Changes in B Cell Responses to Coronaviruses in Kids, Adults

Memory B cells that bind to SARS-CoV-2 and cross-react with other coronaviruses were identified in kids even before the COVID-19 pandemic, as per the new study.

"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.

‘Early childhood B cell clonal expansions are vital for cross-reactivity of future responses to novel pathogens.’
Read More..

Tweet it Now

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.

Coronavirus
Coronaviruses infect animals, humans, and birds. Human coronaviruses, such as SARS, MERS, and 2019-nCoV cause respiratory distress and even death. The S protein is the infectious agent of the virus.

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.

Source-Eurekalert