The immature and suppressed immune response makes transplanted children a special susceptible group to Parvovirus B19 (PVB19). However, the clinical features of transplanted children with PVB19 infection haven\'t been comprehensively described.
We searched the medical records of all the transplant recipients who attended the Children\'s Hospital of Fudan University from 1 Oct 2020 to 31 May 2023, and reviewed the medical literature for PVB19 infection cases among transplanted children.
A total of 10 cases of PVB19 infection were identified in 201 transplanted children at our hospital, and the medical records of each of these cases were shown. Also, we retrieved 40 cases of PVB19 infection among transplanted children from the literature, thus summarizing a total of 50 unique cases of PVB19 infection. The median time to the first positive PVB19 DNA detection was 14 weeks post-transplantation. PVB19 IgM and IgG were detected in merely 26% and 24% of the children, respectively. The incidence of graft loss/dysfunction was as high as 36%. Hematopoietic stem cell transplant (HSCT) recipients showed higher PVB19 load, lower HGB level, greater platelet damage, lower PVB19 IgM/IgG positive rates, and more graft dysfunction than solid-organ transplant (SOT) recipients, indicating a more incompetent immune system.
Compared with the published data of transplanted adults, transplanted children displayed distinct clinical features upon PVB19 infection, including lower PVB19 IgM/IgG positive rates, more graft dysfunction, and broader damage on hematopoietic cell lines, which was even more prominent in HSCT recipients, thus should be of greater concern.

BACKGROUND: Erythema infectiosum occurs worldwide. School-aged children are most often affected. Since the diagnosis is mainly clinical, physicians should be well-versed in the clinical manifestations of erythema infectiosum to avoid misdiagnosis, unnecessary investigations, and mismanagement of the disease.
OBJECTIVE: The purpose of this article is to familiarize physicians with the wide spectrum of clinical manifestations and complications of erythema infectiosum associated with parvovirus B19 infection.
METHODS: A search was conducted in July 2022 in PubMed Clinical Queries using the key terms \"Erythema infectiosum\" OR \"Fifth disease\" OR \"Slapped cheek disease\" OR \"Parvovirus B19\". The search strategy included all clinical trials, observational studies, and reviews published within the past 10 years. Only papers published in the English literature were included in this review. The information retrieved from the above search was used in the compilation of the present article.
RESULTS: Erythema infectiosum is a common exanthematous illness of childhood caused by parvovirus B19. Parvovirus B19 spreads mainly by respiratory tract secretions and, to a lesser extent, the saliva of infected individuals. Children between 4 and 10 years of age are most often affected. The incubation period is usually 4 to 14 days. Prodromal symptoms are usually mild and consist of lowgrade fever, headache, malaise, and myalgia. The rash typically evolves in 3 stages. The initial stage is an erythematous rash on the cheeks, with a characteristic \"slapped cheek\" appearance. In the second stage, the rash spreads concurrently or quickly to the trunk, extremities, and buttocks as diffuse macular erythema. The rash tends to be more intense on extensor surfaces. The palms and soles are typically spared. Central clearing of the rash results in a characteristic lacy or reticulated appearance. The rash usually resolves spontaneously within three weeks without sequelae. The third stage is characterized by evanescence and recrudescence. In adults, the rash is less pronounced than that in children and is often atypical. Only approximately 20% of affected adults have an erythematous rash on the face. In adults, the rash is more frequently found on the legs, followed by the trunk, and arms. A reticulated or lacy erythema is noted in 80% of cases which helps to distinguish erythema infectiosum from other exanthems. Pruritus is noted in approximately 50% of cases. The diagnosis is mainly clinical. The many manifestations of parvovirus B19 infection can pose a diagnostic challenge even to the best diagnostician. Complications include arthritis, arthralgia, and transient aplastic crisis. In most cases, treatment is symptomatic and supportive. When parvovirus B19 infection occurs in pregnant women, hydrops fetalis becomes a real concern.
CONCLUSIONS: Erythema infectiosum, the most common clinical manifestation of parvovirus B19 infection, is characterized by a \"slapped cheek\" appearance on the face and lacy exanthem on the trunk and extremities. Parvovirus B19 infection is associated with a wide spectrum of clinical manifestations. Physicians should be aware of potential complications and conditions associated with parvovirus B19 infection, especially in individuals who are immunocompromised, chronically anemic, or pregnant.

