diagnosis was conducted using the Multiplex RT-qPCR technique for simultaneous detection of DENV, CHIKV and ZIKV. Additionally, we performed differential diagnosis by RT-qPCR for other viruses of the Flavivirus, Alphavirus Enterovirus genera and qPCR for Primate Erythroparvovirus 1 (B19V) species, in accordance with Ministry of Health guidelines.

RESULTS

Among the 713 cases, 78.2% tested positive for viral infections, including 48% with CHIKV viremia, 0.6% with DENV and 0.1% with ZIKV. Arboviral coinfections totaled 2.4%, including DENV-CHIKV (1.7%) and CHIKV-ZIKV (0.7%). Moreover, 8% exhibited B19V viremia. Simultaneous infections were identified in 17.5%, encompassing B19V-CHIKV (17.1%), B19V-DENV (0.1%), and B19V-ZIKV (0.3%) Triple infections were observed in 1.3% of cases with B19V-DENV-CHIKV (1%) and B19V-CHIKV-ZIKV (0.3%).

CONCLUSION

Molecular testing demonstrated high efficacy in diagnosing prevalent arboviruses and detecting multiple coinfections. This approach helps to elucidate etiologies for symptomatic cases, especially during arbovirus outbreaks, and aids comprehensive surveillance. Our findings underscore the importance of monitoring co-circulating pathogens, such as B19V, with implications for clinical management, particularly in pregnant individuals. This study enhances our understanding of arbovirus epidemiology and reinforces the critical role of molecular diagnosis in disease surveillance and control.

The epidemiological and genetic characteristics of human parvovirus B19 in patients with febrile rash illnesses in China

To understand the epidemiological and genetic characteristics of B19V, a multiple-province surveillance of patients with febrile rash illnesses (FRIs) were conducted in China during 2009 ~ 2021. The clinical specimens of 3,820 FRI patients were collected and tested for B19V DNA. A total of 99 (2.59%) patients were positive for B19V, and 49 (49.49%) were children under 5 years old. B19V infections occurred throughout the year without obvious seasonal pattern. Ten NS1-VP1u sequences and seven genome sequences were obtained in this study, identified as subgenotype 1a. Combined with the globally representative genome sequences, no temporal and geographic clustering trends of B19V were observed, and there was no significant correlation between B19V sequences and clinical manifestations. The evolutionary rate of the B19V genome was 2.30 × 10-4 substitutions/site/year. The number of negative selection sites was higher than that of positive selection sites. It was the first to comprehensively describe the prevalence patterns and evolutionary characteristics of B19V in FRI patients in China. B19V played the role in FRI patients. Children under 5 years old were the main population of B19V infection. Subgenotype 1a was prevalent in FRI patients in China. B19V showed a high mutation rate, while negative selection acted on the genome.

Parvovirus B19 status in liver, kidney and pancreas transplant candidates: A single center experience

BACKGROUND

Parvovirus B19 (B19V) is associated with a wide range of clinical manifestations. The major presentation is erythema infectiosum. However, a persistent infection may cause pure red cell aplasia and chronic anemia in immunocompromized patients. The B19V seroprevalence varies with age and geographical location.

AIM

To determine the B19V serological status and DNAemia in kidney, liver, and pancreas transplant candidates.

METHODS

Patients who underwent kidney, liver, or simultaneous kidney and pancreas/liver transplantation between January 2021 and May 2022 were included in the study. The serum samples were collected before transplantation. For detection of B19V DNA, a LightMix Kit B19V EC (TIB MOLBIOL, Berlin, Germany) was used. B19V IgM and IgG antibodies were detected using a commercial ELISA test (Euroimmun, Lübeck, Germany).

RESULTS

One hundred and thirty-one transplant candidates were included in the study, 71.0% male, with an average age of 53.27 years ± 12.71 years. There were 68.7% liver, 27.5% kidney, 3.0% simultaneous pancreas/kidney transplant (SPKT), and 0.8% simultaneous liver/kidney transplant recipients. No patients had detectable B19V DNA. B19V IgG seroprevalence was 77.1%. No acute or recent infections were detected (IgM antibodies). There was no difference in the mean age of seronegative and seropositive patients (51.8 years ± 12.9 years vs 53.7 years ± 12.7 years, t = -0.603; P = 0.548). Although seropositivity was lower in patients aged less than 30 years (66.6%) compared to the patients aged 30-59 years and > 60 years (80.4% and 78.1%, respectively), this difference was not significant. In addition, there was no difference in seropositivity between male and female transplant candidates, 76.3% and 78.9% (χ² = 0.104; P = 0.748). The seroprevalence did not differ among organ recipients, with 77.8%, 80.6%, and 50.0% for liver, kidney, and SPKT, respectively, (χ² = 5.297; P = 0.151). No significant difference was found in the seroprevalence in kidney transplant patients according to dialysis modality. Seroprevalence was 71.1% in hemodialysis patients, and 100% in peritoneal dialysis patients (χ² = 0.799; P = 0.372).

CONCLUSION

The B19V seroprevalence is expectedly high among kidney, liver, and pancreas transplant candidates, but there are still 22.9% of seronegative individuals who remain at risk for primary disease and severe manifestations. Further research should elucidate the necessity of B19V screening in peri-transplant management.

The detection, treatment of parvovirus B19 infection induced anemia in solid organ transplants: a case series and literature review of 194 patients

BACKGROUND

There are no optimal diagnostic, treatment and post-infection surveillance strategies for parvovirus B19 infection in solid organ transplantation (SOT) recipients.

