Longitudinal viral shedding and antibody response characteristics of men with acute infection of monkeypox virus: a prospective cohort study.

Understanding of infection dynamics is important for public health measures against monkeypox virus (MPXV) infection. Herein, samples from multiple body sites and environmental fomites of 77 acute MPXV infections (HIV co-infection: N = 42) were collected every two to three days and used for detection of MPXV DNA, surface protein specific antibodies and neutralizing titers. Skin lesions show 100% positivity rate of MPXV DNA, followed by rectum (88.16%), saliva (83.78%) and oropharynx (78.95%). Positivity rate of oropharynx decreases rapidly after 7 days post symptom onset (d.p.o), while the rectum and saliva maintain a positivity rate similar to skin lesions. Viral dynamics are similar among skin lesions, saliva and oropharynx, with a peak at about 6 d.p.o. In contrast, viral levels in the rectum peak at the beginning of symptom onset and decrease rapidly thereafter. 52.66% of environmental fomite swabs are positive for MPXV DNA, with highest positivity rate (69.89%) from air-conditioning air outlets. High seropositivity against A29L (100%) and H3L (94.74%) are detected, while a correlation between IgG endpoint titers and neutralizing titers is only found for A29L. Most indexes are similar between HIV and Non-HIV participants, while HIV and rectitis are associated with higher viral loads in rectum.

Early life inter-kingdom interactions shape the immunological environment of the airways.

BACKGROUND: There is increasing evidence that the airway microbiome plays a key role in the establishment of respiratory health by interacting with the developing immune system early in life. While it has become clear that bacteria are involved in this process, there is a knowledge gap concerning the role of fungi. Moreover, the inter-kingdom interactions that influence immune development remain unknown. In this prospective exploratory human study, we aimed to determine early post-natal microbial and immunological features of the upper airways in 121 healthy newborns. RESULTS: We found that the oropharynx and nasal cavity represent distinct ecological niches for bacteria and fungi. Breastfeeding correlated with changes in microbiota composition of oropharyngeal samples with the greatest impact upon the relative abundance of Streptococcus species and Candida. Host transcriptome profiling revealed that genes with the highest expression variation were immunological in nature. Multi-omics factor analysis of host and microbial data revealed unique co-variation patterns. CONCLUSION: These data provide evidence of a diverse multi-kingdom microbiota linked with local immunological characteristics in the first week of life that could represent distinct trajectories for future respiratory health. TRIAL REGISTRATION: NHS Health Research Authority, IRAS ID 199053. Registered 5 Oct 2016. https://www.hra.nhs.uk/planning-and-improving-research/application-summaries/research-summaries/breathing-together/ Video abstract.

Differential induction of type I and III interferon genes in the upper respiratory tract of patients with coronavirus disease 2019 (COVID-19).

The natural course of type I and III interferon (IFN) response in the respiratory tract of COVID-19 patients needs to be better defined. We showed that type I/III IFNs, IFN-regulatory factor 7 (IRF7), and IFN stimulated genes (ISGs), are highly expressed in the oropharyngeal cells of SARS-CoV-2 positive patients compared to healthy controls. Notably, the subgroup of critically-ill patients that required invasive mechanical ventilation had a general decrease in expression of IFN/ISG genes. Heterogeneous patterns of IFN-I/III response in the respiratory tract of COVID-19 patients may be associated to COVID-19 severity.

Group 1 innate lymphoid-cell-derived interferon-γ maintains anti-viral vigilance in the mucosal epithelium.

The oropharyngeal mucosa serves as a perpetual pathogen entry point and a critical site for viral replication and spread. Here, we demonstrate that type 1 innate lymphoid cells (ILC1s) were the major immune force providing early protection during acute oral mucosal viral infection. Using intravital microscopy, we show that ILC1s populated and patrolled the uninfected labial mucosa. ILC1s produced interferon-γ (IFN-γ) in the absence of infection, leading to the upregulation of key antiviral genes, which were downregulated in uninfected animals upon genetic ablation of ILC1s or antibody-based neutralization of IFN-γ. Thus, tonic IFN-γ production generates increased oral mucosal viral resistance even before infection. Our results demonstrate barrier-tissue protection through tissue surveillance in the absence of rearranged-antigen receptors and the induction of an antiviral state during homeostasis. This aspect of ILC1 biology raises the possibility that these cells do not share true functional redundancy with other tissue-resident lymphocytes.

Effectiveness of the AS04-adjuvanted HPV-16/18 vaccine in reducing oropharyngeal HPV infections in young females-Results from a community-randomized trial.

