Molecular Characterization of Heterologous HIV-1gp120 Gene Expression Disruption in Mycobacterium bovis BCG Host Strain: A Critical Issue for Engineering Mycobacterial Based-Vaccine Vectors

Mycobacterium bovis Bacillus Calmette-Guérin (BCG) as a live vector of recombinant bacterial vaccine is a promising system to be used. In this study, we evaluate the disrupted expression of heterologous HIV-1gp120 gene in BCG Pasteur host strain using replicative vectors pMV261 and pJH222. pJH222 carries a lysine complementing gene in BCG lysine auxotrophs. The HIV-1 gp120 gene expression was regulated by BCG hsp60 promoter (in plasmid pMV261) and Mycobacteria spp. α-antigen promoter (in plasmid pJH222). Among 14 rBCG:HIV-1gp120 (pMV261) colonies screened, 12 showed a partial deletion and two showed a complete deletion. However, deletion was not observed in all 10 rBCG:HIV-1gp120 (pJH222) colonies screened. In this study, we demonstrated that E. coli/Mycobacterial expression vectors bearing a weak promoter and lysine complementing gene in a recombinant lysine auxotroph of BCG could prevent genetic rearrangements and disruption of HIV 1gp120 gene expression, a key issue for engineering Mycobacterial based vaccine vectors

Newborn Mice Vaccination with BCG.HIVA222 + MVA.HIVA Enhances HIV-1-Specific Immune Responses: Influence of Age and Immunization Routes

We have evaluated the influence of age and immunization routes for induction of HIV-1- and M. tuberculosis-specific immune responses after neonatal (7 days old) and adult (7 weeks old) BALB/c mice immunization with BCG.HIVA222 prime and MVA.HIVA boost. The specific HIV-1 cellular immune responses were analyzed in spleen cells. The body weight of the newborn mice was weekly recorded. The frequencies of HIV-specific CD8+ T cells producing IFN-γ were higher in adult mice vaccinated intradermally and lower in adult and newborn mice vaccinated subcutaneously. In all cases the IFN-γ production was significantly higher when mice were primed with BCG.HIVA222 compared with BCGwt. When the HIV-specific CTL activity was assessed, the frequencies of specific killing were higher in newborn mice than in adults. The prime-boost vaccination regimen which includes BCG.HIVA222 and MVA.HIVA was safe when inoculated to newborn mice. The administration of BCG.HIVA222 to newborn mice is safe and immunogenic and increased the HIV-specific responses induced by MVA.HIVA vaccine. It might be a good model for infant HIV and Tuberculosis bivalent vaccine

Outcomes and clinical characteristics of the compassionate use of plitidepsin for immunocompromised adult patients with COVID-19

Objectives: To evaluate the compassionate use of plitidepsin as an antiviral treatment in hospitalized immunocompromised adult patients with moderate-to-severe COVID-19. Design: Retrospective observational study of data —collected from January 01, 2021 to April 30, 2022— from 35 immunocompromised adult patients with COVID-19 non-eligible for other available antiviral treatments. Main outcome measures were time to respiratory recovery (SpFi ≥ 315); COVID-19-related 30-day-cumulative mortality after first plitidepsin infusion; and time to undetectable levels of viral RNA. Results: Thirty-three patients receiving a full course of plitidepsin (2.5 mg [n = 29] or 1.5 mg [n = 4]) were included. Most (69.7%) had a malignant hematologic disease and 27.3% had solid tumors. A total of 111 infusions were administered with lack of relevant safety events. Median time from plitidepsin initiation to SpFi ≥315 was 8 days (95% confidence interval [CI], 7-19). Median time to first negative reverse transcription-polymerase chain reaction for SARS-CoV-2 (cycle threshold >36) was 17 days (95% CI 13-25). Mortality rate was 16.3% (95% CI 3-37.3). Conclusion: These data support plitidepsin as a well-tolerated treatment that might have potential clinical and antiviral efficacy in COVID-19 immunocompromised patients