Hamsters Protected from SARS-CoV-2 Delta Variant Challenge after Two Doses of Adjuvanted SARS-CoV-2 Recombinant Spike Protein (S-2P) and One Dose of Beta S-2P.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern negatively impact the effectiveness of vaccines. In this study, we challenge hamsters with the delta variant after 2- or 3-dose inoculations with SARS-CoV-2 vaccines constructed from stabilized prefusion spike proteins (S-2P) of Wuhan (W) and beta (B) variants. Compared to 3 doses of W S-2P, 2 doses of W S-2P followed by a third dose of B S-2P induced the highest neutralizing antibody titer against live SARS-CoV-2 virus and enhanced neutralization of omicron variant pseudovirus. Reduced lung live virus titer and pathology suggested that all vaccination regimens protect hamsters from SARS-CoV-2 delta variant challenge.

Evaluating the Neutralizing Ability of a CpG-Adjuvanted S-2P Subunit Vaccine Against Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Variants of Concern.

BACKGROUND: Variants of concern (VoCs) have the potential to diminish the neutralizing capacity of antibodies elicited by vaccines. MVC-COV1901 is a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine consisting of recombinant prefusion stabilized spike protein S-2P adjuvanted with CpG 1018 and aluminum hydroxide. We explored the effectiveness of MVC-COV1901 against the VoCs. METHODS: Serum samples were taken from rats and phase 1 clinical trial human subjects immunized with a low, medium, or high dose of MVC-COV1901. The neutralizing titers of serum antibodies were assayed with pseudoviruses coated with the SARS-CoV-2 spike protein of the wild-type (WT), D614G, Alpha, or Beta variants. RESULTS: Rats vaccinated twice with vaccine containing high doses of antigen retained high levels of neutralization activity against the Beta variant, albeit with a slight reduction compared to WT. After the third dose, neutralizing titers against the Beta variant were noticeably enhanced regardless of the amount of antigen used for immunization. In humans, vaccinated phase 1 subjects still showed appreciable neutralization abilities against the D614G, Alpha, and Beta variants, although neutralizing titers were significantly reduced against the Beta variant. CONCLUSIONS: Two doses of MVC-COV1901 were able to elicit neutralizing antibodies against SARS-CoV-2 variants with an overall tendency of inducing higher immune response at a higher dose level. The neutralizing titers to the Beta variant in rats and humans were lower than those for WT and the Alpha variant. An additional third dose in rats was able to partially compensate for the reduction in neutralization against the Beta variant. We have demonstrated that immunization with MVC-COV1901 was effective against VoCs.

Development of CpG-adjuvanted stable prefusion SARS-CoV-2 spike antigen as a subunit vaccine against COVID-19.

The COVID-19 pandemic is a worldwide health emergency which calls for an unprecedented race for vaccines and treatment. In developing a COVID-19 vaccine, we applied technology previously used for MERS-CoV to produce a prefusion-stabilized SARS-CoV-2 spike protein, S-2P. To enhance immunogenicity and mitigate the potential vaccine-induced immunopathology, CpG 1018, a Th1-biasing synthetic toll-like receptor 9 (TLR9) agonist was selected as an adjuvant candidate. S-2P in combination with CpG 1018 and aluminum hydroxide (alum) was found to be the most potent immunogen and induced high titer of neutralizing antibodies in sera of immunized mice against pseudotyped lentivirus reporter or live wild-type SARS-CoV-2. In addition, the antibodies elicited were able to cross-neutralize pseudovirus containing the spike protein of the D614G variant, indicating the potential for broad spectrum protection. A marked Th1 dominant response was noted from cytokines secreted by splenocytes of mice immunized with CpG 1018 and alum. No vaccine-related serious adverse effects were found in the dose-ranging study in rats administered single- or two-dose regimens of S-2P combined with CpG 1018 alone or CpG 1018 with alum. These data support continued development of CHO-derived S-2P formulated with CpG 1018 and alum as a candidate vaccine to prevent COVID-19 disease.

The Value of 18F-FDG PET/CT Imaging Combined With Pretherapeutic Ki67 for Early Prediction of Pathologic Response After Neoadjuvant Chemotherapy in Locally Advanced Breast Cancer.

