Quantitative real-time PCR for differential diagnostics of parvovirus B19 infection in acute liver failure patients

Vasconcelos D, Côrtes MF, Costa SF, Mendoza TRT, Gomes HR, Witkin SS, Mendes-Correa MC. Encephalopathy Caused by Human Parvovirus B19 Genotype 1 Associated with Haemophilus influenzae Meningitis in a Newborn

Parvovirus B19 infection is associated with a wide range of clinical manifestations, from asymptomatic to severe neurological disorders. Its major clinical symptoms, fever and rash, are common to multiple viruses, and laboratory tests to detect B19 are frequently not available. Thus, the impact of B19 on public health remains unclear. We report the case of a 38-day old girl admitted to São Paulo Clinical Hospital, Brazil, with an initial diagnosis of bacterial meningitis, seizures, and acute hydrocephalus. Antibiotic therapy was maintained for one week after admission and discontinued after negative laboratory results were obtained. Nine days after symptoms onset, a cerebral spinal fluid (CSF) sample revealed persistent pleocytosis. The complete B19 complete genome was subsequently identified in her CSF by a metagenomic next-generation sequencing approach. This report highlights the possible involvement of B19 in the occurrence of acute neurological manifestations and emphasizes that its possible involvement might be better revealed by the use of metagenomic technology to detect viral agents in clinical situations of unknown or uncertain etiology.

Clinical Presentation of Parvovirus B19 Infection in Adults Living with HIV/AIDS: A Case Series

Parvovirus B19 (B19V) infection varies clinically depending on the host's immune status. Due to red blood cell precursors tropism, B19V can cause chronic anemia and transient aplastic crisis in patients with immunosuppression or chronic hemolysis. We report three rare cases of Brazilian adults living with human immunodeficiency virus (HIV) with B19V infection. All cases presented severe anemia and required red blood cell transfusions. The first patient had low CD4⁺ counts and was treated with intravenous immunoglobulin (IVIG). As he remained poorly adherent to antiretroviral therapy (ART), B19V detection persisted. The second patient had sudden pancytopenia despite being on ART with an undetectable HIV viral load. He had historically low CD4⁺ counts, fully responded to IVIG, and had undiagnosed hereditary spherocytosis. The third individual was recently diagnosed with HIV and tuberculosis (TB). One month after ART initiation, he was hospitalized with anemia aggravation and cholestatic hepatitis. An analysis of his serum revealed B19V DNA and anti-B19V IgG, corroborating bone marrow findings and a persistent B19V infection. The symptoms resolved and B19V became undetectable. In all cases, real time PCR was essential for diagnosing B19V. Our findings showed that adherence to ART was crucial to B19V clearance in HIV-patients and highlighted the importance of the early recognition of B19V disease in unexplained cytopenias.

Use of oral fluid samples for the investigation of outbreaks of human parvovirus B19 infection

The use of oral fluid (OF) samples for serological diagnosis of parvovirus B19 infection during outbreaks of erythema infectiosum had already been demonstrated, but the feasibility of using OF for the characterization of B19 genotypes circulating during outbreaks has not been described. The aim of this study was to assess the use of "in-house" PCR-based assays as a powerful tool for a rapid diagnosis and molecular characterization of B19 strains in OF samples during outbreaks. Paired serum and OF samples collected from anti-B19 IgM-positive patients, during two outbreaks of ertythema infectiosum (1999-2000 and 2004-2005), were tested by conventional (cPCR) and quantitative PCR (qPCR). qPCR was more sensitive than cPCR for detecting B19-DNA in both OF and serum. Overall, OF presented lower viral load (9.97 × 106 UI/mL) than serum (2.42 × 1010 UI/mL) and this difference was statistically significant. All OF samples obtained from patients in the age group < 14 years presented low viral load (< 104 IU/mL). No correlation was found between viral load and the number of days of onset of rash. Sequence analysis from PCR positive OF samples confirmed the circulation of subgenotype 1a (G1a) during these outbreaks. Our findings indicate that PCR-based assays may fail to detect B19-DNA in approximately 50% of OF compared to serum samples. Nevertheless, our study has shown for the first time that the genome sequence of the amplicon from non-invasive clinical sample is useful for molecular genotyping and may be a tool to clarify the genetic diversity of B19 strains circulating in distinct outbreaks.

