Marialinda Vatteroni

Human Metapneumovirus Associated with Respiratory Tract Infections in a 3-Year Study of Nasal Swabs from Infants in Italy

ABSTRACT The newly described human metapneumovirus (hMPV) is reported here to be more commonly associated with lower respiratory tract disease. The present study examined nasal swab specimens from 90 infants with acute respiratory tract infections in Pisa, Italy, over a period of three respiratory virus seasons. The incidence of infection varied in each of the 3 years, with the rates of positivity for hMPV being 7% in 2001 but 37 and 43% in 2000 and 2002, respectively. hMPV was noted to occur seasonally in a pattern typical of the frequency of occurrence of respiratory syncytial virus. More than one-half (14 of 23) of the infants infected with hMPV had bronchopneumonia. One-third (9 of 23) of the hMPV-infected patients were also infected with another respiratory virus, a relationship that has not previously been reported. Mixed infections did not account for a higher percentage of cases of bronchopneumonia than hMPV infection alone did. Furthermore, 7 of 17 infants whose plasma was also tested for hMPV RNA were demonstrated to have virus in both nasal swab and blood specimens. The study indicates that hMPV is seen as commonly as other respiratory viruses, may be associated with severe respiratory disease in infants, can establish mixed infections with other respiratory viruses, and has a seasonal occurrence.

TT virus in the nasal secretions of children with acute respiratory diseases: relations to viremia and disease severity.

ABSTRACT The natural history and pathogenic potential of the recently identified TT virus (TTV) are currently a matter of intensive investigation. In an attempt to shed some light on these issues, nasal and blood specimens of 1- to 24-month-old children hospitalized with a clinical diagnosis of acute respiratory disease (ARD) were examined for the presence, load, and genetic characteristics of TTV. The results have indicated that at least in young children, the respiratory tract not only represents a route by which abundant TTV can be shed into the environment but also may be a site of primary infection and continual replication. Although we found no compelling evidence that TTV was the direct cause of ARD in some of the children studied, the average loads of TTV were considerably higher in patients with bronchopneumonia (BP) than in those with milder ARD, raising interesting questions about the pathophysiological significance of TTV at this site. Furthermore, group 4 TTV was detected almost exclusively in children with BP.

TT virus loads and lymphocyte subpopulations in children with acute respiratory diseases

ABSTRACT TT virus (TTV) produces chronic plasma viremia in around 90% of healthy individuals of all ages and has, therefore, been proposed as a commensal human virus. We recently demonstrated that in children hospitalized for acute respiratory diseases high TTV loads were associated with severe forms of disease. Here, we report that in such children TTV loads showed an inverse correlation with the percentage of circulating total T and helper T cells and a direct correlation with the percentage of B cells. Thus, florid TTV replication might contribute to lymphocyte imbalances and, possibly, immunosuppressive effects, thus resembling related animal viruses.

Dynamics of Persistent TT Virus Infection, as Determined in Patients Treated with Alpha Interferon for Concomitant Hepatitis C Virus Infection

ABSTRACT TT virus (TTV) is a recently identified widespread DNA virus of humans that produces persistent viremia in the absence of overt clinical manifestations. In an attempt to shed light on the dynamics of chronic infection, we measured the levels of TTV in the plasma of 25 persistently infected patients during the first 3 months of alpha interferon (IFN-α) treatment for concomitant hepatitis C virus (HCV) infection. The first significant decline of TTV loads was observed at day 3 versus day 1 for HCV. Subsequently, the loads of TTV became progressively lower in most patients, but some initial responders relapsed before the end of the follow-up, suggesting that at least in some subjects the effects of IFN on TTV can be very short-lived. No correlation between the responses of TTV and HCV to therapy was found. Fitting the viremia data obtained during the first week of treatment into previously developed mathematical models showed that TTV sustains very active chronic infections, with over 90% of the virions in plasma cleared and replenished daily and a minimum of approximately 3.8 × 1010 virions generated per day. Low levels of TTV were occasionally detected in the peripheral blood mononuclear cells of patients who had cleared plasma viremia, thus corroborating previous results showing that these cells may support TTV replication and/or persistence.

Relationships between total plasma load of torquetenovirus (TTV) and TTV genogroups carried.

ABSTRACT In 239 torquetenovirus-positive people, multiple-genogroup infections were common and associated with higher viral loads than would be expected from simple additive effects. The latter observation was restricted to the infections which included both genogroups 1 and 3, pointing to the possible existence of some kind of infection facilitation between these genogroups.

Comparative evaluation of five rapid methods for identifying subtype 1b and 2c hepatitis C virus isolates.

A panel of 61 HCV isolates belonging to five different subtypes were used to evaluate five methods for rapid typing of HCV RNA: an in-house type-specific polymerase chain reaction based on the core region (type-specific PCR), a commercial amplification of the core region followed by hybridisation to probe coated wells (DEIA), a commercial amplification of the 5-UTR region followed by hybridisation to probes immobilised on strips (LiPA), an in-house restriction fragment polymorphism analysis of the 5UTR (RFLP), and a commercial serological method using synthetic peptides from the NS4 region (serotyping). The correct viral type was identified in 90% of cases by DEIA, in 82% of cases by type-specific PCR, in 80% of cases by LiPA and RFLP, and in 67% of cases by serotyping. Correct identification of the virus subtype was much less frequent and was beyond the performance characteristics of some assays. Major problems were found in the identification of isolates belonging to type 2. This was probably at least partly due to the fact that all type 2 isolates in the viral panel were of subtype 2c, which has been considered rare until recently.

Hepatitis C virus serological and polymerase chain reactions in human immunodeficiency virus-positive and -negative patients.

BACKGROUNDnPolytransfused patients may be dually infected with hepatitis C virus (HCV) and human immunodeficiency virus (HIV).nnnOBJECTIVESnTo assess the correlation of antibodies to HCV with viral RNA in serum as determined by polymerase chain reaction (PCR) in anti HIV-positive and -negative haemophiliacs.nnnSTUDY DESIGNnSerum from 150 Patients with or without HIV infection were examined for anti-HCV by second generation enzyme-linked immunosorbent assay (ELISA) and recombinant immunoblotting assay (RIBA). A sample was also tested in a nested-reverse transcription PCR for a conserved sequence of the 5 untranslated region of HCV. PCR-positive specimens were titrated and a type-specific PCR using viral core gene sequences was used to determine distribution of HCV viral types.nnnRESULTSnEighty-seven percent of the patients were positive in ELISA. All the positives but 2 were either positive of indeterminate in RIBA. The frequency of indeterminate RIBA results was 33% among HIV-positive subjects and less than 1% among HIV-negative ones. PCR was positive in 68% of 73 RIBA-positive or -indeterminate individuals and negative in all HCV-seronegative individuals examined. No significant differences were observed in HCV viral type, prevalence or titers of viraemia between HIV-positive or -negative patients.nnnCONCLUSIONSnThe majority (68%) of anti-HCV-positive haemophiliacs examined in this study had HCV RNA in their sera and anti-HCV profile determined by RIBA had no apparent influence on viraemia. The presence of HIV infection in these patients had no significant impact on HCV RNA prevalence, titer or HCV type distribution.