Challenges for vaccination against sexually-transmitted diseases: induction and long-term maintenance of mucosal immune responses in the female genital tract

Neisseria gonorrhoeae vaccines: a contemporary overview

Neisseria gonorrhoeae infection is an important public health issue, with an annual global incidence of 87 million. N. gonorrhoeae infection causes significant morbidity and can have serious long-term impacts on reproductive and neonatal health and may rarely cause life-threatening disease. Global rates of N. gonorrhoeae infection have increased over the past 20 years. Importantly, rates of antimicrobial resistance to key antimicrobials also continue to increase, with the United States Centers for Disease Control and Prevention identifying drug-resistant N. gonorrhoeae as an urgent threat to public health. This review summarizes the current evidence for N. gonorrhoeae vaccines, including historical clinical trials, key N. gonorrhoeae vaccine preclinical studies, and studies of the impact of Neisseria meningitidis vaccines on N. gonorrhoeae infection. A comprehensive survey of potential vaccine antigens, including those identified through traditional vaccine immunogenicity approaches, as well as those identified using more contemporary reverse vaccinology approaches, are also described. Finally, the potential epidemiological impacts of a N. gonorrhoeae vaccine and research priorities for further vaccine development are described.

Immunization with Multiple Virulence Factors Provides Maternal and Neonatal Protection against Group B Streptococcus Serotypes

Group B streptococcus (GBS) commonly colonizes the vaginal tract and is a leading cause of life-threatening neonatal infections and adverse pregnancy outcomes. No effective vaccine is clinically available. Conserved bacterial virulence factors, including those of GBS, have been employed as vaccine components. We investigated serotype-independent protection against GBS by intranasal immunization with six conserved GBS virulence factors (GBSV6). GBSV6 induced systemic and vaginal antibodies and T cell responses in mice. The immunity reduced mouse mortality and vaginal colonization by various GBS serotypes and protected newborn mice of immunized dams against GBS challenge. Intranasal GBSV6 immunization also provided long-lasting protective immunity and had advantages over intramuscular GBSV6 immunization regarding restricting vaginal GBS colonization. Our findings indicate that intranasal immunization targeting multiple conserved GBS virulence factors induces serotype-independent immunity, which protects against GBS infection systemically and vaginally in dams and prevents newborn death. The study presents valuable strategies for GBS vaccine development.

Alginate-coated chitosan microparticles encapsulating an oral plasmid-cured live Salmonella enterica serovar Gallinarum vaccine cause a higher expression of interferon-gamma in chickens compared to the parenteral live vaccine

Salmonella enterica serovar Gallinarum causes a disease in chickens known as fowl typhoid. Interferon-gamma (IFN-γ) has been shown to be crucial in eliminating salmonellosis infection because of its strong association with T-cell responses. This study was undertaken to compare the expression of IFN-γ in chickens generated by different vaccine formulations. Eighty one-day-old Lohmann layer chicks were divided into four groups of 20 birds each for the experiment. This comprised an unvaccinated negative control group (NEG), a group vaccinated with the live 9R vaccine by the injection route (SC), a group vaccinated with alginate-coated chitosan microparticles encapsulating live plasmid-cured S. Gallinarum strain 9 (PC) by the oral route, and a group vaccinated with a weak attenuated live S. Gallinarum strain 9 encapsulated in alginate-coated chitosan microparticles (VM) given orally. Vaccinations were done at 10 and 14 weeks of age followed by challenge at 16 weeks of age. IgG was measured using ELISA. qRT-PCR was used to compare the mRNA fold expression of IFN-γ in the PC, VM and SC groups using the unvaccinated/unchallenged group as the control. There were significant differences in the IgG levels between each vaccinated group and the unvaccinated group (P < 0.05) after booster vaccination and post-challenge. There was 100% protection of the birds in SC and VM groups, 80% protection in PC group and 0% protection in the NEG group. Using 2^-ΔΔCT calculation, IFN-γ was more highly expressed in the PC group than in the SC group or VM group. In conclusion, the IFN-γ was more highly expressed in the PC group (though not significantly higher) compared to the SC and VM groups and this could be attributed to the alginate-coated chitosan microparticles which acted as an adjuvant.

A Bacillus-based Coxsackie virus A16 mucosal vaccine induces strong neutralizing antibody responses

The purpose of this study was to construct a Coxsackie virus A16 (CA16) mucosal vaccine and evaluate its ability to induce immune response. VP1 gene of CA16 was inserted into the genome of Bacillus subtilis via recombination and displayed on the surface of the spores. This Bacillus-based vaccine was used for intranasal immunization of mice and the serum antibody titer was determined by enzyme-linked immunosorbent assay (ELISA). Neutralization activity of the serum from immunized mice was analyzed by an in vitro neutralizing test. VP1 gene was successfully integrated into the genome of Bacillus subtilis and was expressed on the surface of Bacillus spores. Intranasal immunization of mice with this vaccine induced a higher level of VP1 specific IgA and IgG than in mice of the control group (p < 0.05). The neutralizing antibody titer in the spore immunization group was 1 : 169, which was higher than that in the control group (p < 0.05). We concluded that vaccine prepared by displaying CA16 VP1 protein on the surface of Bacillus subtilis spores can stimulate mice to produce protective neutralizing antibodies, which provides foundations for the development of CA16 mucosal vaccine.

Engineering intravaginal vaccines to overcome mucosal and epithelial barriers

The mucosal surface of the vagina is a primary human immunodeficiency virus (HIV) entry portal, making it an attractive site for HIV vaccination. However, HIV vaccines based on recombinant adenovirus (rAd) do not efficiently cross the mucus layers or underlying epithelium of the vagina. Here we designed nanocomplexes of rAd particles coated with (1) the polyethylene glycol derivative APS to provide a hydrophilic surface that would prevent entrapment in the hydrophobic mucus, and (2) the cell-penetrating peptide TAT to improve transduction efficiency. The optimized rAd-TAT-APS nanocomplexes could achieve the balance of effective mucus-penetrating and cellular transduction. Intravaginal delivery of rAd-TAT-APS encoding HIVgag p24 into mice strongly enhanced HIVgag-specific systemic and mucosal immune responses. This rAd-TAT-APS system may allow effective vaginal delivery of vaccines against HIV and other infectious agents.

