Differences in B Cell Responses to Coronaviruses And Other Pathogens in Children And Adults (Medicine)

Blood taken from a small group of children before the COVID-19 pandemic contains memory B cells that bind SARS-CoV-2 and weakly cross-react with other coronaviruses, a new study finds, while adult blood and tissue showed few such cells.

“Further study of the role of cross-reactive memory B cell populations… will be important for ongoing improvement of vaccines to SARS-CoV-2, its viral variants, and other pathogens,” the authors say.

As the COVID-19 pandemic has continued, children have often exhibited faster viral clearance and lower viral antigen loads than adults; whether B cell repertoires against SARS-CoV-2 (and other pathogens) differ between children and adults, contributing to differential responses, remains unknown. More broadly, it is still unclear how B cell memory to different antigens distributes in human tissues and changes during an individual’s lifespan.

To study this, Fan Yang et al. analyzed blood samples taken from pre-pandemic children and pre-pandemic adults. They also studied blood and tissue samples from deceased organ donors. The authors analyzed B cell receptor (BCR) repertoires – which reveal the antigen a B cell targets – specific to six common pathogens as well as two viruses the participants had not encountered before: Ebola virus and SARS-CoV-2.

In comparison to adults, pre-pandemic children not only had higher frequencies of convergent (shared) B cell clones in their blood for pathogens they have encountered, but also higher frequencies of class-switched convergent B cell clones against SARS-CoV-2 and its viral variants. Adult blood and tissues showed few such clones.

Notably, neither children nor adults had many BCRs for Ebola virus, highlighting the contrast to SARS-CoV-2 and other human coronaviruses commonly encountered prior to the current pandemic.

“We hypothesize that previous [coronavirus] exposures may stimulate cross-reactive memory, and that such clonal responses may have their highest frequencies in childhood,” the authors say.

The results highlight the prominence of early childhood B cell clonal expansions and cross-reactivity for future responses to novel pathogens.

Reference: Fan Yang, Sandra C. A. Nielsen, Ramona A. Hoh, Katharina Röltgen, Oliver Fabian Wirz, Emily Haraguchi, Grace H. Jean, Ji-Yeun Lee, Tho D. Pham, Katherine J. L. Jackson, Krishna M. Roskin, Yi Liu, Khoa Nguyen, Robert S. Ohgami, Eleanor M. Osborne, Kari C. Nadeau, Claus U. Niemann, Julie Parsonnet, Scott D. Boyd, “Shared B cell memory to coronaviruses and other pathogens varies in human age groups and tissues”, Science  12 Apr 2021: eabf6648 DOI: 10.1126/science.abf6648

Provided by AAAS

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