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For a CD8 epitope-based vaccine to match different geographic locations, the targeted epitopes for cytotoxic T-lymphocytes (CTLs) must be present in the local circulating HIV-1 strains. Secondly, the vaccine epitopes should match the host population HLA types. We characterized two new HIV-1 isolates from Guinea-Bissau. Also, we have identified 15 subdominant CD8 epitopes representing common HLA super-types theoretically covering most HLA alleles in any population. Herein we demonstrate that the selected vaccine epitopes are well conserved and simultaneously present in sequences from West Africa and Denmark. Use of the selected epitopes will likely ensure ≥10 immune targets in the majority of candidates for experimental therapeutic vaccination in both geographic regions. Our results warrant testing of the selected vaccine epitopes in both geographic locations.

Genital human papillomavirus infection (HPV) is common and usually harmless. However, chronic cervical infection with high-risk HPV types can cause cell changes that may eventually lead to cancer. To determine the frequency of individual HPV types among mixed infections, we examined the type distribution among cervical specimens from more than 1000 Danish women. We also examined the HPV type distribution and the frequency of single and multiple HPV types for specimens from 113 women who underwent conization and were diagnosed with cervical intraepithelial neoplasia grade II or worse (CIN2+). Using microarray technology, we found that 49% of the HPV-positive patients were infected with multiple HPV types. Among the CIN2+ diagnosed women, this frequency was 41%. The most frequently found high-risk HPV type was HPV-16, which was found in 25% of the HPV-positive cervical specimens. Among the HPV positive CIN2+ diagnosed women, 48% were HPV-16 positive. Women younger than 30 years of age had a higher frequency of multiple infections (61%) than women older than 30 years (39%). We conclude that cervical infection with multiple HPV types is common among women in all age groups and among women with or without the diagnosis of CIN2+.

Recent human immunodeficiency virus type 1 (HIV-1) vaccination strategies aim at targeting a broad range of cytotoxic T lymphocyte (CTL) epitopes from different HIV-1 proteins by immunization with multiple CTL epitopes simultaneously. However, this may establish an immune hierarchical response, where the immune system responds to only a small number of the epitopes administered. To evaluate the feasibility of such vaccine strategies, we used the human leukocyte antigen (HLA)-A*0201 transgenic (tg) HHD murine in vivo model and immunized with dendritic cells pulsed with seven HIV-1-derived HLA-A*0201 binding CTL epitopes. The seven peptides were simultaneously presented on the same dendritic cell (DC) or on separate DCs before immunization to one or different lymphoid compartments. Data from this study showed that the T-cell response, as measured by cytolytic activity and gamma-interferon (IFN-gamma)-producing CD8(+) T cells, mainly focused on two of seven administered epitopes. The magnitude of individual T-cell responses induced by immunization with multiple peptides correlated with their individual immunogenicity that depended on major histocompatibility class I binding and was not influenced by mode of loading or mode of immunization. These findings may have implications for the design of vaccines based on DCs when using multiple epitopes simultaneously.

Cytotoxic T-lymphocytes (CTL) are critical for immune control of infection with human immunodeficiency virus type-1 (HIV-1) and searches for relevant CTL epitopes for immune therapy are ongoing. Recently, we identified 28 HLA-A2-binding HIV-1 CTL epitopes (1). In this follow-up study we fully genome sequenced HIV-1 from 11 HLA-A2(+) patients to examine the sequence variation of these natural epitopes and compared them with the patient's CD8(+) T-cell recall response. Often the epitope was conserved but only a few patients showed a CD8(+) T-cell recall response. This infrequent targeting may be explained by immune subdominance. CD8(+) T-cell recall response to a natural epitope could be measured despite sequence differences in the patient's virus. T-cell cross-reaction between such variants could be demonstrated in HLA-A2 transgenic mice. Nine infrequently targeted but conserved or cross-reacting epitopes were identified in seven HIV-1 proteins. More immunogenic anchor amino acid optimized immunogens were designed that induced T-cell cross-reaction with these natural epitopes. It is concluded that most of the new CTL epitopes are conserved but subdominant during the infection. It is suggested that T-cell promiscuity may explain the observed CD8(+) T-cell reaction to epitope variants and it may be possible to use the selected immune optimized epitope peptides for therapeutic vaccination.