A Probiotic Adjuvant Lactobacillus rhamnosus Enhances Specific Immune Responses after Ocular Mucosal Immunization with Chlamydial Polymorphic Membrane Protein C

Recent advances in the development of chlamydia vaccines, using live-attenuated or ultraviolet light-inactivated chlamydia, are paving the way for new possibilities to oppose the societal challenges posed by chlamydia-related diseases, such as blinding trachoma. An effective subunit vaccine would mitigate the risks associated with the use of a whole-cell vaccine. Our rationale for the design of an efficient subunit vaccine against Chlamydia trachomatis (Ct) is based on the membrane proteins involved in the initial Ct-host cell contact and on the route of immunization that mimics the natural infection process (i.e., via the ocular mucosa). The first aim of our study was to characterize the specific conjunctival and vaginal immune responses following eye drop immunization in BALB/c mice, using the N-terminal portion of the Ct serovar E polymorphic membrane protein C (N-PmpC) as the subunit vaccine antigen. Second, we aimed to examine the adjuvant properties of the probiotic Lactobacillus rhamnosus (LB) when formulated with N-PmpC. N-PmpC applied alone stimulated the production of N-PmpC- and Ct serovar B-specific antibodies in serum, tears and vaginal washes, whereas the combination with LB significantly enhanced these responses. The N-PmpC/LB combination initiated a T cell response characterized by an elevated percentage of CD25+ T cells and CD8+ effector T cells, enhanced CD4+ T-helper 1 skewing, and increased regulatory T cell responses. Together, these results show that eye drop vaccination with combined use of N-PmpC and a live probiotic LB stimulates specific cellular and humoral immune responses, not only locally in the conjunctiva but also in the vaginal mucosa, which could be a promising approach in Ct vaccine development.

Tissue-resident memory T cells

Tissues such as the genital tract, skin, and lung act as barriers against invading pathogens. To protect the host, incoming microbes must be quickly and efficiently controlled by the immune system at the portal of entry. Memory is a hallmark of the adaptive immune system, which confers long-term protection and is the basis for efficacious vaccines. While the majority of existing vaccines rely on circulating antibody for protection, struggles to develop antibody-based vaccines against infections such as herpes simplex virus (HSV) and human immunodeficiency virus (HIV) have underscored the need to generate memory T cells for robust antiviral control. The circulating memory T-cell population is generally divided into two subsets: effector memory (TEM ) and central memory (TCM ). These two subsets can be distinguished by their localization, as TCM home to secondary lymphoid organs and TEM circulate through non-lymphoid tissues. More recently, studies have identified a third subset, called tissue-resident memory (TRM ) cells, based on its migratory properties. This subset is found in peripheral tissues that require expression of specific chemoattractants and homing receptors for T-cell recruitment and retention, including barrier sites such as the skin and genital tract. In this review, we categorize different tissues in the body based on patterns of memory T-cell migration and tissue residency. This review also describes the rules for TRM generation and the properties that distinguish them from circulating TEM and TCM cells. Finally, based on the failure of recent T-cell-based vaccines to provide optimal protection, we also discuss the potential role of TRM cells in vaccine design against microbes that invade through the peripheral tissues and highlight new vaccination strategies that take advantage of this newly described memory T-cell subset.

Recombinant Salmonella enterica serovar Typhimurium as a vaccine vector for HIV-1 Gag

The HIV/AIDS epidemic remains a global health problem, especially in Sub-Saharan Africa. An effective HIV-1 vaccine is therefore badly required to mitigate this ever-expanding problem. Since HIV-1 infects its host through the mucosal surface, a vaccine for the virus needs to trigger mucosal as well as systemic immune responses. Oral, attenuated recombinant Salmonella vaccines offer this potential of delivering HIV-1 antigens to both the mucosal and systemic compartments of the immune system. So far, a number of pre-clinical studies have been performed, in which HIV-1 Gag, a highly conserved viral antigen possessing both T- and B-cell epitopes, was successfully delivered by recombinant Salmonella vaccines and, in most cases, induced HIV-specific immune responses. In this review, the potential use of Salmonella enterica serovar Typhimurium as a live vaccine vector for HIV-1 Gag is explored.

The association between cytokines and intestinal mucosal immunity among broilers fed on diets supplemented with fluorine

Fluorine (F) bioaccumulation has been reported in the organs and tissues of organisms, including intestine. The intestinal mucosa is very important to the immune development. Meanwhile, cytokines are present in the normal intestinal mucosal and play an important role in the immune function. Thus, changes of the cytokine contents are related to the state of intestinal mucosal immunity. In this study, we investigated the changes in contents of cytokines such as interleukin-2 (IL-2), interleukin-4 (IL-4), interleukin-6 (IL-6), interferon gamma (IFN-γ), and tumor necrosis factor-alpha (TNF-α) induced by dietary high F in the mucosa of different parts of intestines (duodenum, jejunum, and ileum) by enzyme-linked immunosorbent assay. A total of 280 one-day-old healthy avian broilers were randomly divided into four groups and fed on a corn-soybean basal diet as control diet (F 22.6 mg/kg) or the same basal diet supplemented with 400, 800, and 1,200 mg F/kg (high F groups I, II, and III) in the form of sodium fluoride for 42 days. The experimental data showed that the contents of IL-2, IL-4, IL-6, IFN-γ, and TNF-α in the intestinal mucosa were significantly decreased in the high F groups II and III when compared with those of the control group from 14 to 42 days of age. It was concluded that dietary F in the range of 800-1,200 mg/kg significantly reduced the contents of aforementioned cytokines in the intestinal mucosa of broilers, which could impact the function of intestinal mucosal immunity through the pathways that decreased the lymphocyte population and/or lymphocyte activation.

Mucosal herpes immunity and immunopathology to ocular and genital herpes simplex virus infections

Herpes simplex viruses type 1 and type 2 (HSV-1 and HSV-2) are amongst the most common human infectious viral pathogens capable of causing serious clinical diseases at every stage of life, from fatal disseminated disease in newborns to cold sores genital ulcerations and blinding eye disease. Primary mucocutaneous infection with HSV-1 & HSV-2 is followed by a lifelong viral latency in the sensory ganglia. In the majority of cases, herpes infections are clinically asymptomatic. However, in symptomatic individuals, the latent HSV can spontaneously and frequently reactivate, reinfecting the muco-cutaneous surfaces and causing painful recurrent diseases. The innate and adaptive mucosal immunities to herpes infections and disease remain to be fully characterized. The understanding of innate and adaptive immune mechanisms operating at muco-cutaneous surfaces is fundamental to the design of next-generation herpes vaccines. In this paper, the phenotypic and functional properties of innate and adaptive mucosal immune cells, their role in antiherpes immunity, and immunopathology are reviewed. The progress and limitations in developing a safe and efficient mucosal herpes vaccine are discussed.

