A prospective 2-year analysis including 322 infant patients with acute respiratory disease (ARD) hospitalized in a pediatric department in northern Italy was carried out to evaluate the role as respiratory pathogens or co-pathogens of recently identified viruses. The presence of respiratory syncitial virus (RSV), human Metapneumoviruses (hMPVs), human Bocaviruses (hBoVs), and human Coronaviruses (hCoVs) was assayed by molecular detection and clinical symptoms evaluated. Nasopharyngeal aspirates from 150 of the 322 infants (46.6%) tested positive for at least one pathogen. Ninety samples (28.0%) tested positive for RSV RNA (61.5% genotype A and 38.5% genotype B), 46 (14.3%) for hMPV RNA (71.7% subtype A and 28.3% subtype B), 28 (8.7%) for hCoV RNA (39.3% hCoV-OC43, 35.7% hCoV-NL63, 21.4% hCoV-HKU1, and 3.6% hCoV-229E), and 7 (2.2%) for hBoV DNA (of the 6 typed, 50% subtype 1 and 50% subtype 2); 21/150 samples revealed the presence of 2 or more viruses. Co-infection rates were higher for hMPVs, hCoVs, and hBoV (38.3%, 46.4%, and 57.1%,) and lower for RSV (23.3%). RSV was associated with the presence of complications (P < 0.001) and hypoxia (P < 0.015). When the presence of RSV alone and the RSV-hMPV co-infections were considered, RSV mono-infected patients resulted to have longer hospitalization and higher hypoxia (P < 0.001). The data highlight that (i) RSV has a central role as a respiratory pathogen of infants, (ii) the wide circulation of recently identified viruses does not reduce the clinical and epidemiological importance of RSV, and that (iii) recently identified agents (hMPVs, hBoVs, and hCoVs) act as primary pathogens or co-pathogens.

Sequential nasopharyngeal aspirates from patients without respiratory symptoms undergoing hematopoietic stem cell transplantation (HSCT) were tested for genomic RNA of human metapneumovirus (hMPV). Persistent hMPV infection was documented in most of them and confirmed by virus isolation. hMPV infection etiology was also evaluated during the same period in samples from pediatric patients with acute respiratory diseases (ARDs). Sequence analysis of hMPV in HSCT recipients documented infection by hMPV genotype A and strong interhost similarity; this pattern differs from that observed in pediatric patients with ARDs. The data indicate that HSCT recipients may frequently develop symptomless hMPV infection.

No abstract

The new H1N1 swine-origin influenza virus (S-OIV) strain is a global health problem. The elucidation of the virus-host relationship is crucial for the control of the new infection. Two human monoclonal antibody Fab fragments (HMab) neutralizing the novel H1N1 influenza strain at very low concentrations were cloned before the emergence of S-OIV from a patient who had a broad-range H1N1 serum neutralizing activity. The two HMabs neutralized all tested H1N1 strains, including S-OIV and a swine strain with IC(50) ranging from 2 to 7 microg/ml. Data demonstrate that infection with previously circulating H1N1 strains can elicit antibodies neutralizing S-OIV. Finally, the human genes coding for the neutralizing HMabs could be used for generating full human monoclonal IgGs that can be safely administered being potentially useful in the prophylaxis and the treatment of this human infection.

Two patterns of viral evolution were observed in the resistant viral populations, driving the variants towards a fast (most of them with G140S + Q148H mutations) or progressive increase in resistance to raltegravir. These results may have implications either for the evaluation of genotypic results, or for the correct clinical use of the compound.