METHODS

We conducted a retrospective review of all PVB19 infected cases confirmed by qPCR among SOT recipients at our institution over a 3-year period and reviewed the literature from 1990 to 2021.

RESULTS

Eight kidney and two heart transplant patients with refractory anemia had PVB19 infection. The viral DNA load in peripheral blood ranged from 2.62 × 10² to 8.31 × 10⁶ copies/mL. Two patients with the lowest PVB19 DNA load only reduced the use of immunosuppressants and anemia was relieved. Eight received intravenous immunoglobulin (IVIG) (ranging from 0.25 to 0.5 g/kg/day). The median time to anemia improvement (hemoglobulin>100g/L) was 16 days (8-70 days) after treatment. One patient had a PVB19 relapse and viral DNA load > 1.00 × 10⁸ copies/mL at diagnosis. A total of 86 studies involving 194 SOTs were screened from the literature, and the most common symptom was anemia and low reticulocyte count. PVB19 DNA was detected in all cases. Of that, 91.4% of cases received IVIG, 53.8% received IVIG and immunosuppression reduction, 6.5% of cases showed reduced immunosuppression without IVIG, and 2.1% did not receive any special treatment. The recurrence rate was 17.5%.

CONCLUSION

PVB19 infection is a cause of anemia after SOT, and treatment mainly relies on IVIG and/or immunosuppression reduction.

Molecular-genetic characterization of human parvovirus B19 prevalent in Kerala State, India

Background

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.

Methods

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.

Results

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.

Conclusion

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.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12985-021-01569-1.

An Outbreak of Human Parvovirus B19 Hidden by Dengue Fever

BACKGROUND

Seasonal outbreaks of dengue often result in hundreds of dengue-suspected cases where a clinical diagnosis cannot be confirmed. Usually, during large outbreaks of dengue and other pathogens that can cause acute febrile illnesses, the search for secondary pathogens with similar disease outcomes is rare.

METHODS

Using total RNA sequencing and targeted diagnostic assays, we discovered an outbreak of parvovirus B19 in dengue-suspected patients that occurred from November 2013 to February 2014.

RESULTS

Of the 182 cases investigated, 63% were viremic for the B19 virus. Moreover, we found that >43% of infected patients had no serological evidence of prior infection. Parvovirus B19 is a typical childhood infection, yet we observed that 82% of the infected patients were adults. Additionally, we perceived that infected adults had significantly higher presentations of myalgia than in children. We also obtained viral protein (VP) 1/VP2 gene nucleotide sequences from 43 patients.

CONCLUSIONS

Our results support the utility of next-generation sequencing for symptomatic patients with unknown etiologies during seasonal outbreaks of dengue and other arborviruses. Our findings could improve the vigilance of hospitals and laboratories by raising awareness of co-circulating pathogens such as parvovirus B19 that may be hidden in plain sight.

Neurologic infections during pregnancy

Neurologic infections during pregnancy represent a significant cause of maternal and fetal morbidity and mortality. Immunologic alterations during pregnancy increase the susceptibility of the premature brain to damage. This chapter summarizes the epidemiology, pathophysiology, and clinical manifestations in the pregnant woman and the infant, and the diagnosis, treatment, and prevention of the major viral, parasitic, and bacterial infections known to affect pregnancy. These organisms include herpes virus, parvovirus, cytomegalovirus, varicella, rubella, Zika virus, toxoplasmosis, malaria, group B streptococcus, listeriosis, syphilis, and tuberculosis. There is an emphasis on the important differences in diagnosis, treatment, and fetal outcome between trimesters. An additional overview is provided on the spectrum of neurologic sequelae of an affected infant, which ranges from developmental delay to hydrocephalus and seizures.

First Report of Prevalence of Blood-Borne Viruses (HBV, HCV, HIV, HTLV-1 and Parvovirus B19) Among Hemophilia Patients in Afghanistan

Blood-borne viruses including Hepatitis B and C, HIV, HTLV-1 and parvovirus B19 are still a factor of concern, especially for hemophilia patients. Although the safety of the blood supply continues to improve worldwide, the blood supply system in Afghanistan was damaged by many years of conflict and political instability. To date, there are few studies focused on the prevalence of blood-borne viruses in hemophilia patients. This study is first to investigate the prevalence of five blood-borne viruses in Afghanistan hemophilia patients in four cities including Kabul, Herat, Mazar-i-Sharif and Jalal Abad. A total of 80 hemophilia male patients were screening for the presence of five transfusion-transmitted viruses using ELISA and PCR. Data obtained showed 2.5% seropositivity for HBV, 8.75% seropositivity for HCV, and 91.25% seropositivity for parvovirus B19. None of the patients were positive for HIV and HTLV-1 and the prevalence of HCV was higher in older patients rather than younger patients. This finding, the first to report in Afghanistan, shows a high prevalence of parvovirus B19 in Afghanistan hemophilia patients and implementation of highly sensitive screening is necessary.