We studied effectiveness of the AS04-adjuvanted HPV-16/18 (AS04-HPV-16/18) vaccine against human papillomavirus (HPV) oropharyngeal infections associated with the increase of head/neck cancers in western countries. All 38,631 resident adolescents from 1994 to 1995 birth cohorts of 33 Finnish communities were invited in this community-randomized trial (NCT00534638). During 2008-2009, 11,275 girls and 6,129 boys were enrolled in three arms of 11 communities each. In Arm A, 90% of vaccinated girls/boys, and in Arm B, 90% of vaccinated girls received AS04-HPV-16/18 vaccine. Other Arm A/B and all Arm C vaccinated participants received control vaccine. All Arm A participants and Arm B female participants were blinded to vaccine allocation. Oropharyngeal samples were analyzed from 4,871 18.5-year-old females who attended follow-up visit 3-6 years postvaccination. HPV DNA prevalence was determined by SPF-10 LiPA and Multiplex type-specific PCR. Total vaccine effectiveness (VE) was defined as relative reduction of oropharyngeal HPV prevalence in pooled Arms A/B HPV-vaccinated females vs. all Arm C females. VE against oropharyngeal HPV-16/18, HPV-31/45 and HPV-31/33/45 infections were 82.4% (95% confidence intervals [CI]: 47.3-94.1), 75.3% (95%CI: 12.7-93.0) and 69.9% (95% CI: 29.6-87.1), respectively. In conclusion, the AS04-HPV-16/18 vaccine showed effectiveness against vaccine and nonvaccine HPV-types oropharyngeal infections in adolescent females up to 6 years postvaccination.

Oropharyngeal Mother's Milk: State of the Science and Influence on Necrotizing Enterocolitis.

Oropharyngeal administration of mother's own milk-placing drops of milk directly onto the neonate's oral mucosa-may serve to (ex utero) mimic the protective effects of amniotic fluid for the extremely low birth weight infant; providing protection against necrotizing enterocolitis. This article presents current evidence to support biological plausibility for the use of OroPharyngeal Therapy with Mother's Own Milk (OPT-MOM) as an immunomodulatory therapy; an adjunct to enteral feeds of mother's milk administered via a nasogastric or orogastric tube. Current methods and techniques are reviewed, published evidence to guide clinical practice will be presented, and controversies in practice will be addressed.

Identification and characterization of an M cell marker in nasopharynx- and oropharynx-associated lymphoid tissue of sheep.

M cells play a pivotal role in the induction of immune responses within the mucosa-associated lymphoid tissues. M cells exist principally in the follicle-associated epithelium (FAE) of the isolated solitary lymphoid follicles as well as in the lymphoid follicles of nasopharynx-associated lymphoid tissue and gut associated lymphoid tissue (GALT). Through lymphatic cannulation it is possible to investigate local immune responses induced following nasal Ag delivery in sheep. Hence, identifying sheep M cell markers would allow the targeting of M cells to offset the problem of trans-epithelial Ag delivery associated with inducing mucosal immunity. Sheep cDNA from the tonsils of the oropharynx and nasopharynx was PCR amplified using Glycoprotein-2 (GP2)-specific primers and expressed as a poly-His-tagged recombinant sheep GP2 (56 kDa) in HEK293 cells. The recombinant GP2 protein was purified using Ni-NTA affinity chromatography and polyclonal serum against the protein was raised in rats. The antiserum recognized the recombinant sheep GP2 and purified rat IgG against GP2 stained M cells in sections of sheep tonsils from nasopharynx and oropharynx. M cells were found to be present in epithelium of the palatine tonsils (oropharynx), pharyngeal tonsils as well as tubal tonsils (nasopharynx). They were also present in the FAE of the scattered lymphoid follicles over the base of the nasopharynx. Thus, GP2 has been identified to be an important M cell marker of nasopharynx and oropharynx-associated lymphoid tissues in sheep.

Effect of oropharyngeal colostrum therapy in the prevention of necrotising enterocolitis among very low birthweight neonates: A meta-analysis of randomised controlled trials.

