A visiting Japanese scientist working at the National Cancer Institute has admitted that he rigged part of a vaccine research project and fabricated data, his coauthors say in a printed retraction of a report on the project.

The coauthors say they were unaware that the lead author, Tatsumi Arichi, had rigged the experiment by 'spiking' a cell fluid with quantities of a virus to make it seem that the virus had grown in the cells. His coauthors called it a 'serious problem.'

The original paper describing the vaccine work appeared in the Jan. 4 2000 issue of the Proceedings of the National Academy of Sciences. That paper said that a DNA vaccine being tested in mice in the experiment was a 'potential candidate for a vaccine to prevent Hepatitis C,' which affects about 4 million Americans.

In the wake of that paper, scientists tried repeatedly to duplicate the results but were unable to do so.

The retraction appeared this week on the journal's website and will be published in the May 8 edition of the publication. Such retractions are occurring more frequently, said an official of the American Association for the Advancement of Science.

Boston Globe: 5/3/2001; page 4.