Per os infectivity factors PIF1 (Ac119) and PIF2 (Ac022), like P74, are essential for oral infection of lepidopteran larval hosts of Autographa californica M nucleopolyhedrovirus (AcMNPV). Here we show that Ac115 also is a PIF (PIF3) and that, unlike PIF1 and PIF2, it does not mediate specific binding of AcMNPV occlusion-derived virus (ODV) to midgut target cells. We used an improved in vivo fluorescence dequenching assay to compare binding, fusion, and competition among control AcMNPV ODV and the ODVs of AcMNPV PIF1, PIF2, and PIF3 deletion mutants. Our results showed that binding and fusion of PIF1 and PIF2 mutants, but not the PIF3 mutant, were both qualitatively and quantitatively different from those of control ODV. Unlike control and PIF3-deficient ODV, an excess of PIF1-or PIF2-deficient ODV failed to compete effectively with control ODV's binding to specific receptors on midgut epithelial cells. Moreover, the levels of PIF1-and PIF2-deficient ODV binding were depressed threefold compared to control levels. Binding, fusion, and competition by PIF3-deficient ODV, however, were all indistinguishable from those of control ODV. These results implicated PIF1 and PIF2 as ODV envelope attachment proteins that mediate specific binding to primary target cells within the midgut. In contrast, PIF3 mediates another unidentified, but critical, early event during primary infection.

Purpose The unequal representation of women and people of color compared with men and whites in medical school textbooks has been well documented, as have health care inequities, and biases—both overt and implicit—by health care providers and in access to care. The authors investigated whether this bias exists in PowerPoint slides used in didactic material for preclinical students at one medical school. Method The authors analyzed 747 “decks” of slides from 33 preclinical courses in the medical school curriculum at the University of Washington School of Medicine in the years spanning 2009 to 2011. The authors coded the human images into various sex- and race-specific classifications and evaluated the distribution of images into these categories. Results Of the 4,033 images that could be coded by sex, 39.6% (1,595) were female and 60.5% (2,438) were male. Of the 5,230 images that could be coded by race/ethnicity, 78.4% (4,100) were white and 21.6% (1,130) were persons of color. Thus, images of whites and males predominated. Conclusions The proportion of images used in didactic courses at one school of medicine is not representative of the U.S. population in terms of race or sex. The authors discuss the potential sources and impact of this bias, make a case for sex and race diversity in didactic imagery, and propose possible avenues for further research and curricular reform in an era when the population is becoming increasingly racially and ethnically diverse.