Complementation of the MS-H vaccine strain with wild-type influences its growth characteristics.

The (MS) vaccine strain MS-H harbours a frameshift mutation in (oligopeptide permease transporter) which results in expression of a truncated OppF. The effect of this mutation on growth and attenuation of the MS-H is unknown. In this study, the impact of the mutation on the vaccine phenotype was investigated by introducing a wild-type copy of gene in the MS-H genome.