Visualization of HIV-1 interactions with penile and foreskin epithelia: clues for female-to-male HIV transmission.
To gain insight into female-to-male HIV sexual transmission and how male circumcision protects against this mode of transmission, we visualized HIV-1 interactions with foreskin and penile tissues in ex vivo tissue culture and in vivo rhesus macaque models utilizing epifluorescent microscopy. 12 foreskin and 14 cadaveric penile specimens were cultured with R5-tropic photoactivatable (PA)-GFP HIV-1 for 4 or 24 hours. Tissue cryosections were immunofluorescently imaged for epithelial and immune cell markers. Images were analyzed for total virions, proportion of penetrators, depth of virion penetration, as well as immune cell counts and depths in the tissue. We visualized individual PA virions breaching penile epithelial surfaces in the explant and macaque model. Using kernel density estimated probabilities of localizing a virion or immune cell at certain tissue depths revealed that interactions between virions and cells were more likely to occur in the inner foreskin or glans penis (from local or cadaveric donors, respectively). Using statistical models to account for repeated measures and zero-inflated datasets, we found no difference in total virions visualized at 4 hours between inner and outer foreskins from local donors. At 24 hours, there were more virions in inner as compared to outer foreskin (0.0495 +/- 0.0154 and 0.0171 +/- 0.0038 virions/image, p = 0.001). In the cadaveric specimens, we observed more virions in inner foreskin (0.0507 +/- 0.0079 virions/image) than glans tissue (0.0167 +/- 0.0033 virions/image, p<0.001), but a greater proportion was seen penetrating uncircumcised glans tissue (0.0458 +/- 0.0188 vs. 0.0151 +/- 0.0100 virions/image, p = 0.099) and to significantly greater mean depths (29.162 +/- 3.908 vs. 12.466 +/- 2.985 μm). Our in vivo macaque model confirmed that virions can breach penile squamous epithelia in a living model. In summary, these results suggest that the inner foreskin and glans epithelia may be important sites for HIV transmission in uncircumcised men.
Division of Infectious Diseases, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Minh H
MH
Dinh
Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Meegan R
MR
Anderson
Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Michael D
MD
McRaven
Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Gianguido C
GC
Cianci
Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America; School of Medicine, Deakin University, Melbourne, Australia.
Scott G
SG
McCoombe
Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Z L
ZL
Kelley
Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Casey J
CJ
Gioia
Department of Preventative Medicine, Biostatistical Collaboration Core Center, Northwestern University, Chicago, Illinois, United States of America.
Angela J
AJ
Fought
Department of Preventative Medicine, Biostatistical Collaboration Core Center, Northwestern University, Chicago, Illinois, United States of America.
Alfred W
AW
Rademaker
Department of Comparative Pathology, Tulane National Primate Research Center, Covington, Louisiana, United States of America.
Ronald S
RS
Veazey
Department of Cell & Molecular Biology, Northwestern University Feinberg School of Medicine, Chicago, Illinois, United States of America.
Thomas J
TJ
Hope
D000818:Animals; D002102:Cadaver; D002944:Circumcision, Male; D004847:Epithelial Cells / Q000276:immunology / Q000821:virology*; D005260:Female; D052816:Foreskin / Q000276:immunology / Q000821:virology*; D015658:HIV Infections / Q000276:immunology* / Q000635:transmission*; D015497:HIV-1; D006801:Humans; D007150:Immunohistochemistry; D008253:Macaca mulatta; D008297:Male; D010413:Penis / Q000276:immunology / Q000821:virology