In a rat model of chronic Pseudomonas aeruginosa lung infection mimicking cystic fibrosis, we investigated the possibility of preventing chronic lung inflammation or decreasing the progression of the infection. We compared the lethality, pathology, bacterial clearance, and immunogenicity after stimulation of the non-specific defence mechanisms by Escherichia coli lipopolysaccharide (LPS) or P. aeruginosa sonicate, or the acquired specific immune response by vaccination with the same bacterial antigens. One day prior to challenge with P. aeruginosa embedded in alginate beads, rats were stimulated with either E. coli LPS or P. aeruginosa sonicate. Four and two weeks prior to challenge other rats were vaccinated with either E. coli LPS or P. aeruginosa sonicate. Controls did not receive any stimulation or vaccination. The lethality after challenge was lower in rats stimulated with E. coli LPS (p= 0.02) or vaccinated with P. aeruginosa sonicate (p=0.03) as compared to controls. The histopathology of the surviving rats showed an acute inflammation dominated by polymorphonuclear leukocytes (PMNs), but the offending bacteria were not completely eliminated in any group. The increased survival was probably due to earlier recruitment of PMNs most likely mediated by either cytokines and other chemotactic factors (stimulated group) or the immune response in concert with the complement cascade (vaccinated group). The results of the present and previous vaccination studies show that it is possible to improve survival but not to prevent the chronic P. aeruginosa lung infection and inflammation caused by alginate-embedded bacteria.

Lipopolysaccharide (LPS, endotoxin) is a major inducer of cytokines, such as interleukin 1 (IL1), IL6, IL8 and tumor necrosis factor (TNF). A convenient microtiter assay was developed to measure such activity. LPS coated onto a plastic surface was used to stimulate purified human mononuclear cells (MNC) in microtiter plates. Following stimulation the supernatants were assayed for presence of TNF by ELISA. Purified rough and smooth LPS from Pseudomonas aeruginosa gave a dose-dependent TNF release over a range of 0.1-1.0 microgram LPS/well. The assay was subsequently used to investigate the biological activity of anti-LPS antibodies and other LPS-specific serum components in sera from patients with cystic fibrosis (CF). As a group, sera from 10 CF patients chronically infected with P. aeruginosa did not affect the LPS-induced TNF release, while sera from normal controls inhibited this biological activity. When individual CF patients with or without chronic lung infection are considered, the antibodies appear to either enhance or inhibit the LPS-stimulated TNF release (range: 73-120%), while all antibodies from healthy controls inhibit the activity of LPS (range: 76-97%). Only a weak correlation (rho = 0.491, p = 0.037, n = 19) was found between the antibody titer in ELISA and the biological activity of sera. This new assay is suggested for convenient measurement of interference with cytokine induction from human MNC by patient or therapeutic anti-LPS antibodies and other LPS-specific serum components.

A human intravenous IgG preparation (Anti-LPS IgG) rich in antibodies to different lipopolysaccharides (LPS) and a normal human intravenous IgG (NIgG) were investigated for their ability to confer passive immunity. Both preparations were given at the time of infection (prophylaxis) or during sepsis (therapy) to burned mice with lethal infection induced by various clinically relevant gram-negative bacteria. When given at the time of infection both IgG preparations (5 mg/mouse) inhibited lethality induced by some bacteria (Pseudomonas aeruginosa serogroup G and B), but not others (Serratia marcescens, Klebsiella pneumonia, Proteus mirabilis), indicating a protection by by strain-specific antibodies. However, no significant protection was seen when mice were treated during sepsis. The range of specific antibody titers to the whole live bacteria and heat-killed (LPS-preserved) bacteria in the NIgG paralleled that of Anti-LPS IgG; however, the magnitude of the antibody titers did not accurately reflect the protective capacity in vivo. Thus, the exact specificity of the protective antibodies is still unknown. The protective effect of both IgG preparations was dose-dependent; at low IgG doses (0.5 mg/mouse) better protection was obtained with Anti-LPS IgG, whilst at higher doses (> or = 1 mg/mouse) both preparations exhibited identical effects. Low doses of either IgG preparation in combination with subtherapeutic doses of piperacillin significantly enhanced early survival (day 2 for NIgG and day 2 + 3 for Anti-LPS IgG) against P. aeruginosa, but the protective effect waned thereafter. We conclude that a strain-specific antibacterial effect in a compromised mouse infection model can be obtained by early passive immunization with human IgG from large plasma pools. It is suggested that Anti-LPS IgG or NIgG may be of benefit in some cases of gram-negative sepsis when administered as prophylaxis together with proper antibiotic treatment.

