Neutralizing Antibody Responses against Five SARS-CoV-2 Variants and T Lymphocyte Change after Vaccine Breakthrough Infections from the SARS-CoV-2 Omicron BA.1 Variant in Tianjin, China: A Prospective Study.

Objective: To investigate whether Omicron BA.1 breakthrough infection after receiving the SARS-CoV-2 vaccine could create a strong immunity barrier. Methods: Blood samples were collected at two different time points from 124 Omicron BA.1 breakthrough infected patients and 124 controls matched for age, gender, and vaccination profile. Live virus-neutralizing antibodies against five SARS-CoV-2 variants, including WT, Gamma, Beta, Delta, and Omicron BA.1, and T-lymphocyte lymphocyte counts in both groups were measured and statistically analyzed. Results: The neutralizing antibody titers against five different variants of SARS-CoV-2 were significantly increased in the vaccinated population infected with the Omicron BA.1 variant at 3 months after infection, but mainly increased the antibody level against the WT strain, and the antibody against the Omicron strain was the lowest. The neutralizing antibody level decreased rapidly 6 months after infection. The T-lymphocyte cell counts of patients with mild and moderate disease recovered at 3 months and completely returned to the normal state at 6 months. Conclusion: Omicron BA.1 breakthrough infection mainly evoked humoral immune memory in the original strain after vaccination and hardly produced neutralizing antibodies specific to Omicron BA.1. Neutralizing antibodies against the different strains declined rapidly and showed features similar to those of influenza. Thus, T-lymphocytes may play an important role in recovery.

Inhibition by tyroserleutide (YSL) on the invasion and adhesion of the mouse melanoma cell.

Tyroserleutide (YSL) is an active, low-molecular-weight polypeptide, comprised of three amino acids, that has shown antitumor effects on human hepatocarcinoma BEL-7402 in vitro and in vivo. In this study, we evaluated the inhibition of YSL on invasion and adhesion of the mouse B16-F10 melanoma cell line by injecting B16-F10 cells into the tail veins of C57BL/6 mice to establish an experimental lung metastasis model. YSL inhibited B16-F10 cell metastasis to lung, reducing the number and area of metastasis lesions. When we treated B16-F10 cells with YSL (0.01, 0.1, 1, 10, or 100 microg/mL) in vitro, we found that YSL inhibited the proliferation of B16-F10 cells with a 28.11% rate of inhibition. YSL significantly decreased the adhesiveness of B16-F10 cells to Matrigel with a 29.15% inhibition rate; YSL also significantly inhibited the invasion of B16-F10 cells, producing an inhibition of 35.31%. By analyses with Western blot and real-time RT-PCR, we found that YSL markedly inhibited the expression of ICAM-1 in B16-F10 cells. These data suggest that YSL inhibits the growth, invasion, and adhesion of B16-F10 cells.

[Inhibitory effect of tripeptide compound tyroservaltide on invasion and metastasis of mouse melanoma cell line B16-F10].

BACKGROUND & OBJECTIVE: Tripeptide compound tyroservaltide (YSV) has obvious inhibitory effect on experimental liver cancer. This study was to evaluate the inhibitory effect of YSV on the invasion and metastasis of mouse melanoma cell line B16-F10. METHODS: The cytotoxic effect of YSV on B16-F10 cells was assessed by MTT assay, and the effects of YSV on the adhesiveness and invasiveness of B16-F10 cells were determined using Matrigel and a transwell system. B16-F10 cells were injected into the tail veins of C57BL/6 mice to establish an experimental lung metastasis model, and the effect of YSV on lung metastasis was observed. The effect of YSV on the expression of intercellular adhesion molecule-1 (ICAM-1) in lung tissue was detected by immunohistochemistry. RESULTS: YSV (100 microg/ml, 48 h) inhibited the proliferation of B16-F10 cells, with an inhibitory rate of 24.36%; YSV (100 microg/ml, 24 h) inhibited the adhesiveness of B16-F10 cells to Matrigel, with an inhibitory rate of 36.51%; YSV (10 microg/ml, 48 h) inhibited the invasiveness of B16-F10 cells, with an inhibitory rate of 36.53%; YSV [640 microg.(kg.d)-1] inhibited lung metastasis by B16-F10 cells, with an inhibitory rate of 62.21%. The expression of ICAM-1 in lung tissue was lower in YSV group than in normal saline group. CONCLUSION: YSV can inhibit the growth, invasion, and metastasis of B16-F10 cells.