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Virus respiratorio sincitial, metapneumovirus y virus parainfluenza humanos: cuadro clinico y fisiopatologia.

ABSTRACT: El VRSh causa la mayor parte de las bronquiolitis del lactante, infecciones respiratorias bajas que provocan trastornos respiratorios obstructivos y sibilancias. Los factores relacionados con las características del paciente (prematuridad, enfermedades asociadas, predisposición genética), con el virus (VRShA, genotipo, etc.) o el ambiente (contaminación, tabaquismo, etc.) son determinantes en la génesis de las bronquiolitis y determinan su gravedad. La mortalidad de la bronquiolitis es del 0,005-0,2% dependiendo de las características del paciente. No se conoce la fisiopatología de la bronquiolitis por VRSh. El papel directo del virus sobre el epitelio, la inmadurez del pulmón del lactante y, como se ha demostrado recientemente, el papel de la reacción inflamatoria, son factores destacados. También es probable que haya mecanismos inmunopatológicos (anticuerpos IgE, respuesta CD4+ Th2, etc.) que intervengan en ciertas bronquiolitis. La inmunidad anti-VRSh nunca llega a ser completa y las reinfecciones son frecuentes en los niños pequeños y las personas de edad avanzada, en quienes la infección por el VRSh representa aproximadamente el 5% de las afecciones respiratorias bajas. Con frecuencia se presentan con un cuadro de neumopatía infecciosa atípica con signos de bronquiolitis. Las infecciones debidas al VPIh3 suelen manifestarse por bronquiolitis, y las infecciones secundarias al VPIh1 y al 2 por laringotraqueítis. No se conoce bien la expresión clínica de las infecciones por VPIh4. El MPVh causa bronquiolitis comparables en todos sus aspectos a las que origina el VRSh.

SUBMITTER: Freymuth F

PROVIDER: S-EPMC7159021 | biostudies-literature | 2007

REPOSITORIES: biostudies-literature

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Project description:BackgroundHuman respiratory syncytial virus (HRSV), and to a lesser extent human metapneumovirus (HMPV) and human parainfluenza virus type 3 (HPIV3), re-infect symptomatically throughout life without antigenic change, suggestive of incomplete immunity. One causative factor is thought to be viral interference with dendritic cell (DC)-mediated stimulation of CD4+ T cells.Methodology, principal findingsWe infected human monocyte-derived DC with purified HRSV, HMPV, HPIV3, or influenza A virus (IAV) and compared their ability to induce activation and proliferation of autologous CD4+ T cells in vitro. IAV was included because symptomatic re-infection without antigenic change is less frequent, suggesting that immune protection is more complete and durable. We examined virus-specific memory responses and superantigen-induced responses by multiparameter flow cytometry. Live virus was more stimulatory than inactivated virus in inducing DC-mediated proliferation of virus-specific memory CD4+ T cells, suggesting a lack of strong suppression by live virus. There were trends of increasing proliferation in the order: HMPV<HRSV<HPIV3<IAV, and greater production of interferon-γ and tumor necrosis factor-α by proliferating cells in response to IAV, but differences were not significant. Exposure of DC to HRSV, HPIV3, or IAV reduced CD4+ T cell proliferation in response to secondary stimulus with superantigen, but the effect was transitory and greatest for IAV. T cell cytokine production was similar, with no evidence of Th2 or Th17 skewing.Conclusions, significanceUnderstanding the basis for the ability of HRSV in particular to symptomatically re-infect without significant antigenic change is of considerable interest. The present results show that these common respiratory viruses are similar in their ability to induce DC to activate CD4+ T cells. Thus, the results do not support the common model in which viral suppression of CD4+ T cell activation and proliferation by HRSV, HMPV, and HPIV3 is a major factor in the difference in re-infectability compared to IAV.

Project description:BackgroundRespiratory disease is a major cause of morbidity and mortality; however, surveillance for circulating respiratory viruses is passive and biased. Wastewater-based epidemiology has been used to understand SARS-CoV-2, influenza A, and respiratory syncytial virus (RSV) infection rates at a community level but has not been used to investigate other respiratory viruses. We aimed to use wastewater-based epidemiology to understand community viral respiratory infection occurrence.MethodsA retrospective wastewater-based epidemiology surveillance study was carried out at a large wastewater treatment plant located in California, USA. Using droplet digital RT-PCR, we measured RNA concentrations of influenza A and influenza B viruses, RSV A and RSV B, parainfluenza (1-4) viruses, rhinovirus, seasonal coronaviruses, and metapneumovirus in wastewater solids three times per week for 17 months (216 samples) between Feb 1, 2021, and June 21, 2022. Novel probe-based RT-PCR assays for non-influenza viral targets were developed and validated. We compared viral RNA concentrations to positivity rates for viral infections from clinical specimens submitted to California Sentinel Clinical Laboratories (sentinel laboratories) to assess concordance between the two datasets.FindingsWe detected RNA from all tested viruses in wastewater solids. Human rhinovirus (median concentration 4300 [0-9500] copies per gram dry weight) and seasonal human coronaviruses (35 000 [17 000-56 000]) were found at the highest concentrations. Concentrations of viral RNA correlated significantly and positively with positivity rates of associated viral diseases from sentinel laboratories (tau 0·32-0·57, p<0·0009); the only exceptions were influenza B and RSV A, which were rarely detected in wastewater solids. Measurements from wastewater indicated coronavirus OC43 dominated the seasonal human coronavirus infections whereas parainfluenza 3 dominated among parainfluenza infections during the study period. Concentrations of all tested viral RNA decreased noticeably after the omicron BA.1 surge suggesting a connection between changes in human behaviour during the surge and transmission of all respiratory viruses.InterpretationWastewater-based epidemiology can be used to obtain information on circulation of respiratory viruses at a localised, community level without the need to test many individuals because a single sample of wastewater represents the entire contributing community. Results from wastewater can be available within 24 h of sample collection, generating real time information to inform public health responses, clinical decision making, and individual behaviour modifications.FundingCDC Foundation.

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Virus respiratorio sincitial, metapneumovirus y virus parainfluenza humanos: cuadro clinico y fisiopatologia.

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