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Volume 28, Number 11—November 2022
Research Letter

SARS-CoV-2 Omicron BA.1 Challenge after Ancestral or Delta Infection in Mice

Mariana Baz, Nikita Deshpande, Charlie Mackenzie-Kludas, Francesca Mordant, Danielle Anderson, and Kanta SubbaraoComments to Author 
Author affiliations: World Health Organization Collaborating Centre for Reference and Research on Influenza, Melbourne, Victoria, Australia (M. Baz, N. Deshpande, K. Subbarao); University of Melbourne Peter Doherty Institute for Infection and Immunity, Melbourne (C. Mackenzie-Kludas, F. Mordant, D. Anderson, K. Subbarao); Victorian Infectious Diseases Reference Laboratory, Melbourne (D. Anderson)

Main Article


Homologous and heterologous serum neutralizing antibody titers on days 27 and 56 after primary and secondary SARS-CoV-2 infection in hACE2K18 transgenic mice*

Primary infection, 102 TCID50 Secondary infection, 104 TCID50 Serum neutralizing antibodies (GMT) against indicated virus after primary and secondary infection
BA.1 BA.2† BA.5† Ancestral Delta
BA.1 BA.1 83/62 10/10 10/10 7‡/7‡ 7‡/8‡
Ancestral BA.1 34‡/27‡ 10/10 10/10 709/1,338 90‡/>440‡
Delta BA.1 16/60 10/35 10/53 55‡/124‡ 129/>453

*Bold indicates homologous titers. GMT, geometric mean titer; TCID50, 50% tissue culture infectious dose. †Lower limit of detection in indicated assays is 10. In other assays, the lower limit of detection is 5. ‡Serum samples from different sets of 5 mice from the group were tested on days 27 and 56.

Main Article

Page created: September 09, 2022
Page updated: October 24, 2022
Page reviewed: October 24, 2022
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