The protection quest is a primary key to sharing the neutralizing antibody response to cover against all emerging VOCs based on BIV1-CovIran studies.

Over time, the antigenic evolution of emerging variants of SARS-CoV-2 has demanded the development of potential protective vaccines. Administration of additional doses of current vaccines based on the WT spike protein may boost immunity, but their effectiveness has dwindled for patients with more recent variants. Here, we studied the neutralization activity of post-WT strain-based vaccination and a structural simulation in-silico based on the interactions of the RBD-hACE2 as the key to initiating infection among the VOCs of SARS-CoV-2. Our data display shows that WT sera showed a markedly greater reduction in Delta and Omicron, suggesting that the Wuhan-based vaccines may be more susceptible to breakthrough and new VOCs. According to the MD simulation, mutations of Omicron result in a significant change in the variant charge distribution throughout the binding interface that consequently alters the critical interface electrostatic potential in comparison to other variants. This observation provides new insights into immunization policy and next-generation vaccine development.

Validation of a SARS-CoV-2 Surrogate Virus Neutralization Test in Recovered and Vaccinated Healthcare Workers.

Vaccination against COVID-19 is the main public health approach to fight against the pandemic. The Spike (S) glycoprotein of SARS-CoV-2 is the principal target of the neutralizing humoral response. We evaluated the analytical and clinical performances of a surrogate virus neutralization test (sVNT) compared to conventional neutralization tests (cVNTs) and anti-S eCLIA assays in recovered and/or vaccinated healthcare workers. Our results indicate that sVNTs displayed high specificity and no cross-reactivity. Both eCLIA and sVNT immunoassays were good at identifying cVNT serum dilutions ≥1:16. The optimal thresholds when identifying cVNT titers ≥1:16, were 74.5 U/mL and 49.4 IU/mL for anti-S eCLIA and sVNT, respectively. Our data show that neutralizing antibody titers (Nab) differ from one individual to another and may diminish over time. Specific assays such as sVNTs could offer a reliable complementary tool to routine anti-S serological assays.

Differences and similarities between mesenchymal stem cell and endothelial progenitor cell immunoregulatory properties against T cells.

Bone-marrow-derived mesenchymal stem cells and endothelial progenitor cells have some interesting biological properties that make them unique for cell therapy of degenerative and cardiovascular disorders. Although both cell populations have been already studied and used for their regenerative potentials, recently their special immunoregulatory features have brought much more attention. Mesenchymal stem cells and endothelial progenitor cells have both proangiogenic functions and have been shown to suppress the immune response, particularly T cell proliferation, activation, and cytokine production. This makes them suitable choices for allogeneic stem cell transplantation. Nevertheless, these two cells do not have equal immunoregulatory activities. Many elements including their extraction sources, age/passage, expression of different markers, secretion of bioactive mediators, and some others could change the efficiency of their immunosuppressive function. However, to our knowledge, no publication has yet compared mesenchymal stem cells and endothelial progenitor cells for their immunological interaction with T cells. This review aims to specifically compare the immunoregulatory effect of these two populations including their T cell suppression, deactivation, cytokine production, and regulatory T cells induction capacities. Moreover, it evaluates the implications of the tumor necrosis factor alpha-tumor necrosis factor receptor 2 axis as an emerging immune checkpoint signaling pathway controlling most of their immunological properties.

Antiviral screening of four plant extracts against acyclovir resistant herpes simplex virus type-1.

Herpes simplex virus type 1 (HSV-1) causes serious infections particularly in immunocompromised patients. Methanolic extract of four plants were evaluated for their anti-viral effects against acyclovir resistant HSV-1 in HeLa cell line. The 50% cytotoxic concentration (CC50) as well as the effective minimal cytotoxic concentration of each plant extract were evaluated by MTT assay. Antiviral effects of the plant extracts on HSV-1 were examined at different concentrations of the extract. The effective minimal cytotoxic concentration was evaluated at different times of virus replication after infection. Virus titration was assessed by tissue culture infectious dose 50 (TCID50) method. Among the 4 plant extracts evaluated only Mentha pulegium L. extract was shown to exert the highest antiviral activity, with selectivity index (SI) 10.25. Direct treatment of HSV-1 with Mentha pulegium L. extract resulted in 1.7 log10 TCID50 reduction in virus titers after one hour. The highest reduction in HSV-1 infectivity was obtained 1 hour after the infection of the cells with virus resulting in 2.1 log10 TCID50 reduction as compared to the control. The antiviral effects of Mentha pulegium L. extract on HSV-1 after virus infection was more remarkable than the virucidal activity.