To evaluate the value of F-fluorodeoxyglucose-positron emission tomography/computed tomography (F-FDG PET/CT) and pretherapeutic Ki67 in predicting pathologic response in locally advanced breast cancer (LABC) after neoadjuvant chemotherapy (NAC).As a training set, total 301 LABC patients treated with NAC were retrospectively analyzed to evaluate the potential predictive value of pretherapeutic Ki67 for pathologic complete response (pCR) after NAC. Another 60 LABC patients were prospectively included as a validation set to evaluate the value of Ki67 combined PET/CT as pCR predictors. Ki67 was assessed in pretherapy core needle biopsy specimens and PET/CT scans were performed at baseline (before initiating NAC), after the 2nd, and 4th cycle of NAC. Maximum standardized uptake value (SUVmax) and its changes relative to baseline (ΔSUVmax%) were used as parameters of PEC/CT.In the training set, Ki67 was a predictor of pCR to NAC, with area under the curve (AUC) of 0.624 (P = 0.003) in receiver-operating characteristic (ROC) analysis. In the validation set, Ki67 alone did not show significant value in predicting pCR in the validation set. ΔSUVmax% after then 2nd or 4th course are predictors of pCR to NAC with the AUC of 0.774 (P = 0.002) and 0.791 (P = 0.002), respectively. When combined with ΔSUVmax% after the 2nd and 4th course NAC, Ki67 increased the value of ΔSUVmax% in predicting pCR with the AUC of 0.824 (P = 0.001). Baseline SUVmax and after 2nd, 4th course NAC had no predictive value for pCR, but SUVmax after the 2nd and 4th course showed remarkable predictive value for nonpathologic response (Grade 1 in Miller-Payne Grading System) with the AUC of 0.898 (P = 0.0001) and 0.801 (P = 0.003).Both PET/CT and Ki67 can predict pCR to NAC in LABC patients in the early phases of treatment. PET/CT combined Ki67 is a better pCR predictor for response to NAC. This helps the physician to predict the probability of pCR, and facilitates the optimization of individual treatment plan in case of ineffective and/or excessive chemotherapy.

Pacific oyster-derived polysaccharides enhance antigen-specific T helper (Th)1 immunity in vitro and in vivo.

Bacterial and fungal polysaccharides are well known as being immunoactive. However, evidence pertaining to the immunomodulatory activity of polysaccharides derived from animal origins is scarce. This study investigated the effects of an extract of oyster (Crassostrea gigas) polysaccharides (OPS) on antigen-specific T-cell immunity. For in vitro studies, ovalbumin (OVA)-primed splenocytes were exposed to OPS and re-stimulated with OVA in culture to induce antigen-specific responses. For in vivo studies, mice were administered with OPS prior to OVA sensitization, and the functionality of their splenocytes was examined. Direct exposure of OVA-primed splenocytes to OPS (10-500 µg/mL) resulted in a marked enhancement of the cell metabolic activity and proliferation. Exposure to OPS also augmented the expression of the T helper (Th)1 cytokine interferon (IFN)-γ, whereas the Th2 cytokine interleukin-4 was suppressed. The enhancement of antigen-specific IFN-γ expression was further demonstrated in splenocytes of mice administered with OPS (100 and 200 mg/kg). Moreover, OPS enhanced the mRNA expression of T-bet, a transcription factor governing the development of Th1 cells, by splenocytes. Taken together, these results demonstrated that OPS modulated antigen-specific T cell responses, including antigen-induced splenocyte proliferation and T-cell cytokine expression. In addition, OPS polarized the Th1/Th2 immunobalance toward the Th1-dominant direction, which may be attributed to the up-regulation of Th1 cell development.

Prebiotic effect of diosgenin, an immunoactive steroidal sapogenin of the Chinese yam.

This study investigated the effect of diosgenin, a yam-derived phytochemical, on the growth of enteric lactic acid bacteria (LAB). The in vivo effect of diosgenin on the density of intestinal flora was examined in a murine model of food allergy. Oral administration with diosgenin markedly restored the diminished density of faecal LAB associated with allergic reactions. The direct effect of diosgenin and several structure-related steroidal compounds on the growth of faecal anaerobes isolated from diosgenin-administered mice was also investigated. The presence of diosgenin significantly enhanced the growth of Lactobacillus murinus and Lactobacillus reuteri, but not enterococci. Structure-activity relationship analysis showed that the prebiotic activity of steroidal sapogenins might require structural elements of the C5-C6 double bond and intact E- and F-rings. Collectively, these results indicate that steroidal sapogenins may be a novel class of prebiotics to LAB.