Structure of Parvovirus B19 Decorated by Fabs from a Human Antibody

Parvovirus B19, one of the most common human pathogens, is a small DNA virus that belongs to the Parvoviridae As a result of previous infections, antibodies to B19 are present in most adults. B19 has a strong tropism to erythroid progenitor cells and is able to cause a series of medical conditions, including fifth disease, arthritis, myocarditis, hydrops fetalis, and aplastic crisis. No approved vaccine is currently available for B19, and there is a lack of structural characterization of any B19 epitopes. Here we present the first cryo-electron microscopy (cryo-EM) structure of a B19 virus-like particle (VLP) complexed with the antigen-binding fragment (Fab) of a human neutralizing antibody, 860-55D. A model was built into the 3.2-Å-resolution map, and the antigenic residues on the surface of the B19 capsid were identified. Antibody 860-55D bridges the capsid of B19 by binding to a quaternary structure epitope formed by residues from three neighboring VP2 capsid proteins.IMPORTANCE Parvovirus B19 is a common human pathogen and a particular threat to children, pregnant women, and patients with sickle cell disease or AIDS. Currently, neutralizing antibody is the most efficient treatment for acute B19 infections. Research on the antigenic properties of B19 will guide the usage of these antibodies and facilitate vaccine development. We have determined and report here the high-resolution structure of B19 virus-like particles (VLPs) complexed with the Fab of a human neutralizing antibody. The structure shows a quaternary structure epitope formed by three VP2 proteins and provides details on host recognition of human B19 virus.

Human parvovirus B19 in solid organ transplantation: Guidelines from the American society of transplantation infectious diseases community of practice

Clinical manifestations of human parvovirus B19 infection can vary widely and may be atypical in solid organ transplant (SOT) recipients. However, disease is apparent when there is destruction of erythrocyte progenitor cells leading to severe acute or chronic anemia with lack of an appropriate reticulocyte response in the setting of active parvovirus B19 infection. Serology may not reliably establish the diagnosis. High-level viremia is more likely to be associated with symptomatic disease. Conversely, ongoing DNAemia after infection may not be clinically significant, if detected at low levels. Despite lack of robust data, intravenous immunoglobulin (IVIG) is frequently used for the treatment of SOT recipients with symptomatic parvovirus B19 infection. Although the optimal dosage and duration of IVIG is not known, most patients receive a total of 2 g/kg over a period of 2-5 days. A daily dose of 1 g/kg or more seems to be associated with higher incidence of toxicity. Application of standard and droplet isolation precautions remains the cornerstone for preventing human parvovirus B19 transmission. Additional research is needed to assess the efficacy of current and novel therapies and to develop a safe and effective parvovirus B19 vaccine.

Detection of Viral RNA Splicing in Diagnostic Virology

This chapter is the first one to introduce the detection of viral RNA splicing as a new tool for clinical diagnosis of virus infections. These include various infections caused by influenza viruses, human immunodeficiency viruses (HIV), human T-cell leukemia viruses (HTLV), Torque teno viruses (TTV), parvoviruses, adenoviruses, hepatitis B virus, polyomaviruses, herpesviruses, and papillomaviruses. Detection of viral RNA splicing for active viral gene expression in a clinical sample is a nucleic acid-based detection. The interpretation of the detected viral RNA splicing results is straightforward without concern for carry-over DNA contamination, because the spliced RNA is smaller than its corresponding DNA template.

Although many methods can be used, a simple method to detect viral RNA splicing is reverse transcription-polymerase chain reaction (RT-PCR). In principle, the detection of spliced RNA transcripts by RT-PCR depends on amplicon selection and primer design. The most common approach is the amplification over the intron regions by a set of primers in flanking exons. A larger product than the predicted size of smaller, spliced RNA is in general an unspliced RNA or contaminating viral genomic DNA. A spliced mRNA always gives a smaller RT-PCR product than its unspliced RNA due to removal of intron sequences by RNA splicing. The contaminating viral DNA can be determined by a minus RT amplification (PCR). Alternatively, specific amplification of a spliced RNA can be obtained by using an exon-exon junction primer because the sequence at exon-exon junction is not present in the unspliced RNA nor in viral genomic DNA.

Parvovirus B19 infection during pregnancy and risks to the fetus

Parvovirus B19 infects 1 to 5% of pregnant women, generally with normal pregnancy outcomes. During epidemics, the rate of infection is higher. Major congenital anomalies among offspring of infected mothers are rare, as the virus does not appear to be a significant teratogen. However, parvovirus B19 infection may cause significant fetal damage, and in rare cases, brain anomalies and neurodevelopmental insults, especially if infection occurs in the first 20 weeks of pregnancy. Parvovirus B19 is also an important cause of fetal loss, especially in the second half of pregnancy when spontaneous fetal loss from other causes is relatively rare. Parvovirus B19 infection may affect many fetal organs and can cause severe anemia, following fetal erythroid progenitor cells infection and apoptosis, especially in fetuses, that have shortened half-life of erythrocytes. Severe anemia may cause high output cardiac failure and nonimmune hydrops fetalis. In addition, parvovirus B19 may directly infect myocardial cells and produce myocarditis that further aggravates the cardiac failure. Intrauterine fetal transfusion is commonly used for the treatment of severe fetal anemia with survival rates of 75 to 90% and significant reduction of fetal morbidity. Only 66 cases were evaluated neurodevelopmentally, of which 10 (16%) had slight or severe neurodevelopmental problems. Because parvovirus B19 infection can cause severe fetal morbidity and mortality, it should be part of the routine work-up of pregnant women who have been exposed to the virus or of pregnancies with suspected fetal hydrops. Assessment for maternal infection during pregnancy is especially important during epidemics, when sero-conversion rates are high. Birth Defects Research 109:311-323, 2017. © 2017 Wiley Periodicals, Inc.

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.

