MAB8661 Sigma-AldrichAnti-Influenza B Antibody, nucleoprotein, clones B2, B4 Blend

Antigen-specific antibodies are well characterized after vaccination with pandemic H1N1 or seasonal influenza vaccines. However, knowledge on cellular immunity toward pandemic H1N1 after vaccination and infection and cross-reactivities toward seasonal antigens is limited. Nineteen individuals were vaccinated with the pandemic H1N1 vaccine. Among those, ten had been prevaccinated against seasonal influenza. CD4(+) T cells specific for pandemic H1N1 and for seasonal vaccine, and antibodies were monitored using flow cytometry and ELISA/neutralization assays, respectively. In addition, seven patients with acute pandemic influenza infection were analyzed. Pandemic H1N1 vaccination induced a strong 4.63-fold (IQR 4.16) increase in antigen-specific CD4(+) T cells that was more pronounced in individuals not prevaccinated with seasonal influenza (p = 0.01). T-cell levels toward seasonal vaccine concomitantly rose by 2.71-fold (IQR 2.26). Likewise, prevaccination with seasonal influenza induced a less pronounced increase in specific antibodies. Influenza-specific T cells in vaccinees had a Th1 phenotype mainly coexpressing IFN-γ and IL-2, whereas patients with active pandemic influenza showed a shift toward cells predominantly expressing IFN-γ. In conclusion, T cells toward seasonal influenza antigens cross-react with pandemic H1N1 antigens and affect induction of specific T cells after pandemic influenza vaccination. In addition, the cytokine patterns of specific T cells during acute H1N1 infection and after vaccination differ, and the predominantly dual-positive cytokine profile of vaccine-induced T cells suggests sufficient functionality to confer successful virus control.

Human metapneumovirus (hMPV) is a significant cause of acute lower respiratory tract infection in all age groups, particularly in children. Two genetic groups and four subgroups of hMPV have been described. They co-circulate during an epidemic in variable proportions. The aims were to characterize the genotypes of hMPV recovered from children hospitalized for acute lower respiratory tract infection and to establish the molecular epidemiology of strains circulating in Santiago of Chile during a 2-year period. The detection of the N gene by reverse-transcription polymerase chain reaction was carried out for screening 545 infants hospitalized for acute lower respiratory tract infection in Santiago during 2003-2004. The genetic typing of hMPV was performed by analyzing the fusion gene sequences. hMPV was detected in 10.2% (56/545 cases). Phylogenetic analysis of F gene sequences from 39 Chilean hMPV strains identified the two groups and four subgroups previously described. Strains clustered into group A were split further into the sub lineages A1, A2, and A3. Most Chilean strains clustered into the proposed novel A3 sub lineage (59%). A3 viruses were present in both years, while A1 and A2 circulated just in 1 year. In conclusion, hMPV is a relevant cause of acute lower respiratory infection in Chilean children and the potential novel cluster of group A emphasize the need for further regional genetic variability studies.

Human metapneumovirus (hMPV) is a virus, which was first associated with acute lower respiratory infection in children but is detected currently in all age groups. Clinical symptoms are similar to those described for respiratory syncytial virus (RSV) infections, ranging from mild respiratory illness to severe bronchiolitis and pneumonia in children. To date, no cases of hMPV have been reported in Argentina. In this study, 440 respiratory samples obtained during the period 1998-2002 from children under 5 years old with acute respiratory infection were evaluated. Routine detection for RSV, adenovirus, influenza, and parainfluenza was undertaken by immunofluorescent assay. Of the samples negative for these viruses, only 100 were available. All these samples were tested for hMPV by RT-PCR using primers for the L gene. Eleven out of 100 (11%) respiratory samples were positive for hMPV by RT-PCR. A higher frequency of detection was observed in spring. hMPV was detected in all the years studied, except in 2001. Ten out of 11 children positive for hMPV were hospitalized. Median age was 5 months. Of seven patients, five (71%) required oxygen supplementation. The most frequent diagnosis was bronchiolitis (86%), sometimes accompanied by conjunctivitis and otitis media. The present study showed that hMPV was associated with acute lower respiratory infections in children in Buenos Aires, Argentina. This evidence strongly suggests that hMPV is a common pathogen with a wide geographical distribution, which should be included in the routine diagnosis of respiratory viruses in young children.