  The Infrared Spectrograph (IRS) onboard the Spitzer Space Telescope (SST) has
been used to obtain low and moderate resolution spectra of the dust and
gas-rich quasar APM08279+5255 (z=3.91). Broad Paschen $\alpha$ and $\beta$
recombination lines of hydrogen were detected at wavelengths of 9.235 and
6.315microns, as well as a strong, red continuum that is a smooth power law
over the observed (rest frame) wavelength range 5.3-35microns (1.08 -
7.1microns). The observed P$\alpha$/P$\beta$ line flux ratio of 1.05$\pm$0.2 is
far from the case B value of ~2 and simple models of high density, high optical
depth ionized gas regions (~1.8). This deviation is opposite in sense to the
expected effect of reddening. No evidence is found in the spectrum for either
the 3.3micron or 6.2micron emission features usually attributed to aromatic
hydrocarbons in gas rich galaxies in the local Universe. This is consistent
with the high luminosity AGN nature of APM08279+5255.
