Investigation of a Case of Genotype 5a Hepatitis C Virus Transmission in a French Hemodialysis Unit Using Epidemiologic Data and Deep Sequencing.

BACKGROUND Hepatitis C virus (HCV) is a major cause of chronic liver disease worldwide. A patient was recently found to be HCV seropositive during hemodialysis follow-up. OBJECTIVE To determine whether nosocomial transmission had occurred and which viral populations were transmitted. DESIGN HCV transmission case. SETTING A dialysis unit in a French hospital. METHODS Molecular and epidemiologic investigations were conducted to determine whether 2 cases were related. Risk analysis and auditing procedures were performed to determine the transmission pathway(s). RESULTS Sequence analyses of the NS5b region revealed a 5a genotype in the newly infected patient. Epidemiologic investigations suggested that a highly viremic genotype 5a HCV-infected patient who underwent dialysis in the same unit was the source of the infection. Phylogenetic analysis of NS5b and hypervariable region-1 sequences revealed a genetically related virus (>99.9% nucleotide identity). Deep sequencing of hypervariable region-1 indicated that HCV quasispecies were found in the source whereas a single hypervariable region-1 HCV variant was found in the newly infected patient, and that this was identical to the major variant identified in the source patient. Risk analysis and auditing procedures were performed to determine the transmission pathway(s). Nosocomial patient-to-patient transmission via healthcare workers' hands was the most likely explanation. In our dialysis unit, this unique incident led to the adjustment of infection control policy. CONCLUSIONS The data support transmission of a unique variant from a source with a high viral load and genetic diversity. This investigation also underlines the need to periodically evaluate prevention and control practices.

Serum antibody response to respiratory syncytial virus F and N proteins in two populations at high risk of infection: children and elderly.

Human respiratory syncytial virus (hRSV) is the main viral cause of severe respiratory infections in children and a common cause of morbidity in the elderly. The nucleocapsid (N) and fusion (F) proteins of hRSV were expressed in insect cells and used as antigens in two independent enzyme-linked immunosorbent assays (ELISAs) to measure the serum antibody response in two populations at high risk of hRSV infection, children and the elderly. Fifty-seven serum specimens from children aged from 1 to 10 years old and 91 sera from adults over 60 years old were tested. The ELISA results were compared with those obtained by an immunofluorescence assay (IFA) based on hRSV-infected cells, which was considered as the reference technique. Sensitivity and specificity were 94% and 85% for the N-ELISA and 86% and 81% for the F-ELISA, respectively. When the immune responses of the two groups of individuals were compared, it appeared that almost 100% of the elderly had antibodies against the N or F protein whereas only 50% of the sera from children had antibodies against either of the two viral proteins. In conclusion, the F and N ELISAs can be used successfully for detecting a specific antibody response to hRSV.

Age-associated aggravation of clinical disease after primary metapneumovirus infection of BALB/c mice.

Human metapneumovirus (hMPV) is associated with respiratory tract infections among children and adults. Because hMPV induces significant morbidity and mortality in the elderly, a model of hMPV infection in aged BALB/c mice was established. Young (8 weeks old) and aged (18 months old) mice were intranasally inoculated with hMPV. The infected mice showed respiratory dysfunction, as measured by plethysmography, a marked loss in weight (up to 24%), and severe histopathological abnormalities including bronchiolitis obliterans organizing pneumonia. However, clinical severity was far higher in the aged mice, and none of the young infected mice died. Although virus replication in the lung was greater in the older mice, clearance of virus was not delayed compared to young mice. Production of virus-specific antibody as well as neutralizing antibody was lower. Gamma interferon and monocyte chemotactic protein-1 levels in bronchoalveolar lavage fluid were significantly lower in older mice, whereas interleukin-6 and interleukin-4 levels were significantly higher. We observed by flow cytometry a significant increase in the CD4(+) T lymphocytes (P<0.05) of the aged mice and no difference in CD8(+) T-cell recruitment to the respiratory tract between the two groups. The present study investigated the effects of aging on the immunopathogenesis of hMPV infection and suggests that CD4(+) T lymphocytes, the cytokine response, or a defect in humoral response may be associated with the increased disease severity observed in the aged mice.

Rapid and sensitive detection of metapneumovirus in clinical specimens by indirect fluorescence assay using a monoclonal antibody.

Human metapneumovirus, with two known genotypes named A and B, is associated with mild respiratory symptoms to severe LRTI in children, high-risk adults and the elderly. Rapid and reliable methods of hMPV detection in clinical samples are essential to implement appropriate care, to better understand the pathology of hMPV and to determine its epidemiology. Respiratory samples from 1,386 patients collected during 2 consecutive years were screened for hMPV using indirect immunofluorescence (IFA) assay with a monoclonal antibody. Forty-three patients tested positive for hMPV by the IFA method. In parallel, the samples were examined with RT-PCR on the F gene. Of these, 41 specimens were RT-PCR positive. The remaining two IF positives were cultured and the cultures were subsequently RT-PCR positive. IFA showed therefore a sensitivity of 100%. No false positive signals were obtained with the influenza virus, respiratory syncytial virus or parainfluenza. When tested by RT-PCR, all IFA-negative samples (n = 204)were found negative. Therefore the specificity of IFA was 100%, IC95 [98-100%], with a negative predictive value of 100%. Based upon phylogenetic analysis of the fusion gene, both subgroups of hMPV were efficiently detected by IFA, and the viral aetiology could be given in 2 hr. These results demonstrate the potential usefulness of immunofluorescence with our monoclonal antibody for the rapid detection of hMPV in clinical specimens in the management of therapy and the control of nosocomial diffusion.