RESUMO
The global spread of the Omicron variant strain BA.5/BF.7 has led to an increase in breakthrough infections. The elderly population shows different immune responses after infection due to the aging of the immune system, which has not been fully studied. The aim of this study was to investigate the effect of aging on immune response after breakthrough infection of Omicron BA.5/BF.7 variant, especially the changes of protein immune mechanism. The study analyzed the concentration of antibodies in serum and their ability to neutralize the mutant strain by comparing the immune response of the elderly population and the young population after infection. Proteomics techniques were used to assess differences in the expression of key proteins in immune cells of different age groups. The study found that older subjects produced lower levels of antibodies after infection than younger subjects and showed a significantly reduced ability to neutralize against BA.5/BF.7. In addition, proteomic analysis showed that the expression of proteins related to inflammation and apoptosis significantly increased in the immune cells of the elderly, while the proteins related to antiviral response and cell repair significantly decreased. These findings provide new ideas for immune intervention strategies in the elderly population, and emphasize the targeted research of anti-virus vaccines.
RESUMO
From December 2022 to January 2023, SARS-CoV-2 infections caused by BA.5 and BF.7 subvariants of B.1.1.529 (Omicron) spread in China. It is urgently needed to evaluate the protective immune responses in the infected individuals against the current circulating variants to predict the future potential infection waves, such as the BQ.1.1, XBB.1.5, and CH1.1 variants. In this study, we constructed a panel of pseudotyped viruses for SARS-CoV-2 for the past and current circulating variants, including D614G, Delta, BA.1, BA.5, BF.7, BQ.1.1, XBB.1.5 and CH.1.1. We investigated the neutralization sensitivity of these pseudotyped viruses to sera from individuals who had BA.5 or BF.7 breakthrough infections in the infection wave of last December in China. The mean neutralization ID50 against infected variants BA.5 and BF.7 are 533 and 444, respectively. The highest neutralizing antibody level was observed when tested against the D614G strain, with the ID50 of 742, which is about 1.52-folds higher than that against the BA.5/BF.7 variant. The ID50 for BA.1, Delta, and BQ.1.1 pseudotyped viruses were about 2-3 folds lower when compared to BA.5/BF.7. The neutralization activities of these serum samples against XBB.1.5 and CH.1.1 decreased 7.39-folds and 15.25-folds when compared to that against BA.5/BF.7. The immune escape capacity of these two variants might predict new infection waves in future when the neutralizing antibody levels decrease furtherly.