B cell and T cell immunity in the female genital tract: potential of distinct mucosal routes of vaccination and role of tissue-associated dendritic cells and natural killer cells

The female genital mucosa constitutes the major port of entry of sexually transmitted infections. Most genital microbial pathogens represent an enormous challenge for developing vaccines that can induce genital immunity that will prevent their transmission. It is now established that long-lasting protective immunity at mucosal surfaces has to involve local B-cell and T-cell effectors as well as local memory cells. Mucosal immunization constitutes an attractive way to generate systemic and genital B-cell and T-cell immune responses that can control early infection by sexually transmitted pathogens. Nevertheless, no mucosal vaccines against sexually transmitted infections are approved for human use. The mucosa-associated immune system is highly compartmentalized and the selection of any particular route or combinations of routes of immunization is critical when defining vaccine strategies against genital infections. Furthermore, mucosal surfaces are complex immunocompetent tissues that comprise antigen-presenting cells and also innate immune effectors and non-immune cells that can act as 'natural adjuvants' or negative immune modulators. The functions of these cells have to be taken into account when designing tissue-specific antigen-delivery systems and adjuvants. Here, we will discuss data that compare different mucosal routes of immunization to generate B-cell and T-cell responses in the genital tract, with a special emphasis on the newly described sublingual route of immunization. We will also summarize data on the understanding of the effector and induction mechanisms of genital immunity that may influence the development of vaccine strategies against genital infections.

Is there a role for immunocontraception?

The world's population is continuing to grow at an alarming rate and yet no novel methods of contraception have been introduced since 1960s. The paucity of our current contraceptive armoury is indicated by the 46 million abortions that are performed each year, largely in developing countries where population growth is greatest. Thus, whatever new forms of fertility control we develop for the next millennium, the particular needs of developing countries should be borne in mind. Contraceptive vaccines have the potential to provide safe, effective, prolonged, reversible protection against pregnancy in a form that can be easily administered in the Third World. In this review we consider the contraceptive targets that might be pursued, how vaccines might be engineered and the problems generated by inter-individual variations in antibody titre. We conclude that the specifications for a safe, effective, reversible vaccine are more likely to be met in animals than man.

Mucosal treatments for herpes simplex virus: insights on targeted immunoprophylaxis and therapy

Herpes simplex virus (HSV) serotypes 1 and 2 establish lifelong infections that can produce reactivated pools of virus at mucosal sites where primary infections were initiated. No approved vaccines are available. To break the transmission cycle, interventions must either prevent infection or reduce infectivity at mucosal sites. This article discusses the recent experimental successes of immunoprophylactic and therapeutic compounds that enhance resistance and/or reduce viral loads at genital and ocular mucosa. Current data indicate Toll-like receptor agonists and selected immunomodulating compounds effectively increase the HSV infection threshold and hold promise for genital prophylaxis. Similarly, immunization at genital and extragenital mucosal sites is discussed. Finally, preclinical success with novel immunotherapies for ocular HSV that address herpetic keratitis and corneal blindness is reviewed.

[Experimental vaccines for sexually transmitted infections]

INTRODUCTION

Sexually transmitted infections (STIs) are major global public health problems. Present strategies for prevention have limitations. Vaccines are an attractive addition to the current prevention armamentarium because they provide durable protection and do not require repetitive adherence to be effective. Challenges for vaccination include induction and long-term maintenance of mucosal immune responses in the female genital tract.

VACCINES

A REALISTIC GOAL? For the time being, US Centers for Disease Control and Prevention have recommended only hepatitis and HPV immunization to be routinely offered. Final, III stage trials are underway on other prophylactic vaccines for human papillomavirus and genital herpes. Though vaccines against Chlamydia trachomatis and Neisseria gonorrhoeae are in early stages of development they do offer the hope of preventing pelvic inflammations. The high incidence of HIV-infection for which a vaccine would not be readily available, "cries out" for an effective vaccine.

VACCINES FOR HPV INFECTIONS

According to a recent meta-analysis of worldwide prevalence data, vaccinating with HPV-16/18 VLP against HPV-16 and HPV-18 could prevent over 70% of invasive cervical cancer worldwide. The latest release of data from the phase III trial of a quadrivalent recombinant non-infectious vaccine HPV-6/11/16/18 L1 VLP, including HPV types 6, 11, 16, 18 have given complete protection against HPV-16/18-related cervical intraepithelial neoplasias 1, 2/3, and adenocarcinoma in situ and cancer through 2 years of post-vaccination follow up.

CONCLUSION

Despite the fact that the development of vaccines for STI prevention was rather slow in the past, the ideal vaccine would decrease transmission of the infection between partners and would prevent complications of disease. Moreover, in future decades, increasingly successful universal vaccination of newborns and children will substantially reduce the need for vaccination of persons with specific risk factors, including sexual risk.

Immunization with a bivalent adenovirus-vectored tuberculosis vaccine provides markedly improved protection over its monovalent counterpart against pulmonary tuberculosis

Recombinant virus-vectored vaccines hold great promise for tuberculosis (TB) vaccination strategies. However, there is a lack of side-by-side comparative investigations to dissect the functional differences and support the advantage of multivalent virus-vectored vaccine over its monovalent counterpart. We previously successfully developed a monovalent adenovirus (Ad)-vectored vaccine expressing Ag85a (AdAg85a) and demonstrated its superior protective efficacy in models of pulmonary TB. In this study, we have developed a bivalent Ad TB vaccine expressing Ag85a and TB10.4 antigens as a fusion protein (AdAg85a:TB10.4) and compared its T-cell-activating and immune protective efficacy with that by monovalent AdAg85a. A single intranasal (i.n.) administration of AdAg85a:TB10.4 induced robust T-cell responses toward the respective antigens within the airway lumen and spleen, although the level of Ag85a-specific T-cell responses in the airway lumen triggered by bivalent AdAg85a:TB10.4 was lower than that by its monovalent counterpart at earlier time points. Thus, a single i.n. delivery of AdAg85a:TB10.4 conferred a markedly improved and sustained level of protection in the lung against Mycobacterium tuberculosis (M.tb) challenge over that by AdAg85a or by conventional BCG immunization with similarly induced levels of protection in the spleen. Our results indicate a unique advantage of multivalent viral-vectored TB vaccines for immunization against pulmonary TB.

A genital tract peptide epitope vaccine targeting TLR-2 efficiently induces local and systemic CD8+ T cells and protects against herpes simplex virus type 2 challenge

The next generation of needle-free mucosal vaccines is being rationally designed according to rules that govern the way in which the epitopes are recognized by and stimulate the genital mucosal immune system. We hypothesized that synthetic peptide epitopes extended with an agonist of Toll-like receptor 2 (TLR-2), that are abundantly expressed by dendritic and epithelial cells of the vaginal mucosa, would lead to induction of protective immunity against genital herpes. To test this hypothesis, we intravaginally (IVAG) immunized wild-type B6, TLR-2 (TLR2(-/-)) or myeloid differentiation factor 88 deficient (MyD88(-/-)) mice with a herpes simplex virus type 2 (HSV-2) CD8+ T-cell peptide epitope extended by a palmitic acid moiety (a TLR-2 agonist). IVAG delivery of the lipopeptide generated HSV-2-specific memory CD8+ cytotoxic T cells both locally in the genital tract draining lymph nodes and systemically in the spleen. Moreover, lipopeptide-immunized TLR2(-/-) and MyD88(-/-) mice developed significantly less HSV-specific CD8+ T-cell response, earlier death, faster disease progression, and higher vaginal HSV-2 titers compared to lipopeptide-immunized wild-type B6 mice. IVAG immunization with self-adjuvanting lipid-tailed peptides appears to be a novel mucosal vaccine approach, which has attractive practical and immunological features.

