A one dose experimental cholera vaccine


Correspondence: William F. Wade, Department of Microbiology and Immunology, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA. Tel.: +1 603 650 6896; fax: +1 603 650 6223; e-mail: william.f.wade@dartmouth.edu


The number of cholera vaccine doses required for immunity is a constraint during epidemic cholera. Protective immunity following one dose of multiple Vibrio cholerae (Vc) colonization factors (Inaba LPS El Tor, TcpA, TcpF, and CBP-A) has not been directly tested even though individual Vc colonization factors are the protective antigens. Inaba LPS consistently induced vibriocidal and protective antibodies at low doses. A LPS booster, regardless of dose, induced highly protective secondary sera. Vc protein immunogens emulsified in adjuvant were variably immunogenic. CBP-A was proficient at inducing high IgG serum titers compared with TcpA or TcpF. After one immunization, TcpA or TcpF antisera protected only when the toxin co-regulated pilus operon of the challenge Vc was induced by AKI culture conditions. CBP-A was not consistently able to induce protection independent of the challenge Vc culture conditions. These results reveal the need to understand how best to leverage the ‘right’ Vc immunogens to obtain durable immunity after one dose of a cholera subunit vaccine. The dominance of the protective anti-LPS antibody response over other Vc antigen antibody response needs to be controlled to find other protective antigens that can add to anti-LPS antibody-based immunity.