The human immune response must continuously adapt to newly emerging SARS-CoV-2 variants. To investigate how B cells respond to repeated SARS-CoV-2 antigen exposure by Wu01 booster vaccination and Omicron breakthrough infection, we performed a molecular longitudinal analysis of the memory B cell pool. We demonstrate that a subsequent breakthrough infection substantially increases the frequency of B cells encoding SARS-CoV-2–neutralizing antibodies. However, this is not primarily attributable to maturation, but to selection of preexisting B cell clones. Moreover, broadly reactive memory B cells arose early and even neutralized highly mutated variants like XBB.1.5 that the individuals had not encountered. Together, our data show that SARS-CoV-2 immunity is largely imprinted on Wu01 over the course of multiple antigen contacts but can respond to new variants through preexisting diversity.

Three types of In₂O₃ nanoparticles decorated with Au, Pd and Pt nanoparticles, respectively, were synthesized by thermal decomposition method, and the effects of metal nanoparticles on their phase, microstructure, chemical state, carrier types were investigated with XRD, SEM/TEM, and XPS. Additionally, sensing properties to CO gas, such as sensitivity, etc., were examined with sensing apparatus. Au-decorated In₂O₃ nanoparticles exhibited the highest sensitivity to CO gas, with S = 5.59 at a 10 ppm CO gas concentration at 50 °C compared to Pd or Pt-decorated In₂O₃ nanoparticles. This can be interpreted as a much higher adsorption of oxygen molecules on the In₂O₃ surface due to the high oxygen vacancies in the In₂O₃ lattice, which generates an electron depletion region in the outer layer of In₂O₃ to sharply increase the resistance or the spill-over effect due to Au nanoparticles on In₂O₃. Au nanoparticles were observed in the TEM images and confirmed by XPS analysis.

Human immunodeficiency virus type 1 (HIV-1)-neutralizing antibodies (nAbs) that prevent infection are the main goal of HIV vaccine discovery. But as no nAb-eliciting vaccines are yet available, only data from HIV-1 neutralizers—persons with HIV-1 who naturally develop broad and potent nAbs—can inform about the dynamics and durability of nAb responses in humans, knowledge which is crucial for the design of future HIV-1 vaccine regimens. To address this, we assessed HIV-1-neutralizing immunoglobulin G (IgG) from 2,354 persons with HIV-1 on or off antiretroviral therapy (ART). Infection with non-clade B viruses, CD4⁺ T cell counts <200 µl⁻¹, being off ART and a longer time off ART were independent predictors of a more potent and broad neutralization. In longitudinal analyses, we found nAb half-lives of 9.3 and 16.9 years in individuals with no- or low-level viremia, respectively, and 4.0 years in persons who newly initiated ART. Finally, in a potent HIV-1 neutralizer, we identified lower fractions of serum nAbs and of nAb-encoding memory B cells after ART initiation, suggesting that a decreasing neutralizing serum activity after antigen withdrawal is due to lower levels of nAbs. These results collectively show that HIV-1-neutralizing responses can persist for several years, even at low antigen levels, suggesting that an HIV-1 vaccine may elicit a durable nAb response.