Parvovirus B19 infection in pregnancy-awareness and opportunities

Parvovirus B19 (B19V) is a human pathogenic virus associated with a wide range of clinical conditions. In pregnancy, B19V poses a potential hazard to the fetus as crossing the placental barrier and infecting erythroid progenitor cells in bone marrow and liver, it blocks fetal erythropoiesis leading to profound anemia, hydrops and/or fetal death. The virus is not regarded as a teratogen, however more scientific awareness is emerging on mechanisms and consequences of intrauterine infection and possible sequelae in the neonatal development. Reliable diagnostic procedures and fetal management strategies, including intrauterine transfusion, are established. In spite of being a recognized fetotropic agent possibly leading to fetal loss, testing for B19V is not routinely included in preconception or antenatal screenings, possibly delaying the management of B19V-complicated pregnancies. Continuous advances in B19V research will provide for better diagnostic methods and algorithms, as well as for the development of effective prophylactic interventions and novel therapeutic options.

The determinants for the enzyme activity of human parvovirus B19 phospholipase A2 (PLA2) and its influence on cultured cells

Human parvovirus B19 (B19V) is the causative agent of erythema infectiosum in humans. B19 infection also causes severe disease manifestations, such as chronic anemia in immunocompromised patients, aplastic crisis in patients with a high turnover rate of red blood cells, and hydrops fetalis in pregnant women. Although a secreted phospholipase A2 (PLA2) motif has been identified in the unique region of the B19V minor capsid protein VP1(VP1u), the determinants for its enzyme activity and its influences on host cells are not well understood. The purpose of this study was to investigate the contribution of the PLA2 motif and other regions of the VP1u to the PLA2 activity, to determine the cellular localization of the VP1u protein, and to examine the effects of VP1u on cellular cytokines. We found that in addition to the critical conserved and non-conserved amino acids within the VP1u PLA2 motif, amino acid residues outside the VP1u PLA2 motif are also important for the PLA2 activity. VP1u and various mutants all revealed a nucleo-cytoplasmic distribution. UT7-Epo cells treated with prokaryotic expressed VP1u or mutant proteins with PLA2 activity released a large amount of free fatty acid (FFA), and the cell morphological change occurred dramatically. However, neither free fatty acid nor cell morphology change occurred for cells treated with the mutants without PLA2 activity. The wild type and the VP1u mutants with the PLA2 activity also activated TNF-α promoter and upregulated the transcription activity of NF-κB in transfected cells. In addition, we found that the amino acids outside the PLA2 domain are critical for the viral PLA2 activity, and that these tested VP1u mutants did not affect the localization of the VP1u protein.

Parvovirus transmission by blood products - a cause for concern?

The introduction of dual viral inactivation of clotting factor concentrates has practically eliminated infections by viruses associated with significant pathogenicity over the last 20 years. Despite this, theoretical concerns about transmission of infection have remained, as it is known that currently available viral inactivation methods are unable to eliminate parvovirus B19 or prions from these products. Recently, concern has been raised following the identification of the new parvoviruses, human parvovirus 4 (PARV4) and new genotypes of parvovirus B19, in blood products. Parvoviruses do not cause chronic pathogenicity similar to human immunodeficiency virus or hepatitis C virus, but nevertheless may cause clinical manifestations, especially in immunosuppressed patients. Manufacturers should institute measures, such as minipool polymerase chain reaction testing, to ensure that their products contain no known viruses. So far, human bocavirus, another new genus of parvovirus, has not been detected in fractionated blood products, and unless their presence can be demonstrated, routine testing during manufacture is not essential. Continued surveillance of the patients and of the safety of blood products remains an important ongoing issue.

Seroprevalence of immunoglobulin G antibody to parvovirus B19 in Ontario

The prevalence of antibody to parvovirus B19 was assessed in two populations. In a group of 494 residents from Ontario and the Maritimes, virus-specific immunoglobulin (Ig) M antibody, a marker of acute infection, was found throughout the year but was most prevalent during the late winter and early spring months. The overall prevalence of IgG antibody in this group was 30.3%. In an effort to examine age-specific prevalence in this population, a second group of sera from 210 pediatric patients at The Hospital for Sick Children, Toronto, Ontario and from Red Cross blood donors was tested for the presence of B19-specific IgG, and of these, 31.4% of the samples were positive. This prevalence varied from 3.3% in the under five-year-old age group to 66.7% in the 35- to 45-year-old age group. Eighty per cent of sera from females of this group were seropositive. This study provides insight into the prevalence of parvovirus B19 IgG antibody in the population.

Acute diarrhea in West African children: diverse enteric viruses and a novel parvovirus genus

Parvoviruses cause a variety of mild to severe symptoms or asymptomatic infections in humans and animals. During a viral metagenomic analysis of feces from children with acute diarrhea in Burkina Faso, we identified in decreasing prevalence nucleic acids from anelloviruses, dependoviruses, sapoviruses, enteroviruses, bocaviruses, noroviruses, adenoviruses, parechoviruses, rotaviruses, cosavirus, astroviruses, and hepatitis B virus. Sequences from a highly divergent parvovirus, provisionally called bufavirus, were also detected whose NS1 and VP1 proteins showed <39% and <31% identities to those of previously known parvoviruses. Four percent of the fecal samples were PCR positive for this new parvovirus, including a related bufavirus species showing only 72% identity in VP1. The high degree of genetic divergence of these related genomes from those of other parvoviruses indicates the presence of a proposed new Parvoviridae genus containing at least two species. Studies of the tropism and pathogenicity of these novel parvoviruses will be facilitated by the availability of their genome sequences.

