Figure 9. CD169 contributes to retrovirus particle acquisition and establishment of infection during oral challenge.

(A) Image of a Peyer’s patch (PP) cryosection from a 3-day-old neonatal B6 mouse. Macrophages in the developing follicle were identified using antibodies to surface marker CD169 (red), and dotted lines demarcate the epithelium from intestinal lumen. (B) Representative images of gastrointestinal tracts isolated from a neonatal B6 and CD169^-/- mice 48 hr after oral challenge with 1 × 10⁶ IU of murine leukemia virus (MLV) Env-Nluc at 3 days of age to show comparative accumulation of bioluminescent viruses in PP and mesenteric sac (mSac). Scale bars shown for bioluminescence imaging denote radiance in photons per second per square centimeter per steradian (p/s/cm²/sr). (C, D) Quantification of virus transit to PP (C) and mSacs (D) at 48 hr post infection (hpi) in B6 and CD169^-/- mice from the experiment described in (B). Virus transit was quantified as Nluc photon flux (photons/s). (E) FrMLV-infected cells 5 dpi (oral., 1 × 10⁶ IU) in mSac (n = 6–8) from neonatal B6 and CD169^−/− mice challenged at 3 days of age. Single-cell suspensions of cells from individual mSacs were obtained at 5 dpi and processed for flow cytometry. Infection levels were determined using antibodies to FrMLV GlycoGag. p values derived from non-parametric Mann–Whitney test; mean values denoted by horizontal line.