WU polyomavirus in children with acute lower respiratory tract infections, South Korea

Human polyomaviruses, WU and KI in HIV exposed children with acute lower respiratory tract infections in hospitals in South Africa

BACKGROUND

The importance of two recently identified polyomaviruses, WUV and KIV, as respiratory pathogens in populations with a high HIV prevalence needs to be defined, since human polyomaviruses can cause significant morbidity and mortality in patients with immunosuppression. Geographic distribution and disease association of WUV and KIV genotypes are not yet clearly defined.

OBJECTIVES

To investigate the prevalence of WUV and KIV in HIV-positive and HIV-negative patients with respiratory infections in hospitals in South Africa and determine their genotypes.

STUDY DESIGN

Specimens from patients with acute respiratory infections from hospitals serving Pretoria were screened for WUV and KIV. Positive specimens were sequenced and subjected to phylogenetic analysis.

RESULTS

WUV was identified in (7%) and KIV in (1%) of mainly pediatric patients. Co-infections were common in WUV- and KIV-infected patients (71% and 66.6%, respectively); 57% of patients with WUV and 33% of patients with KIV were HIV-positive while the HIV prevalence in the respiratory virus patient group screened in this study was 33% WUV and KIV patients presented with moderate to severe lower respiratory tract disease. Four distinct and 2 unique WUV strains were identified clustering into 2 of 4 globally identified genotypes. KIV strains were identical to strains from Sweden.

CONCLUSION

WUV is frequently detected in HIV-infected patients with respiratory disease, but its role as respiratory pathogen remains uncertain.

Detection of WU polyomavirus DNA by real-time PCR in nasopharyngeal aspirates, serum, and stool samples

Background

The human WU polyomavirus (WUPyV) has been recently described as a novel virus in respiratory tract samples.

Objective

To investigate the viral load of WUPyV in nasopharyngeal aspirates (NPAs), stool, and serum samples of pediatric patients with acute respiratory tract diseases.

Study design

We established a real-time PCR for WUPyV DNA and tested NPA obtained between 2002 and 2007 from pediatric in-patients with acute respiratory tract diseases. In addition, 14 stool and 14 serum samples of children with WUPyV DNA positive NPA were analysed.

Results

WUPyV DNA was found in 5.2% of 1232 NPA. The median viral load in the NPA was 950 copies/ml (maximum 3.4E10 copies/ml). The WUPyV load in NPA was neither associated with the coinfection status nor with the clinical diagnoses. WUPyV DNA was found in 3 of 14 serum samples and in 2 of 14 stool samples. The WUPyV load in NPA tended to be higher in viremic children.

Conclusion

WUPyV DNA was found in NPA, serum, and stool of hospitalised children with acute respiratory tract diseases. Further studies are necessary to determine whether WUPyV is a human pathogen.

Role of human polyomaviruses in respiratory tract disease in young children

KI virus was detected in respiratory secretions of 8/367 (2.2%) symptomatic and 0/96 asymptomatic children (p = 0.215). WU virus was detected in 26/367 (7.1%) symptomatic and 6/96 (6.3%) asymptomatic children (p = 1.00). These human polyomaviruses may not independently cause respiratory tract disease in young children.

Prevalence and pathogenicity of WU and KI polyomaviruses in children, the Netherlands

A longitudinal study in 2004 and 2005 detected polyomaviruses WU and KI in 44% and 17% of children with and without respiratory symptoms, respectively, in the Netherlands. In some children both viruses were detected for long periods. In several symptomatic children no other respiratory pathogen was detected.

The role of polyomaviruses in human disease

The human polyomaviruses, BK virus and JC virus, have long been associated with serious diseases including polyomavirus nephropathy and progressive multifocal leukoencephalopathy. Both viruses establish ubiquitous, persistent infections in healthy individuals. Reactivation can occur when the immune system is impaired, leading to disease progression. Recently, the human polyomavirus family has expanded with the identification of three new viruses (KI, WU and Merkel cell polyomavirus), all of which may prove to be involved in human disease. This review describes the general aspects of human polyomavirus infections and pathogenicity. Current topics of investigation and future directions in the field are also discussed.

A single-tube, real-time PCR assay for detection of the two newly characterized human KI and WU polyomaviruses

BACKGROUND

Three new human polyomaviruses have been recently described, and investigating their in vivo biology and pathogenicity will require sensitive and rational detection assays.

OBJECTIVES

To develop and evaluate a sensitive and rational assay for detection of the newly identified KI and WU polyomaviruses.

