Table 2.

Evidence for secreted factors in resistance to mucosal human immunodeficiency virus (HIV)-1 infection

Exposure route	Cohort types	Cohort definition	Immune-mediated mechanism(s) and references
Sexual exposure (male/female)	•Discordant couples	Individuals exposed to HIV-1 via unprotected vaginal intercourse with an HIV-infected person	Mucosal or systemic IgA [5,44–48,52,58–60]CC (β)-chemokines [64,65,67]
	•Sex workers		SLP1, lactoferrin, elafin/trappin-2 [73,74]
			Defensins [79–81]
Sexual exposure (male/male)	•Discordant couples	Individuals exposed to HIV-1 via unprotected anal intercourse with an HIV-infected person	Mucosal or systemic IgA [49,50]
			CC (β)-chemokines [66]
Mother-to-child exposure	•Vertical transmission	Children exposed to HIV-1 through carriage from HIV-1-infected mother	Mucosal or systemic IgA [51]
			Defensins [76,82]
Oral exposure	•Breastfeeding	Children exposed to HIV-1 through nursing.Sexually active adults	Mucosal or systemic IgA [49,50,51]
	•Discordant couples (oral sex)		CC (β)-chemokines [66]

Ig, immunoglobulin.