June 6th 2024

Published in Viruses: Lower infectivity of recent SARS-CoV-2 omicron sub–variants in Syrian Hamster

Published in Viruses: Lower infectivity of recent SARS-CoV-2 omicron sub–variants in Syrian Hamster.

The CARE partner, KU Leuven (KUL) evaluated the infectivity of two important sub-variants of omicron in Syrian hamsters. Indeed, since the emergence of the first omicron SARS-CoV-2 variant at the end of 2021, several sub-variants have evolved and become predominant in the human population, showing enhanced transmissibility and ability to (partly) escape the adaptive immune response. These include EG.5.1, an XBB sub-variant, and BA.2.86, a phylogenetically distinct variant, which were compared to the BA.5 sub-variant, a preceding BA.2 descendant. The BA.2 variant was not chosen as a comparator as it does not replicate efficiently in the KUL hamster model as compared to the BA.5 sub-variant.

Both EG.5.1 and BA.2.86 sub-variants are attenuated in Syrian hamsters as compared to the BA.5 sub-variant, as shown by lower infectious titers in the lung and lower lung pathology scores, while the viral RNA loads in throat swabs were comparable in the 3 strains. Interestingly, no virus titers in the lungs of the hamsters infected with the BA.2.86 sub-variant were observed although high viral RNA loads were detected. Therefore, viral RNA loads in the throat swabs and the lungs as well as lung histopathology scores could be a more suitable readout for vaccine and antiviral studies involving these two new sub-variants.

The continuous emergence of sub-variants will remain a challenge as it may require updating vaccines and therapeutic antibodies. Pre-clinical models with the evolving sub-variants are therefore crucial not only to study the virological characteristics of these new sub-variants, but more importantly to evaluate the efficacy of updated and also novel vaccines as well as therapeutic options for which the efficacy is virus variant dependent such as neutralizing antibodies.

To learn more, click here: Comparing the Infectivity of Recent SARS-CoV-2 Omicron Sub-Variants in Syrian Hamsters