Search

Pandemic outbreaks of viruses such as influenza virus or SARS-CoV-2 are associated with high morbidity and mortality and thus pose a massive threat to global health and economics. Physiologically relevant models are needed to study the viral life cycle, describe the pathophysiological consequences of viral infection, and explore possible drug targets and treatment options. While simple cell culture-based models do not reflect the tissue environment and systemic responses, animal models are linked with huge direct and indirect costs and ethical questions.

In the present study, we were interested in the decline over time of anti SARS-CoV-2 antibodies and SARS-CoV-2 specific T-cell responses after two doses of mRNA vaccines in total and by age group and comorbidity. The second goal was to suggest an immunological correlate for protection on an individual basis and to describe the probability of protection over time after second vaccination.We analysed blood samples from 228 residents (median age 83.8 years) and from 273 Health Care Workers (HCW; median age 49.7 years) of five nursing homes and one home for the elderly with assisted living support. Participants had received two vaccinations. The blood samples were analysed for SARS-CoV-2 specific antibody and T-cell responses. We compared outcomes in the HCW and residents in the respective institutions. No breakthrough infections occurred during the study period. The initial immune responses in the younger participants were about 30 % higher than in the older ones. Over time, all parameters dropped continuously in all groups within the maximum observation period of 232 days. Comorbidities such as coronary heart disease or diabetes mellitus reduced the initial immune responses, regardless of age. In contrast to an almost linear decline in antibody levels, we observed that the interferon-gamma response remained at a constant level between about day 120 and 180, only to decline further thereafter.Based on our data, we propose on an individual level a correlate of protection: Persons who have a neutralizing capacity of 75 % (which would correspond to approx. 200 BAU/ml) and an interferon-gamma response above 200 mIU/ml should be considered to be protected resp. sufficiently immunized.

Influenza is an acute respiratory infection causing high morbidity and mortality in annual outbreaks worldwide. Antiviral drugs are limited and pose the risk of resistance development, calling for new treatment options. IFN-α subtypes are immune-stimulatory cytokines with strong antiviral activities against IAV in vitro and in vivo. However, the clinical use of IFN-α2, the only licensed subtype of this multi-gene family, could not prevent or limit IAV infections in humans. However, the other subtypes were not investigated. Therefore, this study evaluated the induction and antiviral potential of all human IFN-α subtypes during H3N2 IAV infection in human lung explants. We found that subtypes with weak antiviral activities were preferentially induced during IAV infection in human lungs. Intriguingly, non-induced subtypes α16, α5 and α4 suppressed viral replication up to 230-fold more efficiently than α2. Furthermore, our results demonstrate that subtypes with stronger antiviral activities induce higher expression of IAV-specific restriction factors and that MxA expression is a determinant of the subtype-specific antiviral activity towards H3N2 IAV. These results corroborate that IFN-α subtypes exhibit differential antiviral activities and emphasize that subtypes α16, α5 and α4 should be further investigated for the prevention and treatment of severe infections with seasonal H3N2 IAV.

In this study, a nanocomposite of poly (styrene – (ethylene-co-butylene) – styrene) triblock copolymer (SEBS) and an alkyl phosphonium salt-intercalated organic montmorillonite (HMMT) blend was prepared by melt-mixing. The effect of the compatibilizer maleic anhydride-grafted SEBS (SEBS-MA) on structure, morphology and rheological behavior of the SEBS/HMMT nanocomposites were studied. Better dispersion of HMMT domains in SEBS matrix was achieved after adding 7 wt% SEBS-MA, with increased transparency and surface hydrophobicity. The prepared SEBS/HMMT/SEBS-MA nanocomposite displayed significantly improved mechanical, thermal stability and gas barrier properties, which can be attributed to its unique morphology and changed microphase separated structure. These superior properties of the SEBS/nanoclay nanocomposite are important for both biomedical and packing applications.