Psychological stress impairs the local CD8+ T cell response to mucosal HSV-1 infection and allows for increased pathogenicity via a glucocorticoid receptor-mediated mechanism

Psychological stress and its associated increases in corticosterone are generally immunosuppressive and contribute to increased herpes simplex virus (HSV)-associated pathogenicity. However, the impact of stress on local control of the initial mucosal-based HSV infection has not been elucidated, nor have the ramifications of such failures of the immune response in terms of viral spread. To address these gaps in knowledge, the studies described herein sought to determine how psychological stress and associated increases in corticosterone may increase susceptibility to HSV encephalitis by allowing for increased viral titers at the site of initial infection. We have shown that in mice intranasally infected with HSV-1, a cell-mediated immune response occurs in the nasopharyngeal-associated lymphoid tissue (NALT), mediastinal lymph nodes (MLN), and superficial cervical lymph nodes (CLN). However, psychological stress induced by restraint decreased the number of lymphocytes in these tissues in HSV-infected mice. Surprisingly, the effects of this restraint stress on HSV-specific CTL function varied by immune tissue. Increased viral titers were found in the nasal cavity of stressed mice, an observation which correlated with an increased CD8+ cell response in the CLN. These findings led us to extend our studies to also determine the ramifications of decreased numbers of locally derived lymphocytes on viral titers following infection. Using an approach in which the NALT was surgically removed prior to infection, we confirmed that decreased numbers of NALT-derived lymphocytes at the time of infection allows for increased viral replication. We conclude that the increased viral titers observed in mice experiencing psychological stress are the consequence of a glucocorticoid-mediated reduction in the numbers of lymphocytes responsible for resolving the initial infection.

New pre-pandemic influenza vaccines: an egg- and adjuvant-independent human adenoviral vector strategy induces long-lasting protective immune responses in mice

Highly pathogenic avian H5N1 influenza viruses that are currently circulating in southeast Asia may acquire the potential to cause the next influenza pandemic. A number of alternate approaches are being pursued to generate cross-protective, dose-sparing, safe, and effective vaccines, as traditional vaccine approaches, i.e., embryonated egg-grown, are not immunogenic. We developed a replication-incompetent adenoviral vector-based, adjuvant- and egg-independent pandemic influenza vaccine strategy as a potential alternative to conventional egg-derived vaccines. In this paper, we address suboptimal dose and longevity of vaccine-induced protective immunity and demonstrate that a vaccine dose as little as 1 x 10(6) plaque-forming unit (PFU) is sufficient to induce protective immune responses against a highly pathogenic H5N1 virus. Furthermore, the vaccine-induced humoral and cellular immune responses and protective immunity persisted at least for a year.

Gonococcal transferrin binding protein chimeras induce bactericidal and growth inhibitory antibodies in mice

We have previously demonstrated the full-length gonococcal transferrin binding proteins (TbpA and TbpB) to be promising antigens in the development of a protective vaccine against Neisseria gonorrhoeae. In the current study we employed a genetic chimera approach fusing domains from TbpA and TbpB to the A2 domain of cholera toxin, which naturally binds in a non-covalent fashion to the B subunit of cholera toxin during assembly. For one construct, the N-terminal half of TbpB (NB) was fused to the A2 subunit of cholera toxin. In a second construct, the loop 2 region (L2) of TbpA was genetically fused between the NB domain and the A2 domain, generating a double chimera. Both chimeras were immunogenic and induced serum bactericidal and vaginal growth-inhibiting antibodies. This study highlights the potential of using protective epitopes instead of full-length proteins in the development of an efficacious gonococcal vaccine.

Microparticles for oral delivery of vaccines

Nonreplicating antigens are poorly immunogenic when given orally, either due to their degradation in the gastrointestinal tract or because they are not efficiently taken up in the gut. Studies in laboratory animals have clearly demonstrated that microparticles can significantly improve the immunogenicity of orally administered antigens. However, the oral delivery of vaccines using microparticles has not been explored extensively in humans and large animals. In this article the progress in oral microparticle antigen delivery will be reviewed and, where possible, studies in humans and large animals will be highlighted. In addition, possible approaches that have the potential to significantly improve microparticle delivery of oral vaccines will be suggested.

Intranasal administration of recombinant Neisseria gonorrhoeae transferrin binding proteins A and B conjugated to the cholera toxin B subunit induces systemic and vaginal antibodies in mice

The transferrin binding proteins (TbpA and TbpB) comprise the gonococcal transferrin receptor and are considered potential antigens for inclusion in a vaccine against Neisseria gonorrhoeae. Intranasal (IN) immunization has shown promise in development of immunity against sexually transmitted disease pathogens, in part due to the induction of antigen-specific genital tract immunoglobulin A (IgA) and IgG. Conjugation of antigens to the highly immunogenic cholera toxin B subunit (Ctb) enhances antibody responses in the serum and mucosal secretions following IN vaccination. In the current study, we characterized the anti-Tbp immune responses following immunization of mice IN with recombinant transferrin binding proteins (rTbpA and rTbpB) conjugated to rCtb. We found that both rTbpA-Ctb and rTbpB-Ctb conjugates administered IN induced antibody responses in the serum and genital tract. IN immunization resulted in both IgA and IgG in the genital tract; however, subcutaneous immunization mainly generated IgG. Surprisingly, rTbpA alone was immunogenic and induced serum and mucosal antibody responses similar to those elicited against the rTbpA-Ctb conjugate. Overall, rTbpB was much more immunogenic than rTbpA, generating serum IgG levels that were greater than those elicited against rTbpA. Bactericidal assays conducted with sera collected from mice immunized IN with TbpA and/or TbpB indicated that both antigens generated antibodies with bactericidal activity. Anti-TbpA antibodies were cross-bactericidal against heterologous gonococcal strains, whereas TbpB-specific antibodies were less cross-reactive. By contrast, antibodies elicited via subcutaneous immunization were not cross-bactericidal against heterologous strains, indicating that IN vaccination could be the preferred route for elicitation of biologically functional antibodies.