BACKGROUND: Necrotising enterocolitis (NEC) is one of the most common life-threatening emergencies of the gastrointestinal tract in preterm neonates. The present study aimed to determine the efficacy of oropharyngeal colostrum with respect to reducing NEC in preterm neonates. METHODS: A literature search was conducted for various randomised control trials by searching the Cochrane Central Register of Controlled Trials, PubMed, EMBASE and ongoing clinical trials. Randomised or quasi-randomised trials comparing oropharyngeal colostrum versus placebo in neonates (birthweight ≤ 1500 g or gestational age ≤ 32 weeks) were included in the review. The methodological quality of each trial was independently reviewed by the authors. For categorical and continuous variables, typical estimates for relative risk and typical estimates for weighted mean difference were calculated, respectively. A random effect model was assumed for meta-analysis. RESULTS: In total, four eligible trials were included in the review. Oropharyngeal colostrum therapy was not associated with a statistically significant reduction in the incidence of NEC stage ≥2 [typical relative risk (RR) = 0.64; 95% confidence interval (CI) = 0.27-1.49], mortality from any cause (typical RR = 0.86; 95% CI = 0.15-4.80) and time to reach full feed [typical weighted mean difference (WMD) = -3.26; 95% CI = -8.87 to 2.35]. Duration of hospital stay was significantly less in the control group (typical WMD = 9.77; 95% CI = 3.96-15.59). CONCLUSIONS: The current evidence is insufficient for recommending oropharyngeal colostrum as a routine clinical practice in the prevention of NEC. We emphasise the need for large randomised controlled trials with an adequate sample size and validated clinical outcomes in preterm neonates.

Signaling by a Conserved Quorum Sensing Pathway Contributes to Growth Ex Vivo and Oropharyngeal Colonization of Human Pathogen Group A Streptococcus.

Bacterial virulence factor production is a highly coordinated process. The temporal pattern of bacterial gene expression varies in different host anatomic sites to overcome niche-specific challenges. The human pathogen group A streptococcus (GAS) produces a potent secreted protease, SpeB, that is crucial for pathogenesis. Recently, we discovered that a quorum sensing pathway comprised of a leaderless short peptide, SpeB-inducing peptide (SIP), and a cytosolic global regulator, RopB, controls speB expression in concert with bacterial population density. The SIP signaling pathway is active in vivo and contributes significantly to GAS invasive infections. In the current study, we investigated the role of the SIP signaling pathway in GAS-host interactions during oropharyngeal colonization. The SIP signaling pathway is functional during growth ex vivo in human saliva. SIP-mediated speB expression plays a crucial role in GAS colonization of the mouse oropharynx. GAS employs a distinct pattern of SpeB production during growth ex vivo in saliva that includes a transient burst of speB expression during early stages of growth coupled with sustained levels of secreted SpeB protein. SpeB production aids GAS survival by degrading LL37, an abundant human antimicrobial peptide. We found that SIP signaling occurs during growth in human blood ex vivo. Moreover, the SIP signaling pathway is critical for GAS survival in blood. SIP-dependent speB regulation is functional in strains of diverse emm types, indicating that SIP signaling is a conserved virulence regulatory mechanism. Our discoveries have implications for future translational studies.

Tissue-specific Differences in Immune Cell Subsets Located in the Naso-oropharyngeal-associated Lymphoid Tissues.

Defining the immune cells within the naso-oropharyngeal-associated lymphoid tissues would promote the development of efficient orally and nasally delivered immunotherapies. The aim was to compare murine antigen-presenting cells (APCs) and T cell subsets in the nose-associated lymphoid tissues (NALT), cervical lymph nodes (CLN), mesenteric lymph nodes (MLN) and peripheral lymph nodes (PLN) using flow cytometry and in vitro proliferation assays. Overall, the NALT contained a higher proportion of APCs and a lower proportion of T cells compared to the CLN, MLN and PLN. The APCs of the NALT more often belonged to the CD11c+ CD11b+ and the CD11cneg CD11b+ subsets as compared to the other sites. Both of these APC populations showed little sign of activation, that is low expression of the markers CD40, CD86 and IAd. Instead, the APCs of the NALT more often co-expressed CX3CR1 and CD206, markers associated with a tolerogenic function. No increase in the proportion of regulatory T cells was observed in the NALT. Instead, the T cells frequently exhibited a memory/effector phenotype, expressing the homing markers α4ß7, CCR4 and CCR9, but rarely the naïve phenotype cell surface marker CD45RB. In contrast, the T cells at the other sites were mostly of the naïve phenotype. In addition, cells from the NALT did not proliferate upon in vitro stimulation with Con A, whereas the cells from the other sites did. Taken together, these results suggest that the NALT is primarily an effector site rather than one for activation and differentiation, despite it being regarded as a site of induction.

Characterization of the oropharynx: anatomy, histology, immunology, squamous cell carcinoma and surgical resection.