STUDY DESIGN

A single-tube, dual-probe, real-time PCR assay for simultaneous detection and discrimination of KI and WU polyomaviruses was developed.

RESULTS

The assay had near single-molecule sensitivity for both viruses and no cross-reactivity was observed. A panel of 637 nasopharyngeal aspirates was screened, resulting in a frequency of 1.4% for KIPyV and 1.3% for WUPyV.

CONCLUSIONS

The dual-probe assay provides a rational approach for further studies of KIPyV and WUPyV.

[Polyomavirus newly discovered]

Three new polyoma viruses have been recently identified; two of them, the KI et WU viruses are present in nasopharyngeal aspirates during the course of acute respiratory infections. The incidence of these viruses is low compared to other respiratory viruses and the disease has not shown a high severity of clinical signs. The physiopathology of the diseases and the mode of cultivation of these viruses remain unknown. The third virus was discovered from cutaneous biopsies of Merkel tumours with a higher incidence than in tissue from healthy patients. Its mode of transmission and its role in the cancerogenesis need more studies. However, as the virus can integrate into the cellular DNA, it signifies that the virus may have a role in various human tumors.

WU and KI polyomavirus present in the respiratory tract of children, but not in immunocompetent adults

BACKGROUND

Recently, two new polyomaviruses (PyV), termed WUPyV and KIPyV, were identified in respiratory tract specimens from children with acute respiratory tract infections (ARTIs). However, their roles in the disease have not been determined.

OBJECTIVES

To determine the prevalence of WUPyV and KIPyV in the Chinese population suffering from ARTIs in Beijing, China, and to examine their possible role in causing disease.

STUDY DESIGN

Nasopharyngeal aspirates, nasal swabs and throat swabs were collected from 415 children and 297 immunocompetent adults with lower ARTIs (LARTIs). The specimens were screened by polymerase chain reaction for the presence of WUPyV, KIPyV, and other common respiratory pathogens.

RESULTS

Although none of the adults sampled were positive for either virus, WUPyV in 10 (2.4%) children and KIPyV was detected in 2 (0.5%) of the children sampled, respectively. Eleven of the positive cases were co-detected with either rhinovirus (6/11), respiratory syncytial virus (4/11), parainfluenzavirus virus (3/11) or Mycoplasma pneumoniae (2/11). Phylogenetic analysis of the WUPyV and KIPyV isolates showed that the nucleotide sequences were homologous to those of previously reported strains.

CONCLUSIONS

The presence of WUPyV and KIPyV in samples from children but not from immunocompetent adults suffering from LARTIs suggests that these viruses primarily infect the young population. Co-detection of additional respiratory pathogens in most of the specimens containing either WUPyV or KIPyV suggests that these viruses do not cause disease independently.

Prevalence of human KI and WU polyomaviruses in children with acute respiratory tract infection in China

The KI and WU polyomaviruses were found in 11 (2.7%) and 17 (4.2%) of 406 nasopharyngeal aspirates, respectively, from children with acute respiratory tract infection (ARTI). The phylogenetic analysis indicates that they are all in the same cluster as the prototype strains. Our findings suggest that they are common in children with ARTI in China.

Detection and discrimination of WU/KI polyomaviruses by real-time PCR with melting curve analysis

WU and KI polyomaviruses are novel viruses of the Polyomaviridae family, which have been identified recently in respiratory secretions from patients with acute respiratory tract infection. Their potential role in respiratory disease is still unclear and requires additional investigation. To facilitate further studies and diagnosis, a real-time PCR with melting curve analysis was optimized and evaluated to detect WU and KI polyomaviruses. Primers specific for the VP1 gene were designed from regions conserved among WU and KI polyomaviruses which provided amplification products of 198 and 231bp corresponding to WU and KI, respectively and thus yielded a difference in melting temperature (Tm) between WU and KI polyomaviruses. The assay proved highly specific for WU and KI polyomaviruses as no cross amplification was detected with other respiratory viruses or human genomic DNA. The assay was also highly sensitive with a detection limit as low as 10copies/microL for both WU and KI polyomaviruses. The performance of the real-time PCR assay was evaluated in terms of amplification efficiency (92%). Finally, the assay was validated using DNA extracted from clinical respiratory specimens for WU and KI polyomaviruses and the results were confirmed by direct nucleotide sequencing. The results obtained by melting curve analysis were in perfect agreement with nucleotide sequencing. In conclusion, this method is advantageous because it is rapid, specific, sensitive, reproducible, accurate, cost-effective and thus, would be feasible and attractive for large-scale analysis aimed at investigating the clinical role of WU and KI polyomaviruses.

