Formation and Expansion of Memory B Cells against Coronavirus in Acutely Infected COVID-19 Individuals.

Infection with the β-coronavirus SARS-CoV-2 typically generates strong virus-specific antibody production. Antibody responses against novel features of SARS-CoV-2 proteins require naïve B cell activation, but there is a growing appreciation that conserved regions are recognized by pre-existing memory B cells (MBCs) generated by endemic coronaviruses. The current study investigated the role of pre-existing cross-reactive coronavirus memory in the antibody response to the viral spike (S) and nucleocapsid (N) proteins following SARS-CoV-2 infection.

CD4+ T-cell expansion predicts neutralizing antibody responses to monovalent, inactivated 2009 pandemic influenza A(H1N1) virus subtype H1N1 vaccine.

Background: The ability of influenza vaccines to elicit CD4(+) T cells and the relationship between induction of CD4(+) T cells and vaccine-induced neutralizing antibody responses has been controversial. The emergence of swine-origin 2009 pandemic influenza A virus subtype H1N1 (A[H1N1]pdm09) provided a unique opportunity to examine responses to an influenza vaccine composed of both novel and previously encountered antigens and to probe the relationship between B-cell and T-cell responses to vaccination.

Methods: We tracked CD4(+) T-cell and antibody responses of human subjects vaccinated with monovalent subunit A(H1N1)pdm09 vaccine.