Breastfeeding by chikungunya virus-infected dams confers resistance to challenge in the offspring.

Vertical transmission of Chikungunya virus (CHIKV) has been reported in humans, but the transmission routes have not been completely understood, and experimental animal models are needed to enable detailed investigation of the transmission and pathogenesis of congenital infections. The intertwining of immune response and virus components at the gestation/breastfeeding interfaces between mother and fetus/newborn may have effects during the offspring development. An experimental model of CHIKV was established by infecting pregnant BALB/c female mice that enabled confirmation that dams inoculated up to the 10th gestational day transmit CHIKV transplacentally to approximately 8.4% of the fetuses, resulting in severe teratogenic effects. CHIKV neutralizing antibodies were detected in sera from adult mice born to healthy females and breastfed by CHIKV-infected dams, while no neutralization was detected in sera from animals born to CHIKV-infected dams. Moreover, adult mice born to healthy dams and cross-fostered for breastfeeding by CHIKV-infected dams were resistant to challenge with CHIKV on the 90th day after birth. The animals also had reduced viral loads in brain and spleen as compared to controls. There was expression of fluorescent CHIKV non-structural protein, and detection of viral RNA by RT-PCR in breast tissue from infected dams. CHIKV RNA and proteins were also detected in breast milk retrieved from the stomachs of recently fed newborns. The experimental results were also complemented by the finding of CHIKV RNA in 6% of colostrum samples from healthy lactating women in a CHIKV-endemic area. Breastfeeding induces immune protection to challenge with CHIKV in mice.

Human Respiratory Syncytial Virus Infection in a Human T Cell Line Is Hampered at Multiple Steps.

Human respiratory syncytial virus (HRSV) is the most frequent cause of severe respiratory disease in children. The main targets of HRSV infection are epithelial cells of the respiratory tract, and the great majority of the studies regarding HRSV infection are done in respiratory cells. Recently, the interest on respiratory virus infection of lymphoid cells has been growing, but details of the interaction of HRSV with lymphoid cells remain unknown. Therefore, this study was done to assess the relationship of HRSV with A3.01 cells, a human CD4+ T cell line. Using flow cytometry and fluorescent focus assay, we found that A3.01 cells are susceptible but virtually not permissive to HRSV infection. Dequenching experiments revealed that the fusion process of HRSV in A3.01 cells was nearly abolished in comparison to HEp-2 cells, an epithelial cell lineage. Quantification of viral RNA by RT-qPCR showed that the replication of HRSV in A3.01 cells was considerably reduced. Western blot and quantitative flow cytometry analyses demonstrated that the production of HRSV proteins in A3.01 was significantly lower than in HEp-2 cells. Additionally, using fluorescence in situ hybridization, we found that the inclusion body-associated granules (IBAGs) were almost absent in HRSV inclusion bodies in A3.01 cells. We also assessed the intracellular trafficking of HRSV proteins and found that HRSV proteins colocalized partially with the secretory pathway in A3.01 cells, but these HRSV proteins and viral filaments were present only scarcely at the plasma membrane. HRSV infection of A3.01 CD4+ T cells is virtually unproductive as compared to HEp-2 cells, as a result of defects at several steps of the viral cycle: Fusion, genome replication, formation of inclusion bodies, recruitment of cellular proteins, virus assembly, and budding.

IL-33 and ST2 as predictors of disease severity in children with viral acute lower respiratory infection.

BACKGROUND: Mechanisms influencing severity of acute lower respiratory infection (ALRI) in children are not established. We aimed to assess the role of inflammatory markers and respiratory viruses in ALRI severity. METHODS: Concentrations of interleukin(IL)-33, soluble suppression of tumorigenicity (sST)2, IL-1ß, tumor necrosis factor α, IL-4, IL-6 and IL- 8 and types of respiratory viruses were evaluated in children at the first and fifth days after hospital admission. Disease severity was defined as need for mechanical ventilation. RESULTS: Seventy-nine children <5 years-old were included; 33(41.8%) received mechanical ventilation. No associations between virus type, viral load or co-detections and severity of disease were observed. Detection of IL-33 and sST2 in nasopharyngeal aspirates (NPA) on admission were associated with higher risk for mechanical ventilation (RR = 2.89 and RR = 4.57, respectively). IL-6 and IL-8 concentrations were higher on Day 5 in mechanically ventilated children. IL-6 NPA concentrations decreased from Day 1 to Day 5 in children who did not receive mechanical ventilation. Increase in sST2 NPA concentrations from Day 1 to Day 5 was associated with longer hospital length of stay (p < 0.01). CONCLUSIONS: An exacerbated local activation of the IL-33/ST2 axis and persistently high sST2 concentrations over time were associated with severity of viral ALRI in children.

Human adenovirus replication and persistence in hypertrophic adenoids and palatine tonsils in children.

The role of human adenovirus (HAdV) infection in different acute diseases, such as febrile exudative tonsillitis, conjunctivitis, and pharyngoconjunctival fever is well established. However, the relationships, if any, of HAdV persistence and reactivation in the development of the chronic adenotonsillar disease is not fully understood. The present paper reports a 3-year cross-sectional hospital-based study aimed at detecting and quantifying HAdV DNA and mRNA of the HAdV hexon gene in adenoid and palatine tonsil tissues and nasopharyngeal secretions (NPS) from patients with adenotonsillar hypertrophy or recurrent adenotonsillitis. HAdV C, B, and E were detectable in nearly 50% of the patients, with no association with the severity of airway obstruction, nor with the presence of recurrent tonsillitis, sleep apnea or otitis media with effusion (OME). Despite the higher rates of respiratory viral coinfections in patients with HAdV, the presence of other viruses, including DNA and RNA viruses, had no association with HAdV replication or shedding in secretions. Higher HAdV loads in adenoids showed a significant positive correlation with the presence of sleep apnea and the absence of OME. Although this study indicates that a significant proportion (~85%) of individuals with chronic adenotonsillar diseases have persistent nonproductive HAdV infection, including those by HAdV C, B, and E, epithelial and subepithelial cells in tonsils seem to be critical for HAdV C production and shedding in NPS in some patients, since viral antigen was detected in these regions by immunohistochemistry in four patients, all of which were also positive for HAdV mRNA detection.