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During the COVID-19 pandemic, the early emergence of viral variants repeatedly undermined the effects of vaccination. Our aim here is to explore strategies for improving spike vaccine gene antigenicity by merging mutations from different variants of concern (VOCs) in a single vaccine gene. To this end, newly developed recombinant vaccine genes were designed, cloned into adenoviral vectors, and applied to C57BL/6 mice; then, serum-neutralizing antibodies against the wildtype SARS-CoV-2 strains were determined in neutralization assays. The merger of mutations from different variants of concern (alpha, beta, gamma, and delta) in a single recombinant spike-based vaccine gene provided a substantial improvement in neutralizing immunity to all variants of concern, including the omicron strains. To date, only unmodified spike genes of the original SARS-CoV-2 Wuhan strain (B.1) or dominant variants (BA.1, BA.5, and XBB.1.5) have been used as vaccine genes. The employment of unmodified vaccine genes is afflicted by limited cross-protection among variant strains. In contrast, recombinant vaccine genes that combine mutations from different strains in a single gene hold the potential to broaden and improve immune protection and might help to reduce the need for frequent vaccine adaptations in the future.

Vaccines play a critical role in combating the COVID-19 pandemic. Future control of the pandemic requires improved vaccines with high efficacy against newly emerging SARS-CoV-2 variants and the ability to reduce virus transmission. Here we compare immune responses and preclinical efficacy of the mRNA vaccine BNT162b2, the adenovirus-vectored spike vaccine Ad2-spike and the live-attenuated virus vaccine candidate sCPD9 in Syrian hamsters, using both homogeneous and heterologous vaccination regimens. Comparative vaccine efficacy was assessed by employing readouts from virus titrations to single-cell RNA sequencing. Our results show that sCPD9 vaccination elicited the most robust immunity, including rapid viral clearance, reduced tissue damage, fast differentiation of pre-plasmablasts, strong systemic and mucosal humoral responses, and rapid recall of memory T cells from lung tissue after challenge with heterologous SARS-CoV-2. Overall, our results demonstrate that live-attenuated vaccines offer advantages over currently available COVID-19 vaccines., (© 2023. The Author(s).)

With the exception of inactivated vaccines, all SARS-CoV-2 vaccines currently used for clinical application focus on the spike envelope glycoprotein as a virus-specific antigen. Compared to other SARS-CoV-2 genes, mutations in the spike protein gene are more rapidly selected and spread within the population, which carries the risk of impairing the efficacy of spike-based vaccines. It is unclear to what extent the loss of neutralizing antibody epitopes can be compensated by cellular immune responses, and whether the use of other SARS-CoV-2 antigens might cause a more diverse immune response and better long-term protection, particularly in light of the continued evolution towards new SARS-CoV-2 variants. To address this question, we explored immunogenicity and protective effects of adenoviral vectors encoding either the full-length spike protein (S), the nucleocapsid protein (N), the receptor binding domain (RBD) or a hybrid construct of RBD and the membrane protein (M) in a highly susceptible COVID-19 hamster model. All adenoviral vaccines provided life-saving protection against SARS-CoV-2-infection. The most efficient protection was achieved after exposure to full-length spike. However, the nucleocapsid protein, which triggered a robust T-cell response but did not facilitate the formation of neutralizing antibodies, controlled early virus replication efficiently and prevented severe pneumonia. Although the full-length spike protein is an excellent target for vaccines, it does not appear to be the only option for future vaccine design.