Adenoviral Vectors for Mucosal Vaccination Against Infectious Diseases

Adenoviral vector has been extensively studied as a vaccine platform because of its ability to induce potent cellular and humoral immunity. One main advantage of adenoviral vectors is their natural tropism for mucosal surfaces, which makes them ideal for the purpose of mucosal vaccination against pathogens that preferentially initiate infection at the mucosal site. The current understanding of mucosal immunity suggests that mucosal vaccination is far superior to parenteral vaccination in protecting mucosal surfaces. Mucosal vaccination is particularly relevant to those infections for which parenteral immunization strategies have failed to confer protection. This review examines the use of adenoviral vector at mucosal sites for infectious disease against which the current vaccination strategies have been unsuccessful in eliciting protection. Data from animal models have suggested that adenoviral vectors are effective in protecting against infections caused by HIV, herpes simplex virus and Mycobacterium tuberculosis. We believe that these encouraging results will lead to further evaluation in clinical trials in the near future.

Intravaginal immunization with viral subunit protein plus CpG oligodeoxynucleotides induces protective immunity against HSV-2

Although the genital tract has been considered a poor inductive site for immunization with non-replicating antigens, genital immunization may be important for protection against sexually transmitted infections. Recently, we and others showed that CpG oligodeoxynucleotides (ODNs) serve as potent adjuvants for mucosal immunization. The purpose of this study was to determine whether intravaginal (IVAG) immunization with recombinant glycoprotein B (rgB) of herpes simplex virus type 2 (HSV-2) plus CpG ODN can induce specific immunity and protect against genital HSV-2 challenge. C57BL/6 mice were immunized IVAG with rgB plus CpG ODN, rgB plus non-CpG ODN, or rgB alone and challenged IVAG with HSV-2. Mice immunized with rgB + CpG had higher levels of anti-gB IgA and IgG in the vaginal washes and serum compared to mice immunized with rgB alone. Mice immunized with rgB + CpG also had the highest levels of gB-specific IgG in the nasal washes, however no specific IgA was detected in the nasal washes of any group. Mice immunized IVAG with rgB + CpG showed higher survival and lower pathology scores following genital HSV-2 challenge than mice immunized with rgB + non-CpG ODN or rgB alone. Additionally, vaginal viral titers were lower in the rgB + CpG group after infection. These results clearly show that the genital tract is capable of generating a protective immune response after local intravaginal immunization and that a non-replicating antigen is able to induce such a response when administered with an appropriate adjuvant.

Mucosal and systemic anti-HIV responses in rhesus macaques following combinations of intranasal and parenteral immunizations

There is an urgent need to develop vaccines that can elicit immunological memory responses against HIV. Using the rhesus macaque model and a combination of intranasal (IN) and parenteral immunizations with DNA or protein adsorbed to microparticles or mixed with mucosal adjuvants we sought to induce anti-HIV memory-type immune responses in both the mucosal and systemic compartments. Prime/boost immunizations were performed through five IN immunizations alone with HIV-env oligomeric gp140 (Ogp140) or HIV-gag-p24 mixed with Escherichia coli heat labile-derived mutant adjuvants or two parenteral immunizations with DNA encoding HIV-env or -gag adsorbed to microparticles followed by three IN immunizations with p24 gag protein and the mutant adjuvants. Both modes of immunizations induced anti-gp140 plasma and vaginal IgG and IgA as well as interferon (IFN)-gamma secreting peripheral blood mononuclear cells (PBMC) after HIV-env and -gag peptide restimulation. After a resting period of 4 months, when the levels of humoral and cellular responses had decreased, intramuscular (IM) booster immunizations with p55-gag protein adsorbed to microparticles and Ogp140 in MF59 oil in water emulsion significantly enhanced anti-HIV plasma and vaginal antibody, as well as peripheral blood IFN-gamma responses in all groups of vaccinated macaques. Importantly, plasma neutralization activity against both homologous and heterologous HIV strains was observed in all groups following the IM booster immunizations with protein. These findings show that IN priming alone or combinations of parenteral and IN immunizations followed by IM booster immunizations hold promise to significantly enhance mucosal and systemic memory-type immune responses against HIV-1 antigens.

Influence of the Murine Oestrous Cycle on the Induction of Mucosal Immunity

PROBLEM

To determine if the stage of oestrous cycle, at the time of immunization, affects the magnitude of mucosal and systemic immunity.

METHOD OF STUDY

Female BALB/c mice were immunized with tetanus toxoid and cholera toxin by the oral, intranasal and transcutaneous routes. Groups of mice were immunized at proestrus, oestrus, postestrus and diestrus. Antibodies in serum and mucosal secretions were determined by ELISA and T cell responses by lymphocyte proliferation assay.

RESULTS

Oral immunization at the oestradiol dominant stage of cycle (oestrus and proestrus) significantly enhanced TT-specific IgG and IgA levels in female reproductive tract (FRT) secretions and TT-specific IgA levels in faecal extracts. Transcutaneous immunization at diestrus enhanced TT-specific IgG in faecal extracts. TT-specific T cell proliferation is greatest following intranasal immunization at proestrus and transcutaneous immunization at diestrus, particularly in the caudal and lumbar lymph nodes draining the FRT and colon.

CONCLUSIONS

Reproductive cycle-associated changes in the endogenous sex hormones oestradiol and progesterone influence the levels of vaccine-induced immunity in the FRT and distal colon following oral and transcutaneous immunization.

Contraceptive vaccines

The control of human fertility would be revolutionised by the development of a safe, effective, long-acting contraceptive vaccine. The pursuit of this objective has involved the selection of appropriate targets within the reproductive process that are amenable to interference with antibodies. To date, three major targets have been researched. The zona pellucida (ZP) plays key roles in folliculogenesis, fertilisation and early development, and is comprised of powerful cell-specific antigens. The induction of infertility requires high ZP antibody titres that are difficult to maintain without inducing ovarian pathology characterised by a premature loss of primordial follicles. As a premature menopause would be a high price to pay for long-term contraception, this approach to a vaccine cannot progress until the cause of the ovarian pathology has been resolved. Sperm surface antigens represent another promising approach to contraceptive vaccine development. While there is some clinical data to support the likely efficacy of this strategy, none of the gamete-specific molecules characterised to date have fulfilled this promise. Anti-human chorionic gonadotropin (hCG) vaccines terminate pregnancy by preventing the maternal recognition of pregnancy. This vaccine has reached the stage of clinical trials, and preliminary indications are that the approach is safe and potentially effective. However, reliability may be an issue, given the observed inter-individual variability in antibody generation. The future of contraceptive vaccine development will clearly involve a continuation of the intense search for suitable targets and the development of improved immunisation procedures that exploit the latest innovations in vaccine technology.

Mucosal immunity of the adolescent female genital tract

This study sought to characterize mucosal immunity of the adolescent genital tract during the cycle and determine if adolescents have more suppressed immunoglobulin levels in the follicular phase than adults. Daily from cycle day 9 until ovulation, then every other day until menses, cervical secretions for IgA, IgG, and cytokines were collected via Weck-Cel sponge and serum for luteinizing hormone (LH), estradiol, and progesterone was obtained from three adolescent girls (mean age 16.8 years). Immunoglobulin and cytokine levels varied during the menstrual cycle, reaching their nadir around ovulation. Compared with 13 adults, adolescents had a greater drop in IgG in the follicular phase (mean beta-953 vs. -269 microg/mL/day, p = .045), but a similar rate of rise in IgG in the luteal phase (mean beta +118 vs. +100 microg/mL/day, p = .252). Rates of change in IgA did not differ between adolescents and adults for either phase. Although limited by the small sample size, these findings suggest that adolescents may be more sensitive to unopposed estrogen and warrant further investigation.

