Immunohistochemical assessment of respiratory viruses in necropsy samples from lethal non-pandemic seasonal respiratory infections.

BACKGROUND/AIM: Acute respiratory infections are an important cause of childhood morbidity and mortality throughout the world, and viruses have often been reported to be an aetiological agent. This study aimed to identify respiratory viruses in paraffin-embedded samples of paediatric lung necropsy specimens, using immunohistochemistry on tissue microarray slides. METHODS: Retrospective study in 200 lung tissue samples from children who had died from severe respiratory infections during 1985-2005. Immunoperoxidase assay was performed to detect the viruses that were most commonly associated with respiratory tract infections: influenza virus A (FLU A), influenza virus B (FLU B), respiratory syncytial virus (RSV), adenovirus (AdV) and parainfluenza virus (PIV) types 1, 2 and 3. RESULTS: Viruses were detected in 71 (35.5%) cases. Most positive cases were observed in children younger than 6 months. In 42.3% of cases, only one virus was detected: 11 (36.7%) RSV; 7 (23.3%) AdV; 4 (13.3%) PIV2; 3 (10%) FLU A; 2 (6.7%) FLU B; 2 (6.7%) PIV3; and 1 (3.3%) PIV1. Co-infection with more than one virus was observed in 41 (57.7%) cases. No positive correlations were observed between the presence of viral antigens and seasonality of the infection, sex, age or histopathological findings. CONCLUSIONS: Non-pandemic seasonal respiratory viruses are involved in a significant number of deaths in paediatric patients; these findings highlight the importance of laboratory investigation of these agents in patients hospitalised with severe acute respiratory infections.

Respiratory viruses in pediatric necropsies: an immunohistochemical study.

Infections of the respiratory system are responsible for the majority of hospitalizations and deaths in pediatric patients in developing countries. We selected 177 necropsies of pediatric patients who died as a result of serious respiratory infections. The histopathological findings and epidemiological data were reviewed, and lung tissue samples were separated for immunohistochemistry testing. Conventional immunohistochemistry techniques were used to detect viral antigens in formalin-fixed, paraffin-embedded (FF-PE) lung tissue samples using a pool of monoclonal antibodies against respiratory viruses (respiratory syncytial virus, influenza A and B, adenovirus, and parainfluenza 1, 2, and 3 viruses) as primary antibodies. The histopathological findings were classified into bronchopneumonia (BCP) and interstitial pneumonitis (IP) patterns. The immunohistochemistry results were compared with histopathological patterns and epidemiological data. Positive results for viruses were found in 34% and 62.5% of the BCP and IP cases, respectively. Males and infants below 1 year of age were more frequent in the group that had positive results for viruses. Acute enteritis was the main cause of hospitalization and sepsis the most frequent cause of death in this group. A clear seasonal distribution was observed, with the majority of cases occurring in the 2nd and 3rd trimesters (autumn and winter) of each year in the period studied. Immunohistochemistry is an affordable and easy-to-perform method for viral-antigen detection in FF-PE tissue samples. Although BCP is a classic histopathological pattern found in bacterial infections, it is possible that children with serious respiratory infections had concomitant viral and bacterial infections, regardless of their previous immunologic state.