Purpose: The cell surface glycoprotein Mesothelin is overexpressed in ovarian, fallopian tube, endometrial, cervical and primary peritoneal cancer and, therefore, might become a particular interesting tumor target in gynecologic oncology. However, even in malignant tumors of the same entity the level of Mesothelin expression varies between individuals, hence it can be expected that the response to Mesothelin-targeting therapies will be variable as well. In this study we explored the therapeutic potency of a novel anti-Mesothelin antibody-drug conjugate (Anetumab ravtansine) as a function of Mesothelin expression in the targeted tumor cells., Methods: Anti-tumor activity studies were performed in human uterine xenograft tumor models that express Mesothelin at high, moderate or low levels. The antibody-drug conjugate (ADC) was applied in varying doses ranging from 2 to 15 mg/kg at variable intervals in tumor bearing SCID/beige mice and the impact on tumor growth was monitored., Results: The therapeutic response to the anti-Mesothelin ADC correlated closely with the level of Mesothelin expression in tumor cells. Within the applied dose levels complete tumor regression was achieved only in tumors which expressed Mesothelin at particularly high levels (Hela cell tumors). The application of high anti-Mesothelin ADC doses less frequently was more efficious than giving lower doses at a higher frequency., Conclusion: The studies confirm the great therapeutic potential of Anetumab ravtansine. However, a favorable treatment outcome requires strong Mesothelin expression in tumor cells. Future clinical trials may benefit from a more rigorous selection of appropriate patients based on the level of Mesothelin expression in their tumor tissue. If, in addition, it is possible to better control side effects by introducing protective measures and by doing so to increase the maximum tolerated dose, Anetumab ravtansine has the potency to become a valuable therapeutic tool, especially in the field of gynecological oncology.

Purpose: The cell surface glycoprotein Mesothelin is overexpressed in several tumor entities and novel immune-based therapies are currently under the early clinical evaluation for the treatment of malignant pleura mesothelioma, ovarian cancer, and pancreatic cancer. Cervical cancer has not been recognized as a suitable target for Mesothelin-directed immune therapies so far., Methods: To exploit a possible role of Mesothelin in cervical cancer treatment, we analysed Mesothelin expression in 79 cervical carcinomas and aligned expressions patterns with tumor growth parameters. A novel anti-Mesothelin drug conjugate (Anetumab Ravtansine) was applied for dose-efficiency studies in a Mesothelin positive tumor model for cervical cancer in Scid mice., Results: In more than three-quarters (77%) of cervical adenocarcinomas, Mesothelin was expressed to high levels. Among squamous cell carcinomas of the cervix uteri expression levels were lower and expression patterns were less intense, but still ranged between 50-60% (57%). A significant correlation between Mesothelin expression levels and tumor grade, metastatic behaviour, and lymph- or hemangiosis was not found. The novel anti-Mesothelin-drug conjugate (Anetumab Ravtansine) showed a substantial dose-dependent therapeutic efficiency in a xenotransplant model for cervical cancer in SCID mice (hela cell tumors). Applying the ADC at a dose of 10 mg/kg twice weekly induced complete tumor regression in 88% of animals within 6 weeks., Conclusions: Mesothelin should be taken into account as a target in cervical cancer therapy and histological determination of Mesothelin expression should be considered in routine diagnostics of cervical carcinomas.

Purpose: The identification of novel cell lines which combine the most important properties of mucosal membranes in terms of drug absorption, transmembrane transport and mucus secretion can help to establish improved and meaningful test systems for pharmacological and infectiological studies., Methods: We have established a novel mucus secreting tumor cell line (Cx-03) derived from a female patient who underwent radical hysterectomy after diagnosis of a large malignant carcino sarcoma (Muellerian mixed tumor). Via xenotransplantation in SCID beige mice, recultivation and subcloning a stable cell line was established from primary tumor cells., Results: Human origin and novelty of the cell line was determined by karyotype analysis and STR fingerprint. During growth cells produce considerable amounts of a PAS positive viscoelastic mucus. Immunostaining revealed expression of mucins and the mucin modifier CLCA1. We demonstrate in initial electrophysiological experiments that confluent, polarized monolayers of Cx-03 are formed (on PCF-filter supports) that exhibit stable electrical resistance (> 600 Ω cm 2 ). Confluent Cx-03 monolayers express barrier-forming tight junction proteins claudin-1 and -4 which co-localize with zonula occludens protein-1 (ZO-1) at cell-cell contacts., Conclusions: Mucus secretion is a rare property among mammalian cell lines. In combination with its ability to form polarized monolayers Cx-03 might contribute as a novel cell based model for drug absorption, transport and barrier studies.