A two-step real-time PCR assay for quantitation and genotyping of human parvovirus 4

Viral DNA in submandibular gland tissue with an inflammatory disorder

Background

The etiology behind different types of chronic sialadenitis (CS), some of which exhibit IgG4 overexpression, is unknown. Further, IgG4-related disease (IgG4-RD) commonly affects the submandibular gland, but its relationship to IgG4-overexpressing CS, and the antigen triggering IgG4 overexpression, remain unknown.

Materials and Methods

By qPCR, we assessed the presence of 21 DNA-viruses causing IgG4 overexpression in submandibular gland tissue from patients with IgG4-positive and IgG4-negative CS. Healthy submandibular glands and glands with sialolithiasis without CS were used as controls. We examined the distribution of HHV-7, HHV-6B and B19V DNA, within virus PCR-positive tissues with RNAscope in-situ hybridization (RISH).

Results

We detected DNA from seven viruses in 48/61 samples. EBV DNA was more prevalent within the IgG4-positive samples (6/29; 21%) than the IgG4-negative ones (1/19; 5.3%). B19V DNA was more prevalent within the IgG4-negative samples (5/19; 26%) than the IgG4-positive ones (4/29; 14%). The differences in virus prevalence were not statistically significant. Of the IgG4-RD samples (n = 3) one contained HHV-6B DNA. RISH only showed signals of HHV-7.

Conclusions

None of the studied viruses are implicated as triggering IgG4-overexpression in CS. Although our results do not confirm viral etiology in the examined conditions, they provide valuable information on the prevalence of viruses in both diseased and healthy submandibular gland tissue.

Study on genotyping and coinfection rate of human parvovirus 4 among the HTLV-I/II infected blood donors in Khorasan Razavi, Iran

Human Parvovirus 4 (PARV4) is an emerging virus infecting individuals with other blood-borne diseases. This study aimed to determine the prevalence of PARV4 in confirmed HTLVI/II positive samples from blood donors, assessing PARV4 viral load (DNA) and genotyping.

METHODS

A novel qReal-Time PCR, based on a plasmid construct, was developed to simultaneously detect all three PARV4 genotypes using in-house primers and probes. Positive qPCR samples were subjected to nested PCR amplification and subsequent sequencing. Phylogenetic trees were constructed using the Neighbor-joining (N.J.) method.

RESULTS

The coinfection rate of PARV4-DNA in HTLVI/II confirmed infected donors, who were previously deferred, was 14.4 % (13 out of 90), with no observed association with donation status (p = 1.0). Phylogenetic analysis indicated that PARV4-positive samples closely resembled genotype 2 in Iran.qPCR quantification demonstrated significant PARV4 viral loads in positive samples, ranging between 104 and 106 DNA copies/mL of serum.

CONCLUSION

This study presents the first evaluation of HTLVI/II and PARV4coinfection rates among blood donors. Notably, elevated PARV4-DNA titers were detected in HTLVI/II-positive donors. Given PARV's resistance to standard plasma refinery inactivation methods and the absence of its targeted inactivation, its potential impact remains a concern.

Emerging Human Parvoviruses: The Rocky Road to Fame

Parvoviruses are structurally simple viruses with linear single-stranded DNA genomes and nonenveloped icosahedral capsids. They infect a wide range of animals from insects to humans. Parvovirus B19 is a long-known human pathogen, whereas adeno-associated viruses are nonpathogenic. Since 2005, many parvoviruses have been discovered in human-derived samples: bocaviruses 1-4, parvovirus 4, bufavirus, tusavirus, and cutavirus. Some human parvoviruses have already been shown to cause disease during acute infection, some are associated with chronic diseases, and others still remain to be proven clinically relevant-or harmless commensals, a distinction not as apparent as it might seem. One initially human-labeled parvovirus might not even be a human virus, whereas another was originally overlooked due to inadequate diagnostics. The intention of this review is to follow the rocky road of emerging human parvoviruses from discovery of a DNA sequence to current and future clinical status, highlighting the perils along the way.