Emerging respiratory agents: new viruses for old diseases?

The recent advances in molecular technology have enabled the detection of several new viral agents in specimens collected from the human respiratory tract. Human metapneumovirus was first described in 2001, and is a significant respiratory pathogen, particularly of children. Following the identification of severe acute respiratory syndrome (SARS) associated coronavirus, two other newly detected coronaviruses, NL63 and HKU1, have been linked to respiratory disease in humans. However, identifying a new virus as the causative agent of a specific disease is difficult, and ideally would involve satisfying Koch's postulates. The recently described human bocavirus and polyomaviruses KI and WU have been detected in samples collected from humans with acute respiratory infection, but as yet, have not been conclusively proven to be agents of human disease. We review the new viral agents that have been detected in respiratory samples since 2001, and examine their contribution as agents of human disease.

Age-related pattern of KI and WU polyomavirus infection

Background

The role of two recently identified polyomaviruses, KI and WU, in the causation of respiratory disease has not been established.

Objectives

To determine the prevalence of KI and WU viruses (KIV and WUV) in 371 respiratory samples and evaluate their contribution to respiratory disease.

Study Design

Specimens were screened for KIV and WUV using single, multiplex or real time PCR; co-infection with other respiratory viruses was evaluated.

Results

Of the 371 samples analysed, 10 (2.70%) were positive for KIV and 4 (1.08%) were positive for WUV yielding an overall case prevalence of KIV and WUV infection of 3.77%. KIV and WUV were identified in patients aged <15 years (11 patients) with upper or lower respiratory tract infection and >45 years (3 patients) with upper respiratory tract infection. Co-infections were found in 5 (50%) and 3 (75%) of the KIV and WUV positive samples, respectively.

Conclusions

This study supports previous conclusions that KIV and WUV detection in the respiratory tract may be coincidental and reflect reactivation of latent or persistent infection with these viruses. The age distribution of KIV and WUV infection in this study mirrors that found for the other human polyomaviruses, BK and JC.

Prevalence and molecular characterization of WU/KI polyomaviruses isolated from pediatric patients with respiratory disease in Thailand

WU and KI polyomaviruses represent novel viruses discovered in respiratory secretions from human patients with acute respiratory tract infection. However, the association between WU/KI polyomaviruses and human disease has remained unclear. In this study, the prevalence of these two novel viruses and occurrence of co-infection with other respiratory viruses were determined in Thai pediatric patients with respiratory disease. Previously described PCR assays were applied to detect WU/KI polyomaviruses as well as other respiratory viruses in 302 nasopharyngeal suction specimens collected from February 2006 through February 2007. The results revealed the anneal prevalence of WU and KI polyomaviruses in the Thai population was 6.29% and 1.99%, respectively. The frequency of co-detection of WU and KI polyomaviruses with other respiratory viral pathogens was 42.11% and 33.33%, respectively. Moreover, each of the two complete genome sequences of WU (CU_295 and CU_302) and KI (CU_255 and CU_258) polyomaviruses were genetically and phylogenetically characterized. Sequence analysis showed that they contained features common to those found in previous studies. However, there were several nucleotide variations within the non-coding regulatory regions and various non-synonymous mutations within the coding regions which may influence virulence and pathogenesis of these viruses. Nevertheless, it is still possible that these viruses are not the causative agents of clinical respiratory disease. Therefore, judging the association of WU/KI polyomavirus infections with a particular disease will be challenging and require more comprehensive case control investigations.

WU polyomavirus in children with acute lower respiratory tract infections, China

Background

WU polyomavirus (WUPyV), a new member of the genus of Polyomavirus in the family Polyomaviridae, has been found and associated with respiratory tract infections recently. However, its clinical role and pathogenicity has not been known.

Objectives

To confirm that WU polyomavirus has been found in Chinese children.

Study design

WU polyomavirus was detected and identified using PCR methods. A total of 278 specimens of nasopharyngeal aspirate were collected, and then PCR products were sequenced directly.

Results

One of 278 nasopharyngeal aspirates was positive for WUPyV in one child, and the positive rate was 0.4%. The results showed that the sequences of genome, LTAg and VP2 gene was identical to the reference sequences of WU polyomavirus prototype strains.

Conclusions

We confirmed that WU polyomavirus had been found and identified in the respiratory secretions in China.