Micromethods were developed to extract lipopolysaccharide (LPS, endotoxin) from single bacterial colonies of the 20 recognized Pseudomonas aeruginosa type strains. The appearance of these LPSs in polyacrylamide gel electrophoresis (PAGE) and their reactivity with serum of cystic fibrosis (CF) patients chronically infected with P. aeruginosa was studied. Silver staining of LPS after PAGE showed that 13 of the P. aeruginosa LPSs had high numbers of O-repeating units arranged in 1-4 clusters of banding. Low-molecular-weight LPS fractions were more prominent in six of the serotype strains, of which O:7 and O:14 appeared semi-rough. Corresponding immunoblots using the CF sera showed LPS patterns very similar to the silver-stained appearance, indicating an immune reaction to all P. aeruginosa LPS including that from the newly discovered O:18, O:19 and O:20. This was unexpected since only a few serotype strains (mostly O:3, O:6 and O:9) had been isolated from the patients. Absorption experiments using purified and chemically defined P. aeruginosa rough LPS and smooth LPS suggested these immune reactions were due to antibodies cross-reactive to core/lipid A as well as to lower molecular weight O-polysaccharides or "A-bands". However, in some cases O:3, O:6, and O:9 LPSs were also found to contain additional distinct O-epitopes. Immune recognition of various polyagglutinable P. aeruginosa LPSs seemed also to be caused by cross-reactive antibodies. The described microextraction methods, followed by PAGE and silver staining or immunoblotting, are easy and convenient techniques with which to study antibodies against LPS epitopes and to screen for LPS phenotypic appearance using only a few bacterial colonies from larger numbers of Gram-negative bacterial strains.

Sputum samples from seven patients with cystic fibrosis and chronic P. aeruginosa lung infection were investigated for immune complexes by PEG precipitation and in two different complement binding assays. All seven patients were immune complex positive. The components involved in immune complex formation were identified by SDS-PAGE and immunoblotting. We found P. aeruginosa lipopolysaccharide as a major antigen. Both core and O-specific saccharide antigens could be demonstrated. IgG and IgA were the immunoglobulins involved, with IgG2 as the dominating IgG subclass. Lipopolysaccharide has a number of biological activities and its presence in sputum may have consequences for the pathogenesis of lung disease in cystic fibrosis.

Human mononuclear cells (MNC) were stimulated in culture with LPS to produce tumour necrosis factor (TNF). The natural tumour necrosis factor (nTNF) was quantitated by ELISA and immunoblotting using rabbit antibodies to human recombinant TNF (rTNF) and the biotin-avidin-peroxidase system. Biologically active nTNF was determined by its cytotoxic activity for actinomycin-D treated mouse fibroblasts and by its lethal effect in D-galactosamine sensitized endotoxin-resistant mice. Two different LPS preparations (Salmonella abortus equi and Pseudomonas aeruginosa) induced the formation of comparable amounts of nTNF. MNC from different donors, however, showed large variations in their ability to produce nTNF. The amount of nTNF induced in response to LPS could be enhanced by priming the MNC with interferon. The amounts of nTNF determined by ELISA generally correlated well with the activity of the nTNF in the two biological assays. On a weight basis, the lethal activity of nTNF in D-galactosamine treated mice was very similar to that of human rTNF. Immunoblotting revealed a single band of nTNF with the same molecular weight (17 kD) as human rTNF. The lethality induced by nTNF was inhibited by rabbit anti-human rTNF antibodies.