Complementarity determining regions in SARS-CoV-2 hybrid immunity.

Pre-vaccination SARS-CoV-2 infection can boost protection elicited by COVID-19 vaccination and post-vaccination breakthrough SARS-CoV-2 infection can boost existing immunity conferred by COVID-19 vaccination. Such 'hybrid immunity' is effective against SARS-CoV-2 variants. In order to understand 'hybrid immunity' at the molecular level we studied the complementarity determining regions (CDR) of anti-RBD (receptor binding domain) antibodies isolated from individuals with 'hybrid immunity' as well as from 'naive' (not SARS-CoV-2 infected) vaccinated individuals. CDR analysis was done by liquid chromatography/mass spectrometry-mass spectrometry. Principal component analysis and partial least square differential analysis showed that COVID-19 vaccinated people share CDR profiles and that pre-vaccination SARS-CoV-2 infection or breakthrough infection further shape the CDR profile, with a CDR profile in hybrid immunity that clustered away from the CDR profile in vaccinated people without infection. Thus, our results show a CDR profile in hybrid immunity that is distinct from the vaccination-induced CDR profile.

Contact allergy mimicking trench foot infection: a case study.

Hard-to-heal wounds are a major cause of morbidity and/or mortality. Multiple aetiologies can be identified and wounds can be treated according to their aetiology and macroscopic appearance. However, evidence behind the wide range of locally applied treatments is weak, without clear guidelines available to treat a variety of wound aetiologies. We present the case of a 63-year-old male with hard-to-heal wounds not responding to standard topical treatment. No clear underlying aetiology could be found. Extensive contact allergies were diagnosed after multiple topical and systemic treatments had been applied. A full recovery was observed after stopping topical agents and treating the wounds with an alternative treatment based on epicutaneous test results.