Understanding the structure and function of the oropharynx is paramount for providing excellent patient care. In clinical oncology, the oropharynx is generally divided into four distinct components: (i) the base of the tongue; (ii) the soft palate; (iii) the palatine tonsillar fossa; and (iv) the pharyngeal wall. The oropharyngeal mucosa is distinct from other mucosal surfaces in the body, as it is composed of a reticulated epithelium with a discontinuous basement membrane, also known as lymphoepithelium. This review describes the anatomy, histology, immunology and surgical resection of the oropharynx as they relate to oncological care.

Density, Serotype Diversity, and Fitness of Streptococcus pneumoniae in Upper Respiratory Tract Cocolonization With Nontypeable Haemophilus influenzae.

BACKGROUND: Coinfections by Streptococcus pneumoniae and nontypeable Haemophilus influenzae (NTHi) are frequently implicated in complex otitis media. Whereas upper respiratory tract carriage precedes disease for both pathogens, interactions between species in cocolonized hosts are poorly understood. We compared colonization densities and the diversity and fitness of pneumococcal serotypes in single-species and mixed-species colonization. METHODS: We analyzed nasopharyngeal pneumococcal carriage and nasopharyngeal and oropharyngeal NTHi carriage in 13 541 samples collected over 6909 study visits from 769 children 2-30 months old in a 7-valent pneumococcal conjugate vaccine dosing trial. We measured density associations between the species and compared pneumococcal serotype diversity during and in the absence of NTHi colonization. We used logistic regression to quantify associations between NTHi colonization and previously published pneumococcal serotype factors related to fitness. RESULTS: Densities of the 2 species were positively associated when they co-occur in the nasopharynx. NTHi colonization was associated with reduced pneumococcal serotype diversity among children 2-18 months old and was more prevalent among children carrying pneumococcal serotypes with greater capsular thickness, neutrophil resistance, and metabolic efficiency. CONCLUSIONS: Pneumococcal-NTHi cocolonization is associated with an elevated density of both species and with reduced diversity and increased fitness of pneumococcal serotypes. NTHi colonization may create a selective environment favoring pneumococci with immune-evasive phenotypes.

Transforming growth factor-ß1 sustains the survival of Foxp3(+) regulatory cells during late phase of oropharyngeal candidiasis infection.

As CD4(+)CD25(+)Foxp3(+) regulatory T cells (Tregs) play crucial immunomodulatory roles during infections, one key question is how these cells are controlled during antimicrobial immune responses. Mechanisms controlling their homeostasis are central to ensure efficient protection against pathogens, as well as to control infection-associated immunopathology. Here we studied how their viability is regulated in the context of mouse oropharyngeal candidiasis (OPC) infection, and found that these cells show increased protection from apoptosis during late phase of infection and reinfection. Tregs underwent reduced cell death because they are refractory to T cell receptor restimulation-induced cell death (RICD). We confirmed their resistance to RICD, using mouse and human Tregs in vitro, and by inducing α-CD3 antibody-mediated apoptosis in vivo. The enhanced viability is dependent on increased transforming growth factor-ß1 (TGF-ß1) signaling that results in upregulation of cFLIP (cellular FLICE (FADD-like IL-1ß-converting enzyme)-inhibitory protein) in Tregs. Protection from cell death is abrogated in the absence of TGF-ß1 signaling in Tregs during OPC infection. Taken together, our data unravel the previously unrecognized role of TGF-ß1 in promoting Treg viability, coinciding with the pronounced immunomodulatory role of these cells during later phase of OPC infection, and possibly other mucosal infections.

Stromal infiltration of CD8 T cells is associated with improved clinical outcome in HPV-positive oropharyngeal squamous carcinoma.

BACKGROUND: Patients with human papillomavirus (HPV)-positive oropharyngeal squamous cell carcinoma (OPSCC) have a better prognosis than those with HPV-negative tumours. There is interest in de-escalating their treatment but strategies are needed for risk stratification to identify subsets with a poor prognosis. This study investigated tumour-infiltrating lymphocytes (TILs) in relation to HPV tumour status and patient survival. METHODS: Biopsies from 218 patients diagnosed with OPSCC between 2002 and 2011, who underwent chemo/radiotherapy were analysed for HPV by PCR, in-situ hybridisation and p16 immunohistochemistry (IHC). One hundred and thirty-nine samples with concordant HPV detection were analysed for CD3, CD4, CD8 and FoxP3 expression in tumour and stromal regions using multiplexIHC and multispectral image analysis. Labelling of smooth muscle actin (SMA) identified activated stroma. RESULTS: Human papillomavirus-positive compared with HPV-negative OPSCC had higher infiltration in both tumour and stromal areas of CD4 and CD8 T cells but not FoxP3 T regulatory cells. Only CD3+CD8+ stromal and not tumour area infiltration was associated with increased survival (P=0.02). There was significantly higher SMA expression in HPV-positive compared with -negative tumours, which did not correlate with survival. CONCLUSIONS: Studies of TILs for risk stratification in OPSCC should assess stromal infiltration.