Diagnosis, management and possibilities to prevent parvovirus B19 infection in pregnancy

Human parvovirus B19 (B19V) infection in pregnancy can cause severe fetal anemia and nonimmune hydrops fetalis, which may be associated with spontaneous abortion and fetal death. Approximately 30–40% of women of child-bearing age are not immune to B19V infection. The risk to fetal life is particularly high if maternal infection occurs during the first 20 weeks of gestation. In this article we intend to give an overview on the molecular biology, epidemiology and management of B19V infection during pregnancy. These data will be combined with an assessment of the clinical situation of the infected fetus and the possibilities for avoiding and/or preventing B19V infection in pregnant women. Currently B19V infection is the causative agent of one of the most frequently occurring infectious complications in pregnancy that endangers fetal life, and so the necessity to develop a preventive vaccine is discussed.

Parvovirus B19 infection in human pregnancy

Human parvovirus B19 infection is widespread. Approximately 30-50% of pregnant women are nonimmune, and vertical transmission is common following maternal infection in pregnancy. Fetal infection may be associated with a normal outcome, but fetal death may also occur without ultrasound evidence of infectious sequelae. B19 infection should be considered in any case of nonimmune hydrops. Diagnosis is mainly through serology and polymerase chain reaction. Surveillance requires sequential ultrasound and Doppler screening for signs of fetal anaemia, heart failure and hydrops. Immunoglobulins, antiviral and vaccination are not yet available, but intrauterine transfusion in selected cases can be life saving.

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.

Parvovirus B19: its role in chronic arthritis

B19 infection-associated joint symptoms occur most frequently in adults, usually presenting as a self-limited, acute symmetric polyarthritis affecting the small joints of the hands, wrists, and knees. A small percentage of patients persist with chronic polyarthritis that mimics rheumatoid arthritis raising the question of whether B19 virus may have a role as a concomitant or precipitating factor in the pathogenesis of autoimmune conditions. Comprehensive and updated reviews address different aspects of human parvovirus infection. This article focuses on the evidence supporting the arthritogenic potential of the B19 virus and the proposed mechanisms that underlie it.

Red baby syndrome a new disease due to parvovirus B-19 observed in Kerala

Red Baby Syndrome is a new disease seen in infants and young children. Dramatic onset of clinical symptoms with high intensity, short duration and lack of similarity with other cutaneous lesions makes it distinct. Of 50 such patients studied over a period of 5 years, half were below one year of age. Abrupt onset of high fever and generalized erythema involving the entire skin, which is swollen and tender is characteristic. These children were highly irritable and had paradoxical cry when cuddled. Rapid resolution of symptoms occurred in 7-10 days with extensive desquamation. Routine investigations were normal, C-reactive protein was raised only in 10 patients. Human Parvo virus B-19 IgM antibodies were positive in 15 out of 24 patients. Real time polymerase chain reaction was positive for human parvovirus B 19 DNA in one. Histopathological changes in the skin biopsy showed post infectious vascular injury pattern.

Adaptive immune responses against parvovirus B19 in patients with myocardial disease

BACKGROUND

Parvovirus B19 (B19V)-DNA is frequently detected in endomyocardial biopsies (EMBs) from patients with acute myocarditis (AMC) and dilated cardiomyopathy (DCM), but also in various healthy tissues. The clinical relevance of this DNA-persistence is unclear.

OBJECTIVES

To investigate potential pathogenic influences of B19V-DNA in EMBs, we analyzed B19V-specific adaptive immune responses in AMC/DCM patients and healthy controls.

STUDY DESIGN

15 AMC/DCM patients with detectable B19V-DNA in EMBs and 51 controls were analyzed for signs of acute B19V-infections and virus-specific immune responses by PCR, ELISA, Western line, and ELISpot-assays.

RESULTS

Productive B19V-infection was determined in three patients. Slightly lower levels of B19V-specific T-cells were observed in patients as compared to the controls, no differences were observed in virus-specific serology. Viral DNA-load in EMBs could not be correlated to the number of B19V-specific T-cells. No differences in T-cell response, viremia and/or serological markers indicative for viral pathogenesis were observed in patients with inflammatory cardiomyopathy.

CONCLUSIONS

Discrepancies in B19V-specific adaptive immunity were not observed in AMC/DCM patients as compared to controls. The data indicate that the exclusive detection of B19V-DNA in EMBs is not sufficient to associate B19V with AMC/DCM but should be complemented with additional virological and immunological parameters in further studies.

Clinical and epidemiological aspects of human bocavirus infection

Human bocavirus was recently described as a novel member of the Parvoviridae to infect humans. Based on accumulating clinical and epidemiological data the virus is currently being associated with respiratory infections in young children and infants and is furthermore discussed as causative agent of gastrointestinal illness.

Seroepidemiology of human bocavirus defined using recombinant virus-like particles

BACKGROUND

Human bocavirus (HBoV) is a newly identified human parvovirus for which seroepidemiology and antigenic properties remain undefined.

METHODS

The HBoV VP2 gene, expressed from a baculovirus vector, produced virus-like particles (VLPs), which were used to raise rabbit anti-HBoV antisera and to develop an enzyme-linked immunosorbent assay (ELISA). The VLP-based ELISA was used to screen for HBoV-specific immunoglobulin G antibodies in a convenience sample of 270 serum specimens, mostly from children, obtained at Yale-New Haven Hospital; 208 specimens were also screened for erythrovirus B19-specific antibodies by a B19 VLP-based ELISA.

RESULTS

Immunofluorescence and ELISA showed that human parvoviruses HBoV and B19 are antigenically distinct. By the HBoV VLP-based ELISA, 91.8% and 63.6% of serum specimens from infants in the first and second months of life, respectively, were found to be seropositive, as were 45.4% from 3-month-old infants and 25.0% from 4-month-old infants. The percentages of HBoV-seropositive children increased to 40.7%-60.0% for children 5-47 months of age and to >85% for individuals >or=48 months old. However, the overall percentage of B19-seropositive individuals was <40.5% for all age groups screened.

