Human Staphylococcus aureus (SA) nasal carriage provides a reservoir for the dissemination of infectious strains; however, factors regulating the establishment and persistence of nasal colonization are mostly unknown. We measured carriage duration and nasal fluid inflammatory markers after nasally inoculating healthy participants with their previously isolated SA strains. Ten out of 15 studies resulted in rapid clearance (9±6 days) that corresponded with upregulated chemokines, growth factors, and predominantly Th1-type cytokines, but not IL-17. Nasal SA persistence corresponded with elevated baseline levels of MIP-1β, IL-1β, and IL-6, no induction of inflammatory factors post-inoculation, and decreased IL-1RA:IL-1β ratio. SA-expressed staphylococcal protein A (SpA) levels correlated positively with carriage duration. Competitive inoculation studies revealed that isogenic SpA knockout (ΔSpA) strains were cleared faster than wild-type only in participants with upregulated inflammatory markers post-inoculation. The remaining participants did not mount an inflammatory response and did not clear either strain. ΔSpA strains demonstrated lower growth rates in carrier nasal fluids and lower survival rates when incubated with neutrophils. Collectively, the presented studies identify innate immune effectors that cooperatively modulate nasal carriage duration, and confirm SpA as a bacterial co-determinant of SA nasal carriage.

nasal carriage is transient in most humans and usually benign, but dissemination of to extranasal sites causes the majority of clinical infections, and is a major cause of serious infections in the United States. A better understanding of innate nasal decolonization mechanisms is urgently needed, as are relevant models for studying clearance. Here, we screened a population of healthy smokers for nasal carriage and compared the participants' abilities to clear experimentally applied nasal before and after completion of a smoking cessation program. We determined that cigarette smoking increases the mean nasal load (2.6 × 10 CFU/swab) compared to the load observed in healthy nonsmokers (1.7 × 10 CFU/swab) and might increase the rate of nasal carriage in otherwise-healthy adults: 22 of 99 smokers carried at the screening visit, while only 4 of 30 nonsmokers screened positive during the same time period. Only 6 of 19 experimental inoculation studies in active smokers resulted in clearance within the month of follow-up, while in the cessation group, 6 of 9 subjects cleared nasal and carriage duration averaged 21 ± 4 days. Smoking cessation associated with enhanced expression of -associated interleukin-1β (IL-1β) and granulocyte colony-stimulating factor (G-CSF) in nasal fluids. Participants who failed to clear exhibited a higher nasal load and elevated nasal interleukin-1 receptor antagonist (IL-1RA) expression at the preexperiment study visits. We conclude that smokers exhibit higher loads than nonsmokers and that innate immune pathways, including G-CSF expression and signaling through the IL-1 axis, are important mediators of nasal clearance.

nasal carriage is a common condition affecting both healthy and immunocompromised populations and provides a reservoir for dissemination of potentially infectious strains by casual contact. The factors regulating the onset and duration of nasal colonization are mostly unknown, and a human-relevant animal model is needed. Here, we screened 17 pig-tailed macaques () for carriage, and 14 of 17 animals tested positive in the nose at one or both screening sessions (8 weeks apart), while the other 3 animals were negative in the nose but positive in the pharynx at least once. As in humans, colonization was densest in the nose, and treatment of the nostrils with mupirocin ointment effectively cleared the nostrils and 6 extranasal body sites. Experimental nasal colonization was established with 10 CFU/nostril, and both autologous and nonautologous strains survived over 40 days without any apparent adverse effects. A human nasal isolate (strain D579, sequence type 398) was carried in 4 of 6 animals for over 3 weeks. Nostrils that did eradicate experimentally applied exhibited neutrophilic innate immunity marked by elevated nasal interleukin-1β (IL-1β), IL-8, and monocyte chemotactic protein 1 levels and a 10-fold decreased IL-1 receptor antagonist/IL-1β ratio within 7 days postinoculation, analogous to the human condition. Taken together, pig-tailed macaques represent a physiological model of human nasal carriage that may be utilized for testing natural colonization and decolonization mechanisms as well as novel classes of anti- therapeutics.

While extensive research efforts have decreased human immunodeficiency virus (HIV) transmissions and mortalities, new challenges have arisen in the fight to eradicate HIV. Drug resistance to antiretroviral therapy threatens infected individuals, while the prevalence of heterosexual transmission creates an urgent need for therapies effective in the female reproductive tract (FRT) mucosa. We screened a library of 2095 small molecule compounds comprising a unique chemical space, purchased from Asinex Corporation, for antiviral activity against human immunodeficiency virus type 1 (HIV-1) strain BaL and identified several molecular representatives of a unique class of HIV-1 inhibitors, which we termed “Avirulins.” We determined that Avirulins were active against clinical isolates of HIV-1 from genetically variant subtypes, several of which have reduced sensitivity to other antivirals. Avirulins displayed specific dose-dependent inhibition of the HIV-1 drug target, reverse transcriptase (RT). Avirulins were effective against several nucleoside RT-inhibitor resistant strains of HIV-1, as well as one nonnucleoside RT-inhibitor resistant strain containing a 106A mutation, suggesting a noncompetitive mechanism of action. Drugs, which are damaging to the FRT, can increase the risk of HIV-1 transmission. We therefore explored the cytotoxicity of Avirulins against epithelial cells derived from the FRT and found no significant toxicity, even at the highest concentrations tested. Importantly, Avirulin antiviral activity was not diminished in human cervico–vaginal fluid, suggesting retained potency in the milieu of the FRT. Based on these promising results, Avirulins should be valuable chemical scaffolds for development into next-generation treatments and preventatives that target HIV-1.

Staphylococcus aureus (SA) nasal carriage is a common condition effecting both healthy and immunocompromised populations, and provides a reservoir for dissemination of potentially infectious strains by casual contact. Factors regulating the onset and duration of nasal SA colonization are mostly unknown, and a human-relevant animal model is needed. Here, we screened 17 pig-tailed macaques (Macaca nemestrina) for SA carriage, and 14 of 17 animals tested positive in the nose at one or both screening sessions (8 weeks apart), while the other three animals were negative in the nose but positive in the pharynx at least once. Similar to humans, SA colonization was densest in the nose, and treatment of the nostrils with mupirocin ointment effectively cleared the nostrils and 6 extra-nasal body sites. Experimental nasal SA colonization was established with 104 CFU/nostril, and both autologous and non-autologous strains survived over 40 days without any apparent adverse effects. A human nasal SA isolate (D579/ST398) was carried in 4 of 6 animals for over three weeks. Nostrils that did eradicate experimentally applied SA exhibited neutrophilic innate immunity marked by elevated nasal IL-1β, IL-8, and MCP-1, and a 10-fold decreased IL-1RA:IL-1β ratio within 7 days post-inoculation, analogous to the human condition. Taken together, pig-tailed macaques represent a physiological model of human SA nasal carriage with utility for testing natural colonization and decolonization mechanisms, and novel classes of anti-SA therapeutics.