Both mucosal and systemic routes of immunization with the live, attenuated NYVAC/simian immunodeficiency virus SIV(gpe) recombinant vaccine result in gag-specific CD8(+) T-cell responses in mucosal tissues of macaques

As most human immunodeficiency virus (HIV) infection occurs via mucosal surfaces, an important goal of vaccination may be the induction of virus-specific immune responses at mucosal sites to contain viral infection early on. Here we designed a study in macaques carrying the major histocompatibility complex class I Mamu-A(*)01 molecule to assess the capacity of the highly attenuated poxvirus NYVAC/simian immunodeficiency virus (SIV) SIV(gpe) vaccine candidate administered by the intranasal, intramuscular, or intrarectal route to induce mucosal immunity. All macaques, including one naive macaque, were exposed to SIV(mac251) by the intrarectal route and sacrificed 48 h after infection. The kinetics of immune response at various time points following immunization with NYVAC/SIV(gpe) and the anamnestic response to SIV(mac251) at 48 h after challenge were assessed in blood, in serial rectal and vaginal biopsy samples, and in tissues at euthanasia with an SIV(mac) Gag-specific tetramer. In addition, at euthanasia, antigen-specific cells producing gamma interferon or tumor necrosis factor alpha from the jejunum lamina propria were quantified in all macaques. Surprisingly, antigen-specific CD8(+) T cells were found in the mucosal tissues of all immunized macaques regardless of whether the vaccine was administered by a mucosal route (intranasal or intrarectal) or systemically. In addition, following mucosal SIV(mac251) challenge, antigen-specific responses were mainly confined to mucosal tissues, again regardless of the route of immunization. We conclude that immunization with a live vector vaccine results in the appearance of CD8(+) T-cell responses at mucosal sites even when the vaccine is delivered by nonmucosal routes.

Slight influence of the estrous cycle stage on the mucosal and systemic specific antibody response induced after vaginal and intraperitoneal immunization with protoxin Cry1Ac from Bacillus thuringiensis in mice

Since the immune response appears to be variable according to the hormonal stage of the mammalian female, the aim of this study was to determine whether estrous cycle stage modifies the mucosal and systemic immune responses induced by intraperitoneal and vaginal immunization of mice with protoxin Cry1Ac. We tested the influence of three immunizations on the specific antibody response elicited at estrus and diestrus, that were the same estrous cycle stages at which the antigen was applied. Both intraperitoneal and vaginal immunization of mice with Cry1Ac either at estrus or diestrus induces specific antibody responses at serum, vagina and large intestine. The stage of the estrous cycle have little or non influence in the magnitude of the response induced, since only at serum the IgM was slightly higher at estrus than at diestrus by both routes. At the large intestine only the IgA response elicited via the intraperitoneal route changed, being higher at diestrus, whereas at the vagina IgA response induced did not change significantly due to the cycle stage. Present results suggest that Cry1Ac may be used as an antigen carrier as it can elicit antibody responses at systemic level and at several mucosal sites including the vagina that are not modified significantly throughout the reproductive cycle.

Mucosal DNA vaccination with highly attenuated Shigella is superior to attenuated Salmonella and comparable to intramuscular DNA vaccination for T cells against HIV

An immunization strategy using attenuated bacteria to deliver DNA vaccine plasmids to mucosal sites may induce protective T cell responses against sexual HIV transmission. In a murine intranasal (i.n.) immunization model, we demonstrate that transiently persistent Deltaasd Shigella flexneri strain 15D harboring DNA vaccines induces HIV- and SIV-specific gamma interferon (IFN-gamma) producing CD8+ T cells among splenocytes more efficiently than either a longer persisting DeltaaroD Salmonella typhimurium strain SL7207 or transiently persistent S. typhi strain Ty21a harboring DNA vaccines. Also, the frequency of antigen-specific gamma interferon (IFN-gamma) producing cells induced by Shigella 15D harboring a DNA vaccine were comparable to that induced by intramuscular (i.m.) immunization with purified DNA vaccine. Moreover, the magnitude of mucosal and systemic antigen-specific IgA and IgG responses after immunization were dependent upon the route (i.m. vs. i.n.) of inoculation, with i.n. Shigella 15D DNA vaccines generating higher levels of HIV-specific IgA in vaginal washings than i.m. purified DNA vaccine. Deltaasd S. flexneri is a promising vector for mucosal DNA vaccine immunization against HIV.

The effects of stress on memory cytotoxic T lymphocyte-mediated protection against herpes simplex virus infection at mucosal sites

Psychological stress has been shown to affect many components of the innate and adaptive immune responses to a variety of pathogens including herpes simplex virus (HSV). Mucosal tissues are clinically relevant sites of infection with HSV as well as with many other common pathogens. However, there is a scarcity of experimental evidence that stress affects mucosal immunity. We have taken advantage of a murine model of HSV-specific immune protection that is mediated by only memory cytotoxic T lymphocytes (CTLm) specific for a single CTL recognition epitope within glycoprotein B of HSV-1 (gB498-505). This CTLm population is elicited by vaccination with a recombinant vaccinia virus, which expresses this epitope in the absence of any other HSV-encoded antigens. We report here that stress reduces the ability of gB498-505-specific CTLm to protect against a lethal intranasal or intravaginal HSV infection. Also, stress decreases the ability of these CTLm to limit virus levels at the mucosal site of infection but does not have a significant effect on the levels of virus in the innervating sensory ganglia. Finally, stress decreases protection against HSV-mediated pathology of the vaginal epithelium. These studies are the first to examine the effects of stress on CTLm activation and function in vivo.

