Effects of purine nucleosides on the in vitro growth of Cryptosporidium parvum

International audienceThe effect of purine nucleosides on the in vitro growth of Cryptosporidium parvum was studied. Culturing the parasite in THP-1 cells for 72 h in growth medium supplemented with adenosine or inosine improved the parasite yields especially in the first 48 h. Similar results were obtained with parasites cultured in Madin^Darby bovine kidney cells and incubated for 24 h with inosine. The addition of inosine to 72-h cultures enhanced the growth of C. parvum in THP-1 cells, especially the trophic stages, whereas the analogue formycin B was toxic to the parasites and induced a marked decrease in the gamont stages. The monitoring of the added purine nucleosides by high performance liquid chromatography showed that at 37 ‡C in the presence of THP-1 cells, a rapid uptake of inosine occurred with hypoxanthine being the main purine present after 2 h in the medium

Use of a non-adherent cell culture system for testing the effect of 2',3'-dideoxyinosine against Cryptosporidium parvum

International audienceThe in vitro cultivation of Cryptosporidium parvum in the non-adherent cell line THP-1 was evaluated for its capability as a useful additional model to investigate the effect of drugs on this parasite. The purine analog antiviral 2',3'-dideoxyinosine (ddI) was evaluated and compared to the reference molecule paromomycin in sequential 24 hour experiments beginning at 24 and 72 hour post-infection. The ability of this technique to evaluate the various parasite stages showed that ddI displayed a dose-dependent efficacy especially on the trophozoite and sexual stages. Paromomycin displayed a lower efficacy than previously reported. Both drugs induced a decrease in the number of multiparasitized cells. These results indicate that the purine salvage pathway should be a key chemotherapeutic target against C. parvum

Validation d'une méthode de dosage du cuivre dans le sérum par spectrométrie d'absorption atomique électrothermique

Objectif : Un déséquilibre du métabolisme du cuivre est à l'origine de maladies génétiques graves ; la maladie de Menkès lors de déficits en cuivre et la maladie de Wilson caractérisée par une surcharge en cet oligo-élément. Le diagnostic des ces pathologies implique le dosage du cuivre sérique et urinaire par spectrométrie d'absorption atomique électrothermique (SAAE). Nous décrivons ici le protocole de validation de notre technique de dosage du cuivre sérique par SAA. Méthode : Nous avons appliqué un protocole recommandé par la Société Française des Sciences Techniques et Pharmaceutiques (SFSTP). Résultats : Ce protocole nous a permis de tester la linéarité, la fidélité et l'exactitude de notre méthode et de définir le domaine de linéarité ainsi que les limites de détection et de quantification. Conclusion : L'étude réalisée a permis de valider la méthode de dosage utilisée au laboratoire

Long-term systemic and mucosal SARS-CoV-2 IgA response and its association with persistent smell and taste disorders

International audienceIntroduction: Current approved COVID-19 vaccines, notably mRNA and adenoviral vectored technologies, still fail to fully protect against infection and transmission of various SARS-CoV-2 variants. The mucosal immunity at the upper respiratory tract represents the first line of defense against respiratory viruses such as SARS-CoV-2 and is thus critical to develop vaccine blocking human-to-human transmission.Methods: We measured systemic and mucosal Immunoglobulin A (IgA) response in serum and saliva from 133 healthcare workers from Percy teaching military hospital following a mild infection (SARS-CoV-2 Wuhan strain, n=58) or not infected (n=75), and after SARS-CoV-2 vaccination (Vaxzevria®/Astrazeneca and/or Comirnaty®/Pfizer).Results: While serum anti-SARS-CoV-2 Spike IgA response lasted up to 16 months post-infection, IgA response in saliva had mostly fallen to baseline level at 6 months post-infection. Vaccination could reactivate the mucosal response generated by prior infection, but failed to induce a significant mucosal IgA response by itself. Early post-COVID-19 serum anti-Spike-NTD IgA titer correlated with seroneutralization titers. Interestingly, its saliva counterpart positively correlated with persistent smell and taste disorders more than one year after mild COVID-19.Discussion: As breakthrough infections have been correlated with IgA levels, other vaccine platforms inducing a better mucosal immunity are needed to control COVID-19 infection in the future. Our results encourage further studies to explore the prognosis potential of anti-Spike-NTD IgA in saliva at predicting persistent smell and taste disorders