BiodefenseJapanese attenuated smallpox vaccine shows promise in U.S. trial
An attenuated smallpox vaccine that was developed in Japan in the 1970s compared well with a conventional smallpox vaccine in a phase 1-2 clinical trial in the United States
An attenuated smallpox vaccine that was developed in Japan in the 1970s compared well with a conventional smallpox vaccine in a phase 1-2 clinical trial in the United States, according to a report last week in the Journal of Infectious Diseases.
The Center for Infectious Disease Research and Policy (CIDRAP) says that the vaccine, called LC16m8, consists of vaccinia virus weakened by deletion of the B5R protein. It was tested extensively in Japan and has been used to vaccinate some military personnel there. In the double-blind U.S. trial, 154 young adult volunteers at five centers were randomly assigned to receive LC16m8 or the conventional vaccine, Dryvax, and were monitored for immune response and adverse events. Local and systemic reactions to the vaccines were similar in the two groups. In immunogenicity testing, serum samples from both groups generated neutralizing antibody titers greater than 1:40 against vaccinia (the vaccine virus), smallpox (variola), and monkeypox viruses. The attenuated vaccine also generated “robust cellular immune responses” that trended higher than the Dryvax responses by one measure but lower by another.
The authors concluded that the vaccine was well tolerated, that it “may have efficacy in protecting individuals from smallpox,” and that it warrants further development.
— Read more in Jeffrey S. Kennedy et al., “Safety and Immunogenicity of LC16m8, an Attenuated Smallpox Vaccine in Vaccinia-Naive Adults,” Journal of Infectious Diseases (15 September 2011) (doi: 10.1093/infdis/jir527)