Immunostimulating complexes (ISCOMs) for nasal vaccination

The immunostimulating complex (ISCOM) is documented as a strong adjuvant and delivery system for parenteral immunization. Its effectiveness for mucosal immunization has also been proven with various incorporated antigens. Lövgren et al. were the first to demonstrate the capacity of influenza virus ISCOMs to induce mucosal immune response and protection after one comparatively low nasal dose. Further studies show that similar to Cholera toxin (CT) and Escherichia coli heat-labile toxin (LT), ISCOMs break immunological tolerance and exert strong mucosal adjuvant activity, resulting in secretory IgA and systemic immune responses. Striking is the capacity of ISCOMs to induce CTL response also after nasal administration. In contrast to CT, ISCOMs initiate mucosal as well as systemic immune responses in an IL-12 dependent manner but independently of IL-4. The recombinant B subunit of cholera toxin (rCTB) was incorporated in the same ISCOM particle to explore symbiotic effects. The IgA response to rCTB in lungs was increased 100-fold when rCTB was administered nasally in ISCOMs and more than 10-fold in the remote mucosa of the genital tract. An enhanced IgA response to a passenger antigen OVA was recorded in the remote genital tract. After i.n. administration of the envelope proteins of respiratory syncytial virus in ISCOMs, high serum antibodies were induced, almost at the same levels as those following parenteral immunization and potent IgA responses were also evoked both at the local respiratory mucosa, and in the cases tested at the distant mucosae of the genital and intestinal tracts. Similar results have also been recorded with ISCOMs containing envelope proteins from Herpes simplex virus, Influenza virus and Mycoplasma mycoides. The mucosal targeting property of envelope proteins of RSV was utilized in an HIV-gp120 RSV ISCOM formulation. After nasal administration an enhanced mucosal IgA response to gp120 was observed in the female reproductive tract. In general, antigens derived from envelope viruses or cell membranes incorporated into ISCOMs retain their biological activity and conformation, encompassing the mucosal targeting and virus neutralizing properties.

Intranasal immunization with CpG oligodeoxynucleotides as an adjuvant dramatically increases IgA and protection against herpes simplex virus-2 in the genital tract

Development of vaccines capable of preventing the transmission or limiting the severity of sexually transmitted viruses, such as HSV and HIV, will likely be dependent on the induction of potent long-lasting mucosal immune responses in the genital tract. Recently, synthetic oligodeoxynucleotides (ODN) containing immunostimulatory CpG motifs were shown to serve as potent adjuvants for the induction of mucosal immune responses. Here, we show that intranasal immunization with CpG ODN, plus recombinant glycoprotein B (rgB) of HSV-1, results in significantly elevated levels of specific anti-gB IgA Abs in vaginal washes that remained high throughout the estrous cycle. Additionally, dramatically elevated numbers of specific IgA Ab-secreting cells were present and persisted in the genital tract in response to intravaginal (IVAG) HSV-2 challenge. HSV-2-specific CTL were observed at moderate levels in the spleens of CpG or non-CpG ODN-immunized mice. In contrast, strong CTL responses were observed locally in the genital tissues of both groups following IVAG HSV-2 challenge. Interestingly, mice immunized intranasally with rgB plus CpG ODN, but not non-CpG ODN, were significantly protected following IVAG HSV-2 challenge. Measurement of virus in protected CpG-immunized mice revealed a log lower level of replication within the first few days after infection. In conclusion, these results indicate that intranasal immunization with CpG ODN plus protein mediates immunity in the female genital tract capable of protecting against a sexually transmitted pathogen.

Immunological memory in B-cell-deficient mice conveys long-lasting protection against genital tract infection with Chlamydia trachomatis by rapid recruitment of T cells

The role of antibodies and antigen deposition for the development of immunological memory has been incompletely investigated. We addressed whether long-term protection and T-cell memory can be stimulated against a genital tract infection with human Chlamydia trachomatis serovar D in B-cell-deficient (muMT) mice. At 6 months following a primary infection with C. trachomatis, both muMT and wild-type (WT) mice exhibited strong and comparable protection against reinfection. Evidence of long-lasting CD4+ T-cell memory was found in both muMT and WT mice, typified by comparable delayed-type hypersensitivity (DTH) reactions against chlamydial antigens. No bacterial or chlamydial DNA was found in the genital tract of muMT memory mice, suggesting that immunological memory was maintained in the absence of antigen. Whereas few T cells were present in the genital tract of memory mice, rapid recruitment of CD4+, and some CD8+, T cells into the genital tract tissue was observed after challenge with live bacteria. Accumulation of T cells in the genital tract was preceded by a short transient infection of similar magnitude in both muMT and WT memory mice, arguing against a long-term protective role of local antibodies. The rapid recruitment of CD4+ T cells into the genital tract was associated with a transient detection of interferon-gamma (IFN-gamma) mRNA in the genital tract in chlamydia-immune memory mice, which was not found in naïve, challenged mice. Thus, long-term protection in the genital tract against C. trachomatis infection is conveyed by IFN-gamma-producing CD4+ memory T cells, which appear to be maintained in the absence of antibodies and local antigen deposition.

Recent advances in mucosal vaccine development

Proper stimulation of the mucosal immune system is critical for the effective protection of mucosal surfaces against colonization and invasion of infectious agents. This requires administration of vaccine antigens directly to various mucosal sites. Due to the low absorption efficiency of mucosally delivered vaccines, however, almost all of the currently marketed vaccines are administered parentally. In addition, sub-optimal immune responses are frequently induced by mucosal immunization and the use of mucosal adjuvants is commonly required. As a result, development of successful mucosal vaccines depends largely on the improvement of mucosal antigen delivery and on the discovery of new and effective mucosal adjuvants. In this review, recent advances in both areas are briefly discussed.

Capture ELISA systems for the detection of bovine coronavirus-specific IgA and IgM antibodies in milk and serum

Isotype-capture ELISAs for BCV-specific IgA and IgM were developed and tested on milk and serum samples from Swedish cattle. The capture ELISAs showed higher sensitivity than indirect ELISAs for detection of BCV-specific IgA and IgM. In the capture ELISAs the agreement between detection in milk and serum samples was 94% for IgA and 86% for IgM. The correlation between log(10) titres in milk and serum was r=0.82 (P<0.001) for IgA and 0.84 (P<0.001) for IgM. Milk seemed a better target than serum for diagnosing specific IgA at low levels. There was no variation in the isotype-specific BCV antibody titres between healthy quarters of the same udder, but subclinical mastitis was associated with higher levels of IgA antibodies and weak false IgM positive reactions in undiluted milk. Bovine IgA and IgM antibodies in milk and serum showed high stability towards freezing and thawing and storage at room temperature. The antibody responses to BCV were followed in milk and serum from six dairy cows and in serum from four calves for a period of 1 year after an outbreak of winter dysentery (WD). In this outbreak some animals became reinfected with BCV. The IgA and IgM capture ELISAs differentiated between primarily BCV infected and reinfected animals. In the primarily infected cattle, IgM antibodies were first detected in milk and serum four to nine days after the first WD symptoms observed, and were subsequently detected for at least 2-3 weeks. IgM was also detected in the reinfected cows, but mostly at lower levels and for a shorter period of time than in the primarily infected animals. In milk, however, the IgM response of the reinfected cows was detected for a longer period of time than in serum. Six months after the outbreak, IgA was still detected in both serum and milk of all six cows and also in serum of one calf. The reinfected cows showed higher and more long-lasting peak levels of IgA in milk and serum than the primarily infected cows, indicating boosting of the IgA response.

