  We report the discovery of a giant planet in the OGLE-2017-BLG-1522
microlensing event. The planetary perturbations were clearly identified by
high-cadence survey experiments despite the relatively short event timescale of
$t_{\rm E} \sim 7.5$ days. The Einstein radius is unusually small, $\theta_{\rm
E} = 0.065\,$mas, implying that the lens system either has very low mass or
lies much closer to the microlensed source than the Sun, or both. A Bayesian
analysis yields component masses $(M_{\rm host}, M_{\rm
planet})=(46_{-25}^{+79}, 0.75_{-0.40}^{+1.26})~M_{\rm J}$ and source-lens
distance $D_{\rm LS} = 0.99_{-0.54}^{+0.91}~{\rm kpc}$, implying that this is a
brown-dwarf/Jupiter system that probably lies in the Galactic bulge, a location
that is also consistent with the relatively low lens-source relative proper
motion $\mu = 3.2 \pm 0.5~{\rm mas}~{\rm yr^{-1}}$. The projected
companion-host separation is $0.59_{-0.11}^{+0.12}~{\rm AU}$, indicating that
the planet is placed beyond the snow line of the host, i.e., $a_{sl} \sim
0.12~{\rm AU}$. Planet formation scenarios combined with the small
companion-host mass ratio $q \sim 0.016$ and separation suggest that the
companion could be the first discovery of a giant planet that formed in a
protoplanetary disk around a brown dwarf host.