Parvovirus B19 (B19V) is pathogenic to humans and causes various human diseases. However, no antiviral agents or vaccines currently exist for the treatment or prevention of B19V infection. Therefore, developing sensitive and specific methods for B19V infection diagnosis is essential for accurate diagnoses. Previously, a Clustered Regularly Interspaced Palindromic Repeats (CRISPR)-Cas12a (cpf1)-based electrochemical biosensor (E-CRISPR) with a picomole sensitivity for B19V detection was established. Herein, we set up a novel nucleic acid detection system based on Pyrococcus furiosus Argonaute (PfAgo)-mediated nucleic acid detection, targeting the nonstructural protein 1 (NS1) region of the B19V viral genome (abbreviated B19-NS1 PAND). Benefiting from independent protospacer adjacent motif (PAM) sequences, PfAgo can recognize their target with guide DNA (gDNA) that is easy to design and synthesize at a low cost. In contrast to E-CRISPR, without preamplification with Polymerase Chain Reaction (PCR), the Minimum Detectable Concentration (MDC) of three guide- or single guide-mediated B19-NS1 PAND was about 4 nM, approximately 6-fold more than E-CRISPR. However, when introducing an amplification step, the MDC can be dramatically decreased to the aM level (54 aM). In addition, the diagnostic results from clinical samples with B19-NS1 PAND revealed 100% consistency with PCR assays and subsequent Sanger sequencing tests, which may assist in molecular testing for clinical diagnosis and epidemiological investigations of B19V.

Immunosuppressed patients can contract parvovirus B19, and some may experience hemophagocytic lymphohistiocytosis (HLH). Herein, we describe the first report of hemophagocytic lymphohistiocytosis in a heart-lung transplant patient with concomitant parvovirus B19 infection. The patient was treated with intravenous immune globulin (IVIG) and the features of HLH were remission. This instance emphasizes the significance of parvovirus B19 monitoring in transplant patients with anemia; if HLH complicates the situation, IVIG may be an adequate remedy. Finally, a summary of the development in diagnosing and managing parvovirus B19 infection complicated by HLH is provided.

Human parvovirus B19 (HPV B19) is pathogenic to human, which can cause fifth disease, transient aplastic crisis, arthritis, myocarditis, autoimmune disorders, hydrops fetalis, and so on. Currently, no approved vaccines or antiviral drugs are available against HPV B19, and thus the development of effective vaccines is needed. The capsid of HPV B19 is composed of two types of proteins, i.e., the major capsid protein VP2 and the minor protein VP1. Previous experimental studies have shown that the dominant immune responses against HPV B19 are elicited by VP1, especially the unique region on the N-terminus of VP1. It has been found that VP2 alone or VP2 and VP1 together can assemble into virus-like particle (VLP). The VLP structure formed by VP2 has been resolved, however, the location of VP1 in the capsid, especially the location of VP1 unique region with strong immunogenicity, is still not clear. In the present work, using the Hansenula polymorpha expression system developed by our laboratory, two kinds of recombinant HPV B19 VLPs were expressed, i.e., the VLP co-assembled by VP1 and VP2 (VP1/VP2 VLP) and the VLP whose VP1 content was improved (VP1h/VP2 VLP). The expression, purity, and morphology of these two VLPs were characterized, and then their immunogenic properties were investigated and compared with those of the VLP containing VP2 alone (VP2 VLP) previously developed by our group. Furthermore, the location of the VP1 unique region in the VLPs was determined by using the immunogold electron microscopy (IGEM). Our experimental results show that the VP1h/VP2 VLP elicits a stronger neutralization against the HPV B19 than VP2 and VP1/VP2 VLPs, which implies that the increase of VP1 content significantly improves the level of neutralizing antibodies. In addition, the IGEM observations suggest that the unique region of VP1 may be located inside the recombinant VLP. The VLPs recombinantly expressed by our Hansenula polymorpha system may serve as a promising candidate immunogen for HPV B19 vaccine development.