Iscom and iscom-matrix enhance by intranasal route the IgA responses to OVA and rCTB in local and remote mucosal secretions

Iscoms, with rCTB incorporated via the GM1 receptor, enhanced in mice the mucosal immunogenicity of rCTB as antigen after intranasal (i.n.) administration both by inducing IgA response in the remote intestinal tract mucosa and by a 100-fold increase of the specific IgA locally in the lungs. Iscom-matrix as a separate entity mixed with rCTB enhanced the rCTB-IgA response similarly. While OVA in iscoms induced high mucosal IgA responses, iscom-matrix co-administered with OVA induced low or no mucosal IgA response to OVA. A synergism between iscoms and rCTB could only be seen as an adjuvant targeting effect enhancing the IgA response to OVA in the remote genital tract mucosa. In serum, the immunomodulatory effect of iscoms after i.n. administration was seen as an enhanced serum IgG2a response.

Entry sites for oral vaccines and drugs: A role for M cells, enterocytes and dendritic cells?

M cells have long been considered as the unique entry site of macromolecules and pathogens in the intestine, allowing delivery to antigen-presenting cells in the Peyer's patches. Therefore, antigen formulation for the development of oral vaccines has been based on administration of antigens in the form of live replicating pathogens or soluble antigen vectorized into biodegradable microspheres. However, progress in the understanding of the biology of dendritic cells, as well as identification of their localization at different sites of the intestine, suggest that they may capture antigen directly from the lumen of mucosal tissues or from epithelial cells of the intestine. Besides, a role for the absorptive epithelium in antigen presentation through both classical or non-classical MHC elements suggests that PP may not be the exclusive inductive site of the immune response in the gut. Thus, depending on the nature of the antigen (soluble or infectious) there may be different sites of antigen entry through the intestine, and each site may have distinct efficiency to promote a protective immune response, depending on the presence and function of dendritic cells. Cross talk between M cells, epithelial cells and dendritic cells may play an important role in determining the outcome of tolerance versus immunity.

Cytokine and immunoglobulin concentrations in cervical secretions: reproducibility of the Weck-cel collection instrument and correlates of immune measures

Elucidation of local immune response at the cervix is important for understanding and evaluating STD vaccine approaches currently being proposed. However, no well-validated method exists for the collection of cervical secretions for evaluation of cervical immune response. The purpose of this study was to determine the reproducibility of the Weck-cel sponge used to collect cervical secretions for immunological assessment. Additionally, it was possible to examine correlates of immunity as part of our investigation. Two cervical secretion specimens were collected sequentially from each of 120 women using Weck-cel sponges. Cervical secretions were collected prior to Pap smear sampling to avoid blood contamination. At the laboratory, the duplicate specimens were weighed and tested in replicate wells to determine the concentration of two cytokines (IL-10 and IL-12) and two immunoglobulin isotypes (IgG and IgA). IL-12, total IgG, and total IgA showed a strong correlation between samples from the same woman ranging from 0.78 to 0.84. Kappa coefficients obtained after categorizing assay results ranged from 0.62 to 0.67. Variance components analysis suggested that 69% to 85% of the variance observed was accounted for by between-women variance, with the remaining variability attributed to variation between samples collected from the same woman. IL-10 results were less reproducible than those obtained from the other assays examined, suggesting problems with the assay used to measure this cytokine rather than with the Weck-cel sampling instrument. Various factors were found to significantly correlate with cytokine and immunoglobulin measures at the cervix. Age and reproductive status were associated with all four immune measures; women over 50 years of age and those who were postmenopausal had increased concentrations of IL-10, IL-12, IgG, and IgA. Hemoglobin concentrations were positively correlated with IgG and IL-10 concentrations, but not with IgA or IL-12 concentrations, suggesting local production of IgA and IL-12. The concentration of all immune measures decreased with increasing volume of collection. No significant association was observed between time from collection to freezing of specimens and concentrations of cytokines or immunoglobulins. Overall, our data suggest that measurement of immunological parameters in cervical secretions collected using Weck-cel sponges are reproducible. In addition, various correlates of cytokine and immunoglobulin concentrations were identified.

The potential use of sperm antigens as targets for immunocontraception; past, present and future

Immunocontraception, and in particular the targeting of antibodies to gamete-specific antigens implicated in sperm egg binding and fertilisation, offers an attractive approach to the growing global problem of overpopulation. Such an idea is not new; indeed several immunocontraception trials, using animal model systems, have been reported in recent years and a number are reviewed here. However, the results of these studies have been largely disappointing. We believe that two fundamental flaws attribute to the poor success of most of these preliminary immunocontraceptive trials. Firstly, loss of fertility has invariably been used as the assay. This presupposes that immuno-neutralisation of a single, gamete-specific antigen will be sufficient to cause a significant reduction in fertility; however, recent data suggests that such a premise may not be well-founded for a number of reasons. Secondly, and arguably the most important flaw, is the almost universal, but largely inappropriate, use of systemic immunisation as the sole route of antigen delivery. Whilst systemic immunisation regimes may lead to high serum IgG levels, these levels do not correlate with specific antibody levels in the reproductive tract or with contraceptive efficacy. Hence, an alternative antigen delivery approach is required which will induce an effective local immune response in the reproductive tract. Here we discuss the ways in which this might be achieved.

The immunostimulating complex (ISCOM) is an efficient mucosal delivery system for respiratory syncytial virus (RSV) envelope antigens inducing high local and systemic antibody responses

ISCOM is an efficient mucosal delivery system for RSV envelope proteins as measured by antibody responses in respiratory tract secretions and in sera of mice following two intranasal (i.n.) administrations. Intranasally administered RSV ISCOMs induced high levels of IgA antibodies both in the upper respiratory tract and in the lungs. In the lungs, a prominent and long-lasting IgA response was recorded, which still persisted 22 weeks after the second i.n. immunization when the experiment ended. Subcutaneous (s.c.) immunization only induced low IgA titres in the upper respiratory tract and no measurable response to RSV was found in the lungs. Differences were also noticed in serum between the i.n. and s.c. modes of immunization. ISCOMs given intranasally induced earlier, higher and longer lasting IgM and IgG1 serum anti-RSV antibody responses than those induced by the s.c. mode of administration. A low serum IgE response was only detectable at 2 weeks after i.n. immunization with ISCOMs and after s.c. immunization with an inactivated virus, but no IgE response was detectable after s.c. injection of ISCOMs. The serum IgA response was more pronounced following s.c. injection of inactivated virus than after i.n. application of ISCOMs, and a clear-cut booster effect was obtained with a second immunization. Virtually no serum IgA response was detected after the s.c. administration of ISCOMs. In conclusion, the high immune responses induced by RSV ISCOMs in the respiratory tract and serum after i.n. administration indicate prominent mucosal delivery and adjuvant properties of the ISCOMs, warranting further studies.