CONCLUSIONS

HBoV infection is common during childhood, but a minority of children and young adults screened have evidence of B19 infection.

[Viral infections of the fetus and newborn infant]

Viral infections may be vertically transmitted from mother to child at different times, ranging from in utero transmission, which occurs during pregnancy, perinatal transmission, which takes place during delivery and postnatal transmission, which is usually the consequence of breastfeeding. Mother-to-child transmission, which may occur after primary, recurrent or chronic maternal infection, is potentially harmful to the fetus or the newborn since it may result in miscarriage, fetal death, congenital anomalies, intrauterine growth restriction, or severe neonatal disease. Some risk factors are thought to affect the rate of mother-to-child transmission, such as the presence of other viral infections, maternal viral load, type of infection (primary versus recurrent), obstetrical procedures (prolonged rupture of membranes, mode of delivery), social-economical conditions and breastfeeding. For some of the vertically transmitted viruses, interventions are nowadays available to prevent mother-to-child transmission, such as vaccines, passive immunization, antiviral drugs. Moreover, perinatal and postnatal infections may be prevented by the use of elective caesarean delivery and avoidance of breastfeeding.

Parvovirus B19 infection in Chile: markers of infection and immunity in patients with clinical symptoms

Parvovirus B19 infection is associated with a wide variety of symptoms and signs, and given that some clinical features, such as anemia, arthropathy and rash may be attributable to other causes, laboratory diagnosis of B19 markers is necessary. The principal aims were to study the behavior of B19 infection-associated diseases in the Chilean population and to compare B19 markers for recent or active infection and for immunity status in patients with clinical symptoms suspicious of B19 infection and control individuals. Sera from a total of 267 patients with diverse clinical manifestations associated with B19 and from 69 healthy controls were tested for B19 DNA using PCR and for specific IgM and immunoglobulin G (IgG) by enzyme-linked immunosorbent assay (ELISA). Out of 267 patients examined, 89 had B19-associated disease markers: 43 had B19 DNA without IgM, 25 had IgM without B19 DNA, and 21 had both B19 DNA and IgM. Also 49 patients were positive only for IgG without B19 DNA or IgM. Out of the 69 healthy controls, only 2 had B19 DNA without IgM and 30 had IgG without B19 DNA and/or IgM. The distribution of the clinical diagnoses associated with recent B19 infection, tested by B19 DNA and/or IgM, included 38.5% with hematological illnesses, 23.4% with rheumatic diseases, 45.7% with infectious diseases, 33.3% with indications of prenatal infection, 32.3% with conditions that induce immunodeficiency, and 15.8% with other miscellaneous conditions. The use of both markers, DNA and IgM, allows a more adequate diagnosis of infection by this virus.

Tissue persistence and prevalence of B19 virus types 1–3

Human parvovirus B19 is a minute ssDNA virus that causes a wide variety of diseases, including erythema infectiosum, arthropathy, anemias and fetal death. In addition to the B19 prototype, two new variants (B19 types 2 and 3) have been identified. After primary infection, B19 genomic DNA has been shown to persist in solid tissues of not only symptomatic but also of constitutionally healthy, immunocompetent individuals. The viral DNA persists as an intact molecule without persistence-specific mutations, and via a storage mechanism with life-long capacity. Thus, the mere presence of B19 DNA in tissue cannot be used as a diagnostic criterion, although a possible role in the pathology of diseases, for example through mRNA or protein production, cannot be excluded. The molecular mechanism, host-cell type and possible clinical significance of tissue persistence are yet to be elucidated.

Biological and immunological relations among human parvovirus B19 genotypes 1 to 3

The human parvovirus B19 is now divided into three genotypes: type 1 (prototype), type 2 (A6- and LaLi-like), and type 3 (V9-like). In overall DNA sequence, the three virus types differ by approximately 10%. The most striking DNA dissimilarity, of >20%, is observed within the p6 promoter region. Because of the scarcity of data on the biological activities and pathogenetic potentials of virus types 2 and 3, we examined the functional characteristics of these virus types. We found the activities of the three p6 promoters to be of equal strength and to be most active in B19-permissive cells. Virus type 2 capsid protein VP2, alone or together with VP1, was expressed with the baculovirus system and was shown to assemble into icosahedral parvovirus-like particles, which were reactive in the hemagglutination assay. Furthermore, sera containing DNA of any of the three B19 types were shown to hemagglutinate. The infectivities of these sera were examined in two B19-permissive cell lines. Reverse transcription-PCR revealed synthesis of spliced B19 mRNAs, and immunofluorescence verified the production of NS and VP proteins in the infected cells. All three genotypes showed similar functional characteristics in all experiments performed, showing that the three virus types indeed belong to the same species, i.e., human parvovirus B19. Additionally, the antibody activity in sera from B19 type 1- or type 2-infected subjects (long-term immunity) was examined with homo- and heterologous virus-like particles. Cross-reactivity of 100% was observed, indicating that the two B19 genotypes comprise a single serotype.

