Immunity following SARS-CoV-2 vaccination in autoimmune neurological disorders treated with rituximab or ocrelizumab.

Background: Rituximab (RTX) and ocrelizumab (OCR), B cell-depleting therapy targeting CD20 molecules, affect the humoral immune response after vaccination. How these therapies influence T-cell-mediated immune response against SARS-CoV-2 after immunization remains unclear. We aimed to evaluate the humoral and cellular immune response to the COVID-19 vaccine in a cohort of patients with multiple sclerosis (MS), neuromyelitis optica spectrum disorders (NMOSD), and myasthenia gravis (MG). Methods: Patients with MS (83), NMOSD (19), or MG (7) undergoing RTX (n=47) or OCR (n=62) treatment were vaccinated twice with the mRNA BNT162b2 vaccine. Antibodies were quantified using the SARS-CoV-2 IgG chemiluminescence immunoassay, targeting the spike protein. SARS-CoV-2-specific T cell responses were quantified by interferon γ release assays (IGRA). The responses were evaluated at two different time points (4-8 weeks and 16-20 weeks following the 2nd dose of the vaccine). Immunocompetent vaccinated individuals (n=41) were included as controls. Results: Almost all immunocompetent controls developed antibodies against the SARS-CoV-2 trimeric spike protein, but only 34.09% of the patients, without a COVID-19 history and undergoing anti-CD20 treatment (via RTX or OCR), seroconverted. This antibody response was higher in patients with intervals of longer than 3 weeks between vaccinations. The duration of therapy was significantly shorter in seroconverted patients (median 24 months), than in the non-seroconverted group. There was no correlation between circulating B cells and the levels of antibodies. Even patients with a low proportion of circulating CD19+ B cells (<1%, 71 patients) had detectable SARS-CoV-2 specific antibody responses. SARS-CoV-2 specific T cell response measured by released interferon γ was detected in 94.39% of the patients, independently of a humoral immune response. Conclusion: The majority of MS, MG, and NMOSD patients developed a SARS-CoV-2-specific T cell response. The data suggest that vaccination can induce SARS-CoV-2-specific antibodies in a portion of anti-CD20 treated patients. The seroconversion rate was higher in OCR-treated patients compared to those on RTX. The response represented by levels of antibodies was better in individuals, with intervals of longer than 3 weeks between vaccinations.

[Detection of Francisella tularensis by blood culture]. / Záchyt Francisella tularensis pomocí hemokultivace.

Francisella tularensis, from the family Francisellaceae, is the aetiological agent of a zoonosis called tularaemia, spread throughout the northern hemisphere. The infectious dose is extremely low (10 CFU/ml) and the infection causes severe diseases or even death if untreated. The transmission to humans is always related to animals, either by a direct contact or by a contact with the environment contaminated by them. Clinical symptoms of the disease can vary depending on the point of entry of the infection. Tularaemia may also occur without any local symptoms or can be manifested by a combination of the symptoms of various typical clinical forms. F. tularensis is a fastidious bacterium and it is rarely diagnosed by blood culture.

[Tularaemia - an overview of the current knowledge]. / Tulerémie- prehled soucasných poznatku

Francisella tularensis belongs to the family Francisellaceae. It is the aetiological agent of a zoonosis called tularaemia, spread throughout the northern hemisphere. Currently, several subspecies of F. tularensis may be distinguished with various pathogenicity and geographical distribution. In human medicine, only sporadic infections or local epidemics are reported. Given the fact that F. tularensis is highly pathogenic for humans and is easily spread by aerosol, water or food, it may be exploited as a biological weapon. It belongs to fastidious strains requiring specially prepared culture media.