  We present new simulations investigating the impact of mass transfer on the
asteroseismic signals of slowly pulsating B stars. We use MESA to simulate the
evolution of a binary star system and GYRE to compute the asteroseismic
properties of the accretor star. We show that, compared to a single star of the
same final mass, a star that has undergone accretion (of non-enriched material)
has a significantly different internal structure, evident in both the hydrogen
abundance profile and Brunt-V\"ais\"al\"a frequency profile. These differences
result in significant changes in the observed period spacing patterns, implying
that one may use this as a diagnostic to test whether a star's core has been
rejuvenated as a result of accretion. We show that it is essential to consider
the full multimodal posterior distributions when fitting stellar properties of
mass-gainers to avoid drawing misleading conclusions. Even with these
considerations, stellar ages will be significantly underestimated when assuming
single star evolution for a mass-gainer. We find that future detectors with
improved uncertainties would rule out single star models with the correct mass
and central hydrogen fraction. Our proof of principle analysis demonstrates the
need to further investigate the impact of binary interactions on stellar
asteroseismic signals for a wide range of parameters, such as initial mass,
amount of mass transferred and the age of the accretor star at the onset of
mass transfer.
