Fourth dose of microneedle array patch of SARS-CoV-2 S1 protein subunit vaccine elicits robust long-lasting humoral responses in mice.

The COVID-19 pandemic has underscored the pressing need for safe and effective booster vaccines, particularly in considering the emergence of new SARS-CoV-2 variants and addressing vaccine distribution inequalities. Dissolving microneedle array patches (MAP) offer a promising delivery method, enhancing immunogenicity and improving accessibility through the skin's immune potential. In this study, we evaluated a microneedle array patch-based S1 subunit protein COVID-19 vaccine candidate, which comprised a bivalent formulation targeting the Wuhan and Beta variant alongside a monovalent Delta variant spike proteins in a murine model. Notably, the second boost of homologous bivalent MAP-S1(WU + Beta) induced a 15.7-fold increase in IgG endpoint titer, while the third boost of heterologous MAP-S1RS09Delta yielded a more modest 1.6-fold increase. Importantly, this study demonstrated that the administration of four doses of the MAP vaccine induced robust and long-lasting immune responses, persisting for at least 80 weeks. These immune responses encompassed various IgG isotypes and remained statistically significant for one year. Furthermore, neutralizing antibodies against multiple SARS-CoV-2 variants were generated, with comparable responses observed against the Omicron variant. Overall, these findings emphasize the potential of MAP-based vaccines as a promising strategy to combat the evolving landscape of COVID-19 and to deliver a safe and effective booster vaccine worldwide.

Assessing the risk of a clinically significant infection from a Microneedle Array Patch (MAP) product.

Microneedle Array Patches (MAPs) are an emerging dosage form that creates transient micron-sized disruptions in the outermost physical skin barrier, the stratum corneum, to facilitate delivery of active pharmaceutical ingredients to the underlying tissue. Numerous MAP products are proposed and there is significant clinical potential in priority areas such as vaccination. However, since their inception scientists have hypothesized about the risk of a clinically significant MAP-induced infection. Safety data from two major Phase 3 clinical trials involving hundreds of participants, who in total received tens of thousands of MAP applications, does not identify any clinically significant infections. However, the incumbent data set is not extensive enough to make definitive generalizable conclusions. A comprehensive assessment of the infection risk is therefore advised for MAP products, and this should be informed by clinical and pre-clinical data, theoretical analysis and informed opinions. In this article, a group of key stakeholders identify some of the key product- and patient-specific factors that may contribute to the risk of infection from a MAP product and provide expert opinions in the context of guidance from regulatory authorities. Considerations that are particularly pertinent to the MAP dosage form include the specifications of the finished product (e.g. microbial specification), it's design features, the setting for administration, the skill of the administrator, the anatomical application site, the target population and the clinical context. These factors, and others discussed in this article, provide a platform for the development of MAP risk assessments and a stimulus for early and open dialogue between developers, regulatory authorities and other key stakeholders, to expedite and promote development of safe and effective MAP products.

Production and characterization of long-acting recombinant human albumin-EPO fusion protein expressed in CHO cell.

A long-lasting recombinant human albumin-linker-erythropoietin (EPO) is a human albumin gene fused to the N-terminal of EPO with a (GGSGG)(n)-repeated linker inserted between albumin and EPO. Albumin-EPO fusion genes were co-transfected with the dhfr gene. Albumin-EPO fusion protein has three kinds of sub-types (IALE, AD2LE, AD1LE). Albumin-EPO fusion protein was quantified with human EPO ELISA. The in vitro efficacy of albumin-EPO fusion protein was estimated using F-36E cell, and in vivo efficacy of albumin-EPO fusion protein was estimated using normocythemic mice (B6D2F1). We also determined the in vivo half-life in a Sprague-Dawley rat. A PLA program analysis result demonstrated that the albumin-EPO fusion protein IALE is about 7.8-fold more potent than rHuEPO in increasing the hematocrit of normal mice.

Characterization of human cytotoxic T lymphocyte-associated antigen 4-immunoglobulin (hCTLA4Ig) expressed in transgenic rice cell suspension cultures.

The avidity for CD80Ig/CD86Ig and the in vitro immunosuppressive effect of recombinant human cytotoxic T lymphocyte-associated antigen 4-immunoglobulin, produced by transgenic rice cell suspension cultures (hCTLA4Ig(P)) with CHO-derived recombinant hCTLA4Ig (hCTLA4Ig(M)), were measured. Surface plasmon resonance (SPR) was used for kinetic binding analysis: hCTLA4Ig(P) and hCTLA4Ig(M) had higher avidity for CD80Ig/CD86Ig than for CD28Ig, and the avidity for CD80Ig/CD86Ig was similar. hCTLA4Ig(P) and hCTLA4Ig(M) had similar in vitro immunosuppressive activity against the expression of T cell-derived cytokines, such as IL-2, IL-4, and IFN-gamma, but did not suppress the expression of macrophage-derived cytokines, including TNF-alpha and IL-1beta, as well as NO. Thus the immunosuppressive mechanism of hCTLA4Ig(P) is also T cell-specific and it could therefore be used as an immunosuppressive agent with an equivalent potency to that of hCTLA4Ig(M).