Evaluation of Molecular Test for the Discrimination of "Naked" DNA from Infectious Parvovirus B19 Particles in Serum and Bone Marrow Samples

Low levels of parvovirus B19 (B19V) DNA can be detected in the circulation and in different tissue of immunocompetent individuals for months or years, which has been linked to inflammatory diseases such as cardiomyopathy, rheumatoid arthritis, hepatitis, and vasculitis. However, the detection of B19V DNA does not necessarily imply that infectious virions are present. This study aimed to evaluate the method based on the Benzonase^® treatment for differentiation between the infectious virions from “naked” DNA in serum and bone marrow (BM) samples to be useful for the B19V routine diagnosis. In addition, we estimated the period of viremia and DNAemia in the sera and bone marrow of nonhuman primates experimentally infected with B19V. Serum samples from ten patients and from four cynomolgus monkeys experimentally infected with B19V followed up for 60 days were used. Most of the human serum samples became negative after pretreatment; however, only decreased viral DNA loads were observed in four patients, indicating that these samples still contained the infectious virus. Reduced B19V DNA levels were observed in animals since 7th dpi. At approximately 45th dpi, B19V DNA levels were below 10⁵ IU/mL after Benzonase^® pretreatment, which was not a consequence of active B19V replication. The test based on Benzonase^® pretreatment enabled the discrimination of “naked DNA” from B19V DNA encapsidated in virions. Therefore, this test can be used to clarify the role of B19V as an etiological agent associated with atypical clinical manifestations.

Persistence of Parvovirus B19 in liver from transplanted patients with acute liver failure

Aim: In this study, we investigated the presence of B19V in liver tissues from patients with acute liver failure (ALF) and evaluated the viral activity in infected liver. Methods: Serum and liver samples from 30 patients who underwent liver transplantation for ALF were investigated for B19V infection by real-time PCR, serological tests and examination of B19V mRNA (transcript) expression in the liver. Results: The serum and liver samples from seven patients were B19V DNA positive (10³-10⁵ copies/ml). Most of them presented detectable anti-B19V IgG, indicating persistent infection. B19V mRNA was detected in all patients, demonstrating intra-hepatic replication. Conclusion: B19V infection of the liver during the course of non-A-E ALF suggested a role of B19V, which produced the worst outcome in co-infected patients and in patients with cryptogenic ALF, in liver damage.

Human parvovirus B19: a review of clinical and epidemiological aspects in Brazil

Since the first evidence of human parvovirus B19 (B19V) infection in late 80s, several studies have been conducted to clarify the spectrum of clinical diseases in Brazil. B19V infection is prevalent in the general population and has exhibited a cyclical pattern of occurrence every 4-5 years, with the predominance of genotype 1 over 3b. During epidemic periods the wide range of clinical conditions, such as ertythema infectiosum, arthropathy, transient aplastic crisis, nonimmune hydrops fetalis and B19V-hepatitis were diagnosed. However, many infections are likely asymptomatic or have a self-limiting clinical course and are not readly diagnosed. Besides, the similarity of the symptoms of ertythema infectiosum to other rash diseases and the broadly circulation of arboviruses makes differential diagnosis more difficult. In this article, we provide a historical comprehensive overview of the research on parvovirus B19 conducted in Brazil, with a focus on the clinical and epidemiological aspects of the infection.

High prevalence of parvovirus B19 infection in patients with chronic kidney disease under hemodialysis: A multicenter study

OBJECTIVES

Parvovirus B19 (B19V) infection is commonly acute and self-limited, but in chronic kidney disease (CKD) patients under dialysis treatment, this infection could increase susceptibility to acute and chronic anemia. The aim of this study was to evaluate the frequency and risk of B19V infection among Brazilian CKD patients under dialysis.

METHODS

A study was conducted among 221 CKD patients and a control group of 142 blood donors. B19V infection was evaluated in serum samples by real-time PCR, and ELISA (anti-B19V IgM and IgG).

RESULTS

B19V DNA was detected in 65% (145/221) of CKD patients, which was significantly higher (p < 0.001) than in the blood donors (6.3%). Simultaneous detection of B19V IgG and viremia was shown in 40.3% of CKD patients, which was indicative of persistent B19V infection. CKD patients showed an increased risk of developing B19V infection (OR = 28.1, CI = 13.5-58.5, p = 0.001).

CONCLUSIONS

Despite an absence of clinical signs of B19V infection, these data highlight the importance of B19V infection in this high-risk population, since a persistent B19V infection could become clinically significant after renal transplant. Moreover, the persistent viremia should be considered as a potential risk, mainly because of the contamination of dialysis equipment.