Background: Parvovirus B19 (B19V) infection is a rare cause of severe anemia in liver transplant recipients. However, few studies have systematically reviewed reported cases and summarized experience in managing this disease. Objective: We described a retrospective case series of eight adult liver transplant recipients with B19V-associated severe anemia and performed a literature review of epidemiology, etiology, clinical courses, diagnosis, treatment options available, and outcomes of B19V-associated anemia in adult liver transplant recipients. Patients and Methods: We systematically reviewed articles describing adult liver transplant recipients with B19V-associated anemia from PubMed and ScienceDirect databases from database inception to May 2022. Results: Eight articles containing 23 cases were identified in addition to eight cases from our center for a total of 31 patients (mean age, 45.7 ± 9.7 years; 74.2% male). Eighty-seven percent developed transfusion-dependent anemia within two months after liver transplantation (LT). Fever and progressive anemia are among the major manifestations. Intravenous immunoglobulin (IVIG)-based therapy was given to all patients and the treatment protocols varied among different centers. Except for two cases who died of comorbidities, 17 patients obtained long-term recovery from anemia after one course of treatment and six (19%) experienced relapses that were reversed by repeated courses of IVIG therapy. Two recipients presented with IVIG-associated side effects and two developed acute cellular rejection (ACR) after reduction of immunosuppression. Conclusions: B19V infection should be suspected early as a cause of severe anemia of unknown etiology in adult liver transplant recipients. The clearance of B19V typically lags behind recovery of anemia, and inadequate clearance of virus after cessation of IVIG appears to be a potential risk of anemia recurrence. Moreover, more attention should be paid to the side effects of high-dose IVIG infusion and ACR because of reduction of immunosuppression.

There is a lack of epidemiological studies on the course and clinical characteristics of Parvovirus B19 (B19V) infections in kidney transplant (KT) recipients. This study was undertaken to provide recommendations for clinical B19V infection diagnosis and treatment.
Serum samples of KT recipients were regularly collected and tested for B19V-DNA copies, B19V-IgG/IgM levels, as well as hematological parameters and functions of kidney and liver. The course of B19V infection was described according to the results of serology and DNA testing, and the clinical and epidemiological data were combined for analysis.
75% B19V infections occurred within 2 weeks after KT(n = 9). The infection rate of B19V in KT recipients was high, namely 10.17% (n = 12). The number of 10 patients IgM antibodies against B19V (IgM+) and theDNA B19V (DNA+), whereas 2 patients were IgM negative (IgM-) but DNA+. The B19V infected KT patients showed several symptoms, including anemia (100%), reduction of platelets (8.33%), and damage to liver (75%) and kidney function (16.67%) Patients with progressive anemia in the first two weeks after KT, which combined with the decrease of reticulocytes, are more likely to have B19V infection. Associations of four main therapeutic risk factors for B19V infections in KT patients have been analyzed. B19V infection was associated with use of basiliximab (OR = 1.19; 95%- CI: 1.08-1.32; P = 0.003) and use of thymoglobulins (OR = 0.84; 95%-CI: 0.76-0.93; P = 0.003).
Doctors should be alert to B19V infection, especially in the immunodeficient patients within the first two weeks after transplantation.