Parvovirus B19 detected in Rosai-Dorfman disease in nodal and extranodal manifestations

Sinus histiocytosis with massive lymphadenopathy (SHML), also designated as Rosai-Dorfman disease (RDD), is a rare benign reactive lymphoproliferative disorder. It is defined by a characteristic histopathology with sinus histiocytosis and haemophagocytosis known as emperipolesis. In histiocytes S100 is strongly expressed, whereas CD1a staining typically is negative. The disease mainly manifests at a single lymph node; however, multilocular and extranodal affection can occur. Causative infectious agents, and virus infections in particular, have repeatedly been suspected, although until now the origin of the disease has been unclear. Four cases of RDD (two nodal sites and two extranodal upper respiratory tract sites) were analysed for parvovirus B19 (B19) infection by immunohistochemistry to detect B19 capsid proteins VP1/VP2. In all the four cases, huge numbers of B19-positive cells were partly detected. The positive cells were identified either as lymphocytes or, in one extranodal case, also as respiratory epithelial cells. This is the first report of B19 infection in RDD tissue, indicating that B19 may be associated with the pathogenesis of SHML.

Parvovirus B19 infection after transplantation: a review of 98 cases

BACKGROUND

Infections with parvovirus B19 (PVB19) can cause significant morbidity in transplant recipients.

METHODS

To characterize the epidemiology and clinical spectrum of posttransplant PVB19 infection, we reviewed all cases at our institution during a 16-year period, summarized the data from 91 cases published in the medical literature, and performed longitudinal molecular surveillance for PVB19 DNAemia among 47 solid organ and hematopoietic stem cell transplant recipients.

RESULTS

The median time to onset of PVB19 disease was 7 weeks after transplantation. Anemia, leukopenia, and thrombocytopenia were present in 98.8%, 37.5%, and 21.0% of patients, respectively. Hepatitis, myocarditis, and pneumonitis were also reported in association with PVB19 disease. Allograft tissue loss or dysfunction was observed at the time of PVB19 disease in 10% of cases. At the onset of disease, PVB19 IgM serological test results were negative in 29% of cases. Almost all patients (96%) with anti-PVB19 IgM had a positive PVB19 polymerase chain reaction assay result. Intravenous immunoglobulin was the most commonly used treatment modality. Three of 98 patients died of myocarditis and cardiogenic shock associated with PVB19 disease. Molecular surveillance throughout the first year after transplantation did not reveal PVB19 DNAemia in 47 anemic solid organ and hematopoietic stem cell transplant patients.

CONCLUSIONS

PVB19 is a rare but clinically significant infection that manifests as refractory anemia during the posttransplantation period. The use of polymerase chain reaction for diagnosis is particularly helpful in immunosuppressed transplant patients who may fail to mount antibodies against PVB19 during active infection.

Genetic drift of parvovirus B19 is found in AIDS patients with persistent B19 infection

It is generally thought that parvovirus B19 is stable genetically. Consistently, genetic drift has not been found in patients with persistent B19 infection. In this report, longitudinal genetic changes in NS1 and VP1 gene of B19 isolates from three AIDS patients with persistent B19 infection were studied. One of the three patients was not treated with highly active anti-retroviral therapy (HAART). B19 viral DNA from these patients was amplified by polymerase chain reaction (PCR) and then sequenced directly. A single genetic change was found in the B19 isolate obtained from the patient not treated with HAART on Day 10 after intravenous immunoglobulin (IVIG) treatment. The nucleotide sequences of B19 isolated from this patient, then remained unchanged over a period of 11 months. Analysis of NS1 clones derived from his longitudinal viral isolates showed the existence of quasi-species but genetic drift was not found. One of the other two patients treated with HAART experienced treatment failure; he was later treated with mega-HAART. In contrast to the genetic stability of B19 isolates from the patient not treated with HAART, multiple genetic changes were discovered in the viral isolates from the two other patients after HAART and mega-HAART, respectively. Through analysis of B19 clones, the frequency of clones containing these mutations confirmed the genetic drift. Nucleotide substitutions seen in VP2 gene of isolates with genetic drift from both patients were all non-conserved, suggesting that they are positively selected.

T helper cell-mediated interferon-gamma expression after human parvovirus B19 infection: persisting VP2-specific and transient VP1u-specific activity

Human parvovirus B19 is a small non-enveloped DNA virus with an icosahedral capsid consisting of proteins of only two species, the major protein VP2 and the minor protein VP1. VP2 is contained within VP1, which has an additional unique portion (VP1u) of 227 amino acids. We determined the ability of eukaryotically expressed parvovirus B19 virus-like particles consisting of VP1 and VP2 in the ratio recommended for vaccine use, or of VP2 alone, to stimulate, in an HLA class II restricted manner, peripheral blood mononuclear cells (PBMC) to proliferate and to secrete interferon gamma (IFN-gamma) and interleukin (IL)-10 cytokines among recently and remotely B19 infected subjects. PBMC reactivity with VP1u was determined specifically with a prokaryotically expressed VP1u antigen. In general, B19-specific IFN-gamma responses were stronger than IL-10 responses in both recent and remote infection; however, IL-10 responses were readily detectable among both groups, with the exception of patients with relapsed or persisting symptoms who showed strikingly low IL-10 responses. Whereas VP1u-specific IFN-gamma responses were very strong among the recently infected subjects, the VP1u-specific IFN-gamma and IL-10 responses were virtually absent among the remotely infected subjects. The disappearance of VP1u-specific IFN-gamma expression is surprising, as B-cell immunity against VP1u is well maintained.

