Post by Nadica (She/Her) on Aug 2, 2024 2:25:58 GMT
Antigenic cartography using variant-specific hamster sera reveals substantial antigenic variation among Omicron subvariants - Published July 30, 2024
Significance
Since late 2020, severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) variants capable of evading the immune response from previous infection or vaccination have emerged. Understanding and tracking changes in antigenicity is a crucial component of vaccine design and update. Finding human first-infection sera to measure antigenic distances between novel variants is becoming impossible, as most people have been infected or vaccinated. Therefore, an alternative (nonhuman) model is needed. We evaluated hamster sera as a surrogate to human first-infection sera to measure antigenic differences between recently circulating variants. We find a closer antigenic relationship between the pre-Omicron variants circulating in 2020 and 2021 and larger distances between Omicron variants.
Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) has developed substantial antigenic variability. As the majority of the population now has pre-existing immunity due to infection or vaccination, the use of experimentally generated animal immune sera can be valuable for measuring antigenic differences between virus variants. Here, we immunized Syrian hamsters by two successive infections with one of nine SARS-CoV-2 variants. Their sera were titrated against 16 SARS-CoV-2 variants, and the resulting titers were visualized using antigenic cartography. The antigenic map shows a condensed cluster containing all pre-Omicron variants (D614G, Alpha, Delta, Beta, Mu, and an engineered B.1+E484K variant) and considerably more diversity among a selected panel of Omicron subvariants (BA.1, BA.2, BA.4/BA.5, the BA.5 descendants BF.7 and BQ.1.18, the BA.2.75 descendant BN.1.3.1, the BA.2-derived recombinants XBB.2 and EG.5.1, and the BA.2.86 descendant JN.1). Some Omicron subvariants were as antigenically distinct from each other as the wildtype is from the Omicron BA.1 variant. Compared to titers measured in human sera, titers in hamster sera are of higher magnitude, show less fold change, and result in a more compact antigenic map topology. The results highlight the potential of sera from hamsters for the continued antigenic characterization of SARS-CoV-2.
Significance
Since late 2020, severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) variants capable of evading the immune response from previous infection or vaccination have emerged. Understanding and tracking changes in antigenicity is a crucial component of vaccine design and update. Finding human first-infection sera to measure antigenic distances between novel variants is becoming impossible, as most people have been infected or vaccinated. Therefore, an alternative (nonhuman) model is needed. We evaluated hamster sera as a surrogate to human first-infection sera to measure antigenic differences between recently circulating variants. We find a closer antigenic relationship between the pre-Omicron variants circulating in 2020 and 2021 and larger distances between Omicron variants.
Severe acute respiratory syndrome Coronavirus 2 (SARS-CoV-2) has developed substantial antigenic variability. As the majority of the population now has pre-existing immunity due to infection or vaccination, the use of experimentally generated animal immune sera can be valuable for measuring antigenic differences between virus variants. Here, we immunized Syrian hamsters by two successive infections with one of nine SARS-CoV-2 variants. Their sera were titrated against 16 SARS-CoV-2 variants, and the resulting titers were visualized using antigenic cartography. The antigenic map shows a condensed cluster containing all pre-Omicron variants (D614G, Alpha, Delta, Beta, Mu, and an engineered B.1+E484K variant) and considerably more diversity among a selected panel of Omicron subvariants (BA.1, BA.2, BA.4/BA.5, the BA.5 descendants BF.7 and BQ.1.18, the BA.2.75 descendant BN.1.3.1, the BA.2-derived recombinants XBB.2 and EG.5.1, and the BA.2.86 descendant JN.1). Some Omicron subvariants were as antigenically distinct from each other as the wildtype is from the Omicron BA.1 variant. Compared to titers measured in human sera, titers in hamster sera are of higher magnitude, show less fold change, and result in a more compact antigenic map topology. The results highlight the potential of sera from hamsters for the continued antigenic characterization of SARS-CoV-2.