Assessment of airway microbiota and inflammation in cystic fibrosis using multiple sampling methods.

RATIONALE: Oropharyngeal (OP) swabs and induced sputum (IS) are used for airway bacteria surveillance in nonexpectorating children with cystic fibrosis (CF). Molecular analyses of these airway samples detect complex microbial communities. However, the optimal noninvasive sampling approach for microbiota analyses and the clinical relevance of microbiota, particularly its relationship to airway inflammation, is not well characterized. OBJECTIVES: The goals of this study were to compare molecular analyses of concurrently collected saliva, OP swabs, IS, and expectorated sputum (ES) from children with CF and to determine the association between microbiota, lung function, and airway inflammation. METHODS: Saliva, OP swabs, IS, and ES were collected from 16 children with CF. Spirometry was performed. MEASUREMENTS AND MAIN RESULTS: Respiratory and saliva samples (n = 61) were sequenced for bacterial microbial communities, and total and CF-specific bacterial quantitative PCR assays were performed. Airway samples underwent conventional culture for CF-specific pathogens. Neutrophil elastase, IL-1ß, IL-1ra, IL-6, Il-8, TNF-α, and vascular endothelial growth factor were measured in ES and IS. Sequencing results from individual subjects were similar across samples, with greater between-subject than within-subject variation. However, Pseudomonas and Staphylococcus were detected in higher relative abundance from lower airways (ES and IS) compared with paired upper airway samples (OP and saliva). Pseudomonas, Staphylococcus, and Enterobacteriaceae correlated with increased airway inflammation. Divergence between microbiota in upper airway compared with lower airway samples, indicating greater differences between communities, was associated with increased sputum neutrophil elastase. CONCLUSIONS: Bacteria detected in IS samples resemble ES samples, whereas OP samples may underrepresent bacteria associated with airway inflammation. Divergence of lower airway communities from upper airway was associated with airway inflammation and may portend disease progression.

The loss of topography in the microbial communities of the upper respiratory tract in the elderly.

RATIONALE: The microbial communities inhabiting the upper respiratory tract protect from respiratory infection. The maturity of the immune system is a major influence on the composition of the microbiome and, in youth, the microbiota and immune system are believed to mature in tandem. With age, immune function declines and susceptibility to respiratory infection increases. Whether these changes contribute to the microbial composition of the respiratory tract is unknown. OBJECTIVES: Our goal was to determine whether the microbes of the upper respiratory tract differ between mid-aged adults (18-40 yr) and the elderly (>65 yr). METHODS: Microbiomes of the anterior nares and oropharynx of elderly individuals were evaluated by 16S rRNA gene sequencing. These communities were compared with data on mid-aged adults obtained from the Human Microbiome Project. MEASUREMENTS AND MAIN RESULTS: The microbiota of the elderly showed no associations with sex, comorbidities, residence, or vaccinations. Comparisons of mid-aged adults and the elderly demonstrated significant differences in the composition of the anterior nares and oropharynx, including a population in the anterior nares of the elderly that more closely resembled the oropharynx than the anterior nares of adults. The elderly oropharyngeal microbiota were characterized by increased abundance of streptococci, specifically, Streptococcus salivarius group species, but not Streptococcus pneumoniae, carriage of which was low (<3% of participants), as demonstrated by PCR (n = 4/123). CONCLUSIONS: Microbial populations of the upper respiratory tract in mid-aged adults and the elderly differ; it is possible that these differences contribute to the increased risk of respiratory infections experienced by the elderly.

Comparison of the prevalence of common bacterial pathogens in the oropharynx and nasopharynx of gambian infants.