Human parvovirus B19 experimental infection in human fibroblasts and endothelial cells cultures

With the aim to detect what kind of cells, in addition to erythroid progenitors, could be involved in the pathogenesis of B19 infection in some connective tissue diseases, primary cultures of human fibroblasts (HF) and endothelial cells (HUVEC) were exposed to a B19 positive serum (350 genome copies/cell). The presence of NS1 and VP1 mRNA, in both HF and HUVEC cultures 1, 2 and 6 days after the exposure, indicated infection by B19 virus. However, no significant increase of B19 DNA level in the infected HF and HUVEC cultures was detectable through the entire incubation period of 6 days. It is possible that HF and HUVEC are not permissive for B19 virus replication or, alternatively, that few cells only get infected by B19 virus. HF and HUVEC stimulation with different growth factors or cytokines could be required for a B19 productive infection to occur.

CD4+ T-Cell Responses Against the VP1-Unique Region in Individuals with Recent and Persistent Parvovirus B19 Infection

To date cellular immune responses against parvovirus B19 (B19) have not been studied extensively. The aim of this study was to examine the T-cell response against the VP1-unique region as the immunodominant part of the viral structural protein VP1 in individuals with different courses of B19 infection. Therefore, a group of 13 parvovirus-positive probands was separated into subgroups characterized for recent or acute, past or persistent infection by means of the presence of specific immunoglobulin (Ig)M and IgG isotypes and of viral DNA in blood and tissue. Transiently transfected B-cells expressing VP1-unique region were used in ELISpot assays to investigate T-cell responses directed against the VP1-unique region in peripheral blood mononuclear cells (PBMC) of individual donors. Significant numbers of interferon-gamma (IFN-gamma) secreting lymphocytes were detectable in PBMC of all individuals with recent, acute or persistent B19 infection, but not in PBMC of donors with past B19 infection and seronegative individuals. A more detailed analysis of IFN-gamma producing cells by intracellular cytokine staining by flow cytometry revealed, that CD4(+) T cells but not CD8(+) cytotoxic lymphocytes (CTL) were the major subpopulation of IFN-gamma producing cells. These data strongly suggest the need of virus protein production for the maintenance of VP1-unique region-specific CD4(+) T-helper cell responses in B19-infected individuals.

IgG subclass response to human parvovirus B19 infection

BACKGROUND

IgG antibodies are essential to immunity against human parvovirus B19 and can neutralize infection both in bone marrow cell cultures infected in vitro and in chronically infected immunosuppressed individuals.

OBJECTIVES

To assess the levels and response kinetics of IgG subclasses towards individual structural proteins of human parvovirus B19.

STUDY DESIGN

Subclasses of IgG for capsid proteins VP1 or VP2 were quantified by EIA using monoclonal antibodies in 30 acutely infected and 30 convalescent patients, as well as in 32 remotely infected and 20 non-infected controls.

RESULTS

In all groups of seropositive individuals the predominant subclass for either structural protein was IgG1. Subclass IgG3 was associated with acute infection. By contrast, IgG4 appeared months after infection, and occurred specifically towards VP1. The ratio of VP1-specific subclasses IgG3 and IgG4 provided a diagnostic test for recent infection with a specificity of 98% and a sensitivity of 97%.

CONCLUSIONS

Comparative measurement of VP1-specific IgG3 and IgG4 is useful in diagnosis. The IgG4 results point to long-term expression of immunologically active VP1 and to T-cell help of T(h)2 type for B-cells recognizing VP1.

Persistent parvovirus-associated chronic fatigue treated with high dose intravenous immunoglobulin

We report a 16-year-old boy with no evidence of immunodeficiency who had a 2-year history of chronic fatigue, low grade fever and slapped-cheek rash associated with chronic parvovirus B19 viremia. Prolonged intravenous immunoglobulin therapy resulted in resolution of his symptoms and viremia. Intravenous immunoglobulin may be useful in the resolution of parvovirus viremia regardless of immune status.

Seroprevalence, incidence of prenatal infections and reliability of maternal history of varicella zoster virus, cytomegalovirus, herpes simplex virus and parvovirus B19 infection in South-Western Finland

OBJECTIVE

To study seroprevalence and incidence and fetal transmission of varicella zoster virus (VZV), cytomegalovirus (CMV), herpes simplex virus (HSV) types 1 and 2 and parvovirus B19 infections during pregnancy and to evaluate the reliability of maternal past history of VZV, HSV and parvovirus infections.

DESIGN

Prospective study of parturient women.

SETTING

South-Western Finland.

PARTICIPANTS

Five hundred and fifty-eight parturient women.

METHODS

IgG and IgM antibodies against VZV, CMV, HSV-1 and -2, and parvovirus B19 were measured from maternal serum in the first trimester and at delivery and from cord serum, mother's own information of her past infections was compared with her serological status.

MAIN OUTCOME MEASURES

Seroprevalence, seroconversions and fetal transmission of VZV, CMV, HSV and parvovirus B19, reliability of maternal history of VZV, HSV and parvovirus B19.

RESULTS

Seroprevalences were 96.2% for VZV, 56.3% for CMV, 54.3% for HSV, 46.8% for HSV-1, 9.3% for HSV-2 and 58.6% for parvovirus B19. Parity was associated with CMV seropositivity, maternal age differed only between HSV-2 seropositive and seronegative women, while area of residence (urban or rural) had no effect. Six seroconversions were observed: two VZV, one CMV and three parvovirus infections. No cases of primary HSV infections occurred. Fetal transmission was observed in two cases of parvovirus infection. No infants with anti-CMV IgM antibodies were born to CMV immunised women. False positive history of chickenpox was given only by 1.5% of the women, history of herpes infections was less reliable, and history of parvovirus infection was unreliable.

CONCLUSIONS

Seroprevalence and the risk of viral infections during pregnancy cannot be extrapolated from one pregnant population to another.