Immune responses to intracellular pathogens depend largely upon the activation of T helper type 1-dependent mechanisms. The contribution of B cells to establishing protective immunity has long been underestimated. Francisella tularensis, including a number of subspecies, provides a suitable model for the study of immune responses against intracellular bacterial pathogens. We previously demonstrated that Francisella infects B cells and activates B-cell subtypes to produce a number of cytokines and express the activation markers. Recently, we documented the early production of natural antibodies as a consequence of Francisella infection in mice. Here, we summarize current knowledge on the innate and acquired humoral immune responses initiated by Francisella infection and their relationships with the immune defense systems.

• Keywords
• B cells, Francisella tularensis, intracellular pathogen, natural antibodies, natural immunity,
• Publication type
• Journal Article MeSH
• Review MeSH

SARS-CoV-2 infection induces the production of autoantibodies, which is significantly associated with complications during hospitalization and a more severe prognosis in COVID-19 patients. Such a response of the patient's immune system may reflect (1) the dysregulation of the immune response or (2) it may be an attempt to regulate itself in situations where the non-infectious self poses a greater threat than the infectious non-self. Of significance may be the primary virus-host cell interaction where the surface-bound ACE2 ectoenzyme plays a critical role. Here, we present a brief analysis of recent findings concerning the immune recognition of SARS-CoV-2, which, we believe, favors the second possibility as the underlying reason for the production of autoantibodies during COVID-19.

• Keywords
• ACE2 signaling, COVID-19, SARS-CoV-2, autoantibodies, innate immune recognition,
• Publication type
• Journal Article MeSH