SARS-CoV-2 has caused a global pandemic, infecting millions of people. An effective preventive vaccine against this virus is urgently needed. Here, we designed and developed a novel formulated recombinant receptor-binding domain (RBD) nucleocapsid (N) recombinant vaccine candidates. The RBD and N were separately expressed in E. coli and purified using column chromatography. The female Balb/c mice were immunized subcutaneously with the combination of purified RBD and N alone or formulated with saponin adjuvant in a two-week interval in three doses. Neutralization antibody (Nabs) titers against the SARS-CoV-2 were detected by a Surrogate Virus Neutralization (sVNT) Test. Also, total IgG and IgG1, and IgG2a isotypes and the balance of cytokines in the spleen (IFN-γ, Granzyme B, IL-4, and IL-12) were measured by ELISA. The percentages of CD4+ and CD8+ T cells were quantified by flow cytometry. The lymphoproliferative activity of restimulated spleen cells was also determined. The findings showed that the combination of RBD and N proteins formulated with saponin significantly promoted specific total IgG and neutralization antibodies, elicited robust specific lymphoproliferative and T cell response responses. Moreover, marked increase in CD4+ and CD8+ T cells were observed in the adjuvanted RBD and N vaccine group compared with other groups. The results suggest that the formulations are able to elicit a specific long-lasting mixed Th1/Th2 balanced immune response. Our data indicate the significance of the saponin-adjuvanted RBD/N vaccine in the design of SARS-CoV-2 vaccines and provide a rationale for the development of a protective long-lasting and strong vaccine.

Background: Helicobacter pylori (H. pylori) is identified as the most frequent agent of bacterial infections in humans which can cause various gastrointestinal diseases. This pathogen has infected approximately half of the world’s population, and its outbreak has varied across different regions. The purpose of this study was to estimate the H. pylori infection prevalence amongst patients in Fardis county, Alborz province, Iran, using noninvasive methods. Methods: A total of 5677 patients were analyzed from September 2020 to October 2021 to detect H. pylori by the use of enzyme-linked immunosorbent assay (ELISA) IgG, IgA, and IgM tests, stool antigen test (SAT), and urea breath test (UBT). Results: Of 5677 patients, 3486 (61.4%) were female and 2191 (38.6%) were male with the mean age of 38.82 ± 18.289 years old. The overall rate of H. pylori infection positive was 31.46%, and the serological tests were the most prescribed types of tests. The IgG test and then SAT detected the most positive cases. Further, the infection rate was significantly associated with age. Except for the case of IgM, which was higher in females compared to males, no significant difference was found between gender and bacteria outbreak. Conclusions: This study indicated a decline in H. pylori infection prevalence compared with the prior survey conducted at this center. However, its rate amongst the patients referring to Fardis laboratory is still high.