Simultaneous detection and differentiation of human parvovirus B19 and human parvovirus 4 by an internally controlled multiplex quantitative real-time PCR

Human parvovirus B19 (B19V) and human parvovirus 4 (PARV4) are two parvoviruses known to infect humans and transmit through blood and plasma derived medicinal products (PDMPs). Inactivation of the two parvoviruses has proven to be difficult and nucleic acid testing (NAT) would be an efficient means to exclude viruses. In this study, an internally controlled multiplex quantitative real-time PCR (qPCR) assay for B19V and PARV4 simultaneous detection and quantification was established and evaluated. The optimized multiplex qPCR assay allowed for simultaneous detection of all of the genotypes (1-3) of B19V and PARV4, with equal limit of quantification (LOQ) of 5 copies/μL, rather than other blood-borne viruses. It had a wide dynamic range of reliable amplification linearity of at least 8 orders of magnitude. Low standard deviations (SD) of quantification cycle (Cq) values and low coefficients of variation (CV) of copy numbers for both B19V and PARV4 suggested a high level of repeatability and reproducibility for the multiplex qPCR assay. This multiplex qPCR assay can be served as a readily applicable approach to screen plasma units intended for further manufacturing into PDMPs to reduce the risk of parvoviruses infection by such products and may also be useful for the detection of B19V/PARV4 co-infection or co-existence.

Human parvovirus 4 'PARV4' remains elusive despite a decade of study

Human parvovirus 4 ('PARV4') is a small DNA tetraparvovirus, first reported in 2005. In some populations, PARV4 infection is uncommon, and evidence of exposure is found only in individuals with risk factors for parenteral infection who are infected with other blood-borne viruses. In other settings, seroprevalence studies suggest an endemic, age-associated transmission pattern, independent of any specific risk factors. The clinical impact of PARV4 infection remains uncertain, but reported disease associations include an influenza-like syndrome, encephalitis, acceleration of HIV disease, and foetal hydrops. In this review, we set out to report progress updates from the recent literature, focusing on the investigation of cohorts in different geographical settings, now including insights from Asia, the Middle East, and South America, and discussing whether attributes of viral or host populations underpin the striking differences in epidemiology. We review progress in understanding viral phylogeny and biology, approaches to diagnostics, and insights that might be gained from studies of closely related animal pathogens. Crucial questions about pathogenicity remain unanswered, but we highlight new evidence supporting a possible link between PARV4 and an encephalitis syndrome. The unequivocal evidence that PARV4 is endemic in certain populations should drive ongoing research efforts to understand risk factors and routes of transmission and to gain new insights into the impact of this virus on human health.

Human Parvoviruses

Parvovirus B19 (B19V) and human bocavirus 1 (HBoV1), members of the large Parvoviridae family, are human pathogens responsible for a variety of diseases. For B19V in particular, host features determine disease manifestations. These viruses are prevalent worldwide and are culturable in vitro, and serological and molecular assays are available but require careful interpretation of results. Additional human parvoviruses, including HBoV2 to -4, human parvovirus 4 (PARV4), and human bufavirus (BuV) are also reviewed. The full spectrum of parvovirus disease in humans has yet to be established. Candidate recombinant B19V vaccines have been developed but may not be commercially feasible. We review relevant features of the molecular and cellular biology of these viruses, and the human immune response that they elicit, which have allowed a deep understanding of pathophysiology.

Development of a nanoparticle-assisted PCR (nanoPCR) assay for detection of mink enteritis virus (MEV) and genetic characterization of the NS1 gene in four Chinese MEV strains

Background

Mink enteritis virus (MEV) causes mink viral enteritis, an acute and highly contagious disease whose symptoms include violent diarrhea, and which is characterized by high morbidity and mortality. Nanoparticle-assisted polymerase chain reaction (nanoPCR) is a recently developed technique for the rapid detection of bacterial and viral DNA. Here we describe a novel nanoPCR assay for the clinical detection and epidemiological characterization of MEV.

Results

This assay is based upon primers specific for the conserved region of the MEV NS1 gene, which encodes nonstructural protein 1. Under optimized conditions, the MEV nanoPCR assay had a detection limit of 8.75 × 10¹ copies recombinant plasmids per reaction, compared with 8.75 × 10³ copies for conventional PCR analysis. Moreover, of 246 clinical mink samples collected from five provinces in North-Eastern China, 50.8% were scored MEV positive by our nanoPCR assay, compared with 32.5% for conventional PCR. Furthermore no cross reactivity was observed for the nanoPCR assay with respect to related viruses, including canine distemper virus (CDV) and Aleutian mink disease parvovirus (AMDV). Phylogenetic analysis of four Chinese wild type MEV isolates using the nanoPCR assay indicated that they belonged to a small MEV clade, named “China type”, in the MEV/FPLV cluster, and were closely clustered in the same location.

Conclusions

Our results indicate that the MEV China type clade is currently circulating in domestic minks in China. We anticipate that the nanoPCR assay we have described here will be useful for the detection and epidemiological and pathological characterization of MEV.

Electronic supplementary material

The online version of this article (doi:10.1186/s12917-014-0312-6) contains supplementary material, which is available to authorized users.