Parvovirus B19 (B19V) as a human pathogenic virus, would cause a wide range of clinical manifestations. Besides the supportive and symptomatic treatments, the only FDA-approved antiviral drug for the treatment of B19V is intravenous immunoglobulins, which however, have limited efficacy and high cost. By far, there are still no virus-specific therapeutics clinically available to treat B19V infection. Therefore, exploiting the potential targets with a deep understanding of the life cycle of B19V, are pivotal to the development of B19V-tailored effective antiviral approaches. This review will introduce antiviral agents via blocking viral invasion, inhibiting the enzymes or regulatory proteins involved in DNA synthesis, and so on. Moreover, nanotechnology-enabled approaches against B19V will also be outlined and discussed through a multidisciplinary perspective involving virology, nanotechnology, medicine, pharmaceutics, chemistry, materials science, and other fields. Lastly, the prospects of the antiviral agents and nanosystems in terms of fabrication, clinical translation and potential breakthroughs will be briefly discussed.

UNASSIGNED: Parvovirus B19 (B19V) infection is a viral threat after kidney transplantation. It is mainly transmitted by close-contact inhalation of aerosolized viral particles. The risk of nosocomial spread of B19V in the transplantation ward is quite high. This study aimed to evaluate the quality of routine disinfection and the effectiveness of isolation measures in the wards of B19V-infected kidney transplant recipients.
UNASSIGNED: Throat swab samples of 19 kidney transplant recipients admitted to the isolation ward and three healthcare workers (HCWs) were collected for viral DNA detection. Routine disinfection procedures were performed twice a day in general and B19V isolation wards. Environmental surface and air samples were collected for viral DNA detection before and after disinfection.
UNASSIGNED: A total of four patients were diagnosed with B19V infection and transferred to the B19V isolation ward, of which only two had positive throat swab samples. The other 15 patients and all HCWs tested negative for B19V. A total of 88 environmental surface and air samples were collected. Eight of the environmental samples collected in the B19V isolation ward before disinfection tested positive for B19V, while one sample tested positive after disinfection. In the general wards, all environmental samples collected before disinfection tested negative for B19V. All 24 samples collected from ambient air, whether in B19V isolation or general wards, before or after disinfection, tested negative for B19V.
UNASSIGNED: Existing methods of routine or terminal disinfection for air and object surfaces were effective in eliminating B19V from object surfaces and ambient air in the isolation and general wards. Material surfaces that are exposed to high frequency and easily contaminated by blood, body fluids, and indoor air were the focus of cleaning and disinfection. Nosocomial cross-infection of other immunocompromised patients and HCWs can be avoided if appropriate prevention and control measures are taken.

Parvovirus B19 (PvB19) infection and PvB19 related pure red cell aplasia (PRCA) in recipients with allogeneic hematopoietic stem cell transplantation have been reported sporadically. However, clinical studies with large sample sizes are lacking, especially in patients undergoing HLA-haploidentical peripheral blood stem cell transplantation (haplo-PBSCT). In addition, clinical features, immune reconstitution, and outcomes of these patients are not clear. We conducted a retrospective analysis of 164 patients who received haplo-PBSCT with low-dose anti-thymocyte globulin (ATG) plus low-dose posttransplant cyclophosphamide (PTCy)-based regimen as graft-versus-host disease (GVHD) prophylaxis. We analyzed the incidence of PvB19 related PRCA and compared the clinical characteristics, immune reconstitution, incidence of GVHD, relapse rate, and survival between patients with and without PvB19 related PRCA. A total of 14 (8.5%) recipients developed PvB19 related PRCA after a median of 5.3 months after haplo-PBSCT. These patients with PvB19 related PRCA had slower immune reconstitution, but similar incidences of GVHD, relapse rate, and overall survival compared with recipients without PvB19 related PRCA. PvB19 related PRCA indicated relative delayed and poor immune reconstitution of the recipients early after haplo-PBSCT. PvB19 related PRCA had no effects on GVHD, relapse, and survival.