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We aimed to evaluate the association between the humoral and cellular immune responses and symptomatic SARS‐CoV‐2 infection with Delta or Omicron BA.1 variants in fully vaccinated outpatients. Anti‐receptor binding domain (RBD) IgG levels and interferon‐gamma (IFN‐γ) release were evaluated at PCR‐diagnosis of SARS‐CoV‐2 in 636 samples from negative and positive patients during Delta and Omicron BA.1 periods. Median levels of anti‐RBD IgG in positive patients were significantly lower than in negative patients for both variants (p < 0.05). The frequency of Omicron BA.1 infection in patients with anti‐RBD IgG concentrations ≥1000 binding antibody units (BAU)/mL was 51.0% and decreased to 34.4% in patients with concentrations ≥3000 BAU/mL. For Delta infection, the frequency of infection was significantly lower when applying the same anti‐RBD IgG thresholds (13.3% and 5.3% respectively, p < 0.05). In addition, individuals in the hybrid immunity group had a 4.5 times lower risk of Delta infection compared to the homologous vaccination group (aOR = 0.22, 95% CI: [0.05−0.64]. No significant decrease in the risk of Omicron BA.1 infection was observed in the hybrid group compared to the homologous group, but the risk decreased within the hybrid group as anti‐RBD IgG titers increased (aOR = 0.08, 95% CI: [0.01−0.41], p = 0.008). IFN‐γ release post‐SARS‐CoV‐2 peptide stimulation was not different between samples from patients infected (either with Delta or Omicron BA.1 variant) or not (p > 0.05). Our results show that high circulating levels of anti‐RBD IgG and hybrid immunity were independently associated with a lower risk of symptomatic SARS‐CoV‐2 infection in outpatients with differences according to the infecting variant (www.clinicaltrials.gov; ID NCT05060939). [ABSTRACT FROM AUTHOR]

The emergence and sustained transmission of novel pathogens are exerting an increasing demand on the diagnostics sector worldwide, as seen with the ongoing severe acute respiratory coronavirus 2 (SARS‐CoV‐2) pandemic and the more recent public health concern of monkeypox virus (MPXV) since May 2022. Appropriate and reliable viral inactivation measures are needed to ensure the safety of personnel handling these infectious samples. In the present study, seven commercialized diagnosis buffers, heat (56°C and 60°C), and sodium dodecyl sulfate detergent (2.0%, 1.0%, and 0.5% final concentrations) were tested against infectious SARS‐CoV‐2 and MPXV culture isolates on Vero cell culture. Cytopathic effects were observed up to 7 days postinoculation and viral load evolution was measured by semiquantitative polymerase chain reaction. The World Health Organization recommends an infectious titer reduction of at least 4 log10. As such, the data show efficacious SARS‐CoV‐2 inactivation by all investigated methods, with >6.0 log10 reduction. MPXV inactivation was also validated with all investigated methods with 6.9 log10 reductions, although some commercial buffers required a longer incubation period to yield complete inactivation. These results are valuable for facilities, notably those without biosafety level‐3 capabilities, that need to implement rapid and reliable protocols common against both SARS‐CoV‐2 and MPXV. [ABSTRACT FROM AUTHOR]

Background: In prepubertal boys with cancer, fertility preservation relies on testicular tissue freezing before treatment. In vitro maturation of frozen/thawed tissues could be one of the procedures envisaged to restore the fertility of cured patients. It is necessary to ascertain in the mouse model that in vitro‐generated spermatozoa are able to ensure embryo development, without altering the epigenetic processes occurring during the pre‐implantation period. Objectives: The aims of the present study were to investigate the fertilizing ability of in vitro‐produced spermatozoa and explore several epigenetic marks at different stages of embryo development. Materials and methods: Fresh or controlled slow‐frozen (CSF)/thawed testicular tissues from 6 to 7 days post‐partum (dpp) mice were cultured for 30 days. Intracytoplasmic sperm injection (ICSI) experiments were performed using in vitro‐produced spermatozoa. Testicular spermatozoa from 36 to 37 dpp mice were used as in vivo controls. DNA methylation/hydroxymethylation and histone post‐translational modifications (H3K4me3, H3K27me3 and H3K9ac) were analysed by immunofluorescence from the zygote to the blastocyst stages. Results: The spermatozoa generated in cultures of fresh or CSF testicular tissues were able to initiate embryonic development. The freezing of prepubertal testicular tissues limits the production of spermatozoa in vitro and the fertilization rate after ICSI. Similar levels of H3K4me3, H3K27me3 and H3K9ac were found in ICSI embryos derived from in vitro‐ and in vivo‐produced spermatozoa. DNA methylation levels were increased in 4‐cell embryos and morula obtained by ICSI with in vitro‐produced spermatozoa. Discussion and conclusion: Our study shows for the first time that the use of in vitro‐produced spermatozoa alters DNA methylation/demethylation dynamics but has little impact on H3K4me3, H3K27me3 and H3K9ac levels in mouse early embryos. Further work will have to be performed to determine whether the use of these gametes is not deleterious for embryo development before considering a human application. [ABSTRACT FROM AUTHOR]

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