BACKGROUND: CRM- based pneumococcal conjugate vaccines generally have little impact on the overall prevalence of pneumococcal carriage because of serotype replacement. In contrast, protein vaccines could substantially reduce the overall prevalence of pneumococcal carriage with potential microbiological and clinical consequences. Therefore, trials of pneumococcal protein vaccines need to evaluate their impact on carriage of other potentially pathogenic bacteria in addition to the pneumococcus. METHODS: As a prelude to a trial of an investigational pneumococcal vaccine containing pneumococcal polysaccharide conjugates and pneumococcal proteins, the prevalence of carriage of Streptococcus pneumoniae, Haemophilus influenzae, Moraxella species and Staphylococcus aureus in the nasopharynx of 1030 Gambian infants (median age 35 weeks) was determined. An oropharyngeal swab was obtained at the same time from the first 371 infants enrolled. Standard microbiological techniques were used to evaluate the bacterial flora of the pharynx and to compare that found in the oropharynx and in the nasopharynx. RESULTS: The overall pneumococcal carriage rate was high. Isolation rates of S. pneumoniae and Moraxella species were significantly higher using nasopharyngeal rather than oropharyngeal swabs (76.1% [95% CI 73.4%,78.7%] vs. 21.3% [95% CI 17.2%,25.8%] and 48.9% [95% CI 45.8%, 52.0%] vs. 20.5% % [95% CI 16.5%,25.0%] respectively). In contrast, S. aureus and H. influenzae were isolated more frequently from oropharyngeal than from nasopharyngeal swabs (65.0% [95% CI 59.9%, 69.8%] vs. 33.6% [95% CI 30.7%, 36.5%] and 31.8% [95% CI 16.5%, 25.0%] vs. 22.4% [95% CI 19.9%, 25.1%] respectively). No group A ß haemolytic streptococci were isolated. CONCLUSION: Collection of an oropharyngeal swab in addition to a nasopharyngeal swab will provide little additional information on the impact of a novel pneumococcal vaccine on pneumococcal carriage but it might provide additional, valuable information on the impact of the vaccine on the overall microbiota of the pharynx.

Intraocular vaccination with an inactivated highly pathogenic avian influenza virus induces protective antibody responses in chickens.

Because it is expected to induce cross-reactive serum and mucosal antibody responses, mucosal vaccination against highly pathogenic avian influenza (HPAI) is potentially superior to conventional parenteral vaccination. Here, we tested whether intraocular vaccination with an inactivated AI virus induced protective antibody responses in chickens. Chickens were inoculated intraocularly twice with 10(4) hemagglutination units of an inactivated H5N1 HPAI virus. Four weeks after the second vaccination, the chickens were challenged with a lethal dose of the homologous H5N1 HPAI virus. Results showed that most of the vaccinated chickens mounted positive antibody responses. The median serum hemagglutination inhibition titer was 1:80. Addition of CpG oligodeoxynucleotide 2006 or cholera toxin to the vaccine did not enhance serum antibody titers. Cross-reactive anti-hemagglutinin IgG, but not IgA, was detected in oropharyngeal secretions. In accordance with these antibody results, most vaccinated chickens survived a lethal challenge with the H5N1 HPAI virus and did not shed the challenge virus in respiratory or digestive tract secretions. Our results show that intraocular vaccination with an inactivated AI virus induces not only systemic but also mucosal antibody responses and confers protection against HPAI in chickens.

Th17 cells confer long-term adaptive immunity to oral mucosal Candida albicans infections.

Oropharyngeal candidiasis (OPC) is an opportunistic infection caused by Candida albicans. Despite its prevalence, little is known about C. albicans-specific immunity in the oral mucosa. Vaccines against Candida generate both T helper type 1 (Th1) and Th17 responses, and considerable evidence implicates interleukin (IL)-17 in immunity to OPC. However, IL-17 is also produced by innate immune cells that are remarkably similar to Th17 cells, expressing the same markers and localizing to similar mucosal sites. To date, the relative contribution(s) of Th1, Th17, and innate IL-17-producing cells in OPC have not been clearly defined. Here, we sought to determine the nature and function of adaptive T-cell responses to OPC, using a new recall infection model. Mice subjected to infection and re-challenge with Candida mounted a robust and stable antigen-specific IL-17 response in CD4+ but not CD8+ T cells. There was little evidence for Th1 or Th1/Th17 responses. The Th17 response promoted accelerated fungal clearance, and Th17 cells could confer protection in Rag1-/- mice upon adoptive transfer. Surprisingly, CD4 deficiency did not cause OPC but was instead associated with compensatory IL-17 production by Tc17 and CD3+CD4-CD8- cells. Therefore, classic CD4+Th17 cells protect from OPC but can be compensated by other IL-17-producing cells in CD4-deficient hosts.