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Background: The P2-VP8 subunit vaccine for the prevention of rotavirus gastroenteritis is comprised of a truncated VP8 subunit protein from the rotavirus Wa strain (G1[P8]) fused to the tetanus toxin P2 epitope, and adsorbed on aluminum hydroxide for intramuscular administration., Methods: Three groups of 16 adults were randomized to receive three injections of P2-VP8 (12) or placebo (4) at doses of 10, 30 or 60 μg of vaccine. IgG and IgA antibodies to P2-VP8 were assessed by ELISA in serum and lymphocyte supernatant (ALS). Serum samples were tested for neutralizing antibodies to homologous and heterologous strains of rotavirus., Results: The vaccine was well-tolerated. All vaccine recipients demonstrated significant IgA responses and all but one demonstrated IgG responses; in the 60 μg cohort, geometric mean titers (GMTs) rose 70- and 80-fold for IgA and IgG, respectively. Homologous neutralizing antibody responses were observed in about half of participants in all three dose cohorts; in the 60 μg cohort, GMTs against Wa rose from 128 to 992. Neutralizing antibody responses were robust to P[8] strains, moderate to P[4] strains and negligible to P[6] strains. ALS IgA responses were dose dependent., Conclusions: The P2-VP8 subunit vaccine was well tolerated and evoked promising immune responses., Clinical Trials Registration: NCT01764256., (Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The 2009 influenza A/H1N1 pandemic demonstrated that a pandemic influenza virus has the potential to spread more rapidly in today's highly interconnected world than in the past. While pandemic morbidity and mortality are likely to be greatest in low-resource countries, manufacturing capacity and access to influenza vaccines predominantly exist in countries with greater resources and infrastructure. Even with recently expanded manufacturing capacity, the number of doses available within a 6-month timeframe would be inadequate to fully immunize the global population if the decision to implement a global vaccination program were made today. Improved, affordable vaccines are needed to limit the consequences of a global influenza outbreak and protect low-resource populations. PATH's Influenza Vaccine Project is supporting a range of activities in collaboration with private- and public-sector partners to advance the development of promising influenza vaccines that can be accessible and affordable for people in low-resource countries.

The current recommended infant vaccination schedules require many injections at multiple sites, which increase stress for infants and parents and may create challenges to vaccination compliance. Therefore, combination vaccines, which reduce the number of injections at each medical visit, can be an essential method to improve compliance. The objective of this study was to assess the safety and immunogenicity of an investigational, liquid, hexavalent, pediatric vaccine at 2, 4, 6, and 12-14 months of age. In this multicenter, open-label controlled study, 756 infants were randomized in approximately equal numbers to receive 0.5mL intramuscular dose of diptheria-tetanus-pertussis-polio-Haemophilus influenzae type b+hepatitis B vaccine, or 1 of 3 double-blind investigational formulations. All formulations included a hepatitis B surface antigen (HBsAg) concentration of 10μg/0.5mL. The three hexavalent vaccine formulations used in this study contained either Hib polyribosylribitol phosphate (PRP) conjugate component (tetanus toxoid [PRP-T, 12μg] or Neisseria meningitidis outer membrane protein complex [PRP-OPMC, 3μg or 6μg]): a minimum acceptable postdose 3 antibody response rate for each antigen was defined by the lower limit of a 95% confidence interval exceeding a prespecified target. Rates of adverse events (AEs) were similar among groups, with a trend for increased solicited vaccine-related injection-site reactions (pain, erythema, swelling) with increasing PRP-OMPC dose. No serious vaccine-related AEs were reported in the investigational groups. Both PRP-OMPC formulations met prespecified acceptability criteria for all antigens: PRP, HBsAg, pertussis, diphtheria, tetanus and poliovirus. The PRP-T formulation met the acceptability criterion for antibody responses to all antigens other than PRP at postdose 3. Postdose 4 responses were adequate for all antigens in all formulations. All vaccine formulations were well-tolerated. Both PRP-OMPC formulations met prespecified immunogenicity criteria of PRP-OMPC evaluation., (Copyright © 2010 Elsevier Ltd. All rights reserved.)

Combination vaccines improve parental and provider satisfaction and schedule compliance by decreasing the number of injections. In a Phase 2, randomized, double-blind, multicenter study, we compared four formulations of a liquid, hexavalent diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae b conjugate-hepatitis B virus (DTaP-IPV-Hib-HBV) vaccine in 708 infants immunized at 2, 3, 4, and 12-14 months of age. The formulations contained identical DTaP and IPV components, differing in the contents of Hib polyribosylribitol phosphate (PRP) conjugate component (tetanus-toxoid [PRP-T, 12microg] or Neisseria meningitidis outer-membrane-protein-complex [PRP-OMPC, 3microg or 6microg]), and in hepatitis B surface antigen (HBsAg, 10microg or 15microg). A minimum acceptable postdose 3 antibody response rate was defined by the lower limit of the 95% confidence interval exceeding a prespecified target. Rates of adverse events (AEs) were similar among groups, with a trend for increased solicited injection-site reactions (pain, redness, swelling) with increasing PRP-OMPC and HBsAg concentration. Serious AEs reported by eight subjects were not considered to be vaccine related. All PRP-OMPC formulations met prespecified acceptability criteria for postdose 3 immunogenicity for all antigens: PRP, HBsAg, pertussis, diphtheria, tetanus and polio. Apart from the Hib response, the postdose 3 responses obtained with the PRP-T formulation met the acceptability criterion for each antigen. Postdose 4 responses were acceptable for all antigens in all formulations. All vaccine formulations were well tolerated. The three PRP-OMPC formulations met prespecified immunogenicity criteria, and the one with the lowest PRP-OMPC concentration was selected for further optimization of immunogenicity.

Background: Merck has developed a manufacturing process modification for RECOMBIVAX HB. Three lots of modified process hepatitis B vaccine (mpHBV) were studied in a randomized, blinded trial to demonstrate similarity of the three lots of mpHBV and noninferiority to RECOMBIVAX HB (control vaccine) with regard to immunogenicity., Results: Month 7 SPRs for the mpHBV groups ranged from 97.8 to 98.9% (98.2% for the mpHBV groups combined). The seroprotection rate (SPR) for the control group was 98.5%. The estimated geometric mean titer (GMT) was 1761 mIU/mL for the mpHBV groups combined and 1108 mIU/mL for the control group. The GMT ratio (mpHBV/control) was 1.6 [95% confidence interval (CI): 1.2 to 2.1], indicating superiority of mpHBV compared with control. The percentages of subjects reporting any adverse experience (AE), injection-site AEs, or systemic AEs were similar across the four vaccination groups. There were no serious AEs., Methods: Healthy 20-to 35-year-old subjects (N = 860) received a 1-mL intramuscular dose [10 mcg hepatitis B surface antigen (HBsAg)] of mpHBV from 1 of 3 lots or control at Day 1, and Months 1 and 6. Serum antibody to HBsAg (anti-HBs) was assayed Predose 1 and 1 month Postdose 3 (Month 7) using a quantitative hepatitis B antibody assay (Ortho VITROS ECi assay). Anti-HBs GMTs and SPRs (% of subjects with an anti-HBs titer > or =10 mIU/mL) were compared at Month 7. After each dose, injection-site AEs and oral temperature were recorded for 5 days; systemic AEs were recorded for 15 days., Conclusions: The SPRs for the mpHBV groups and the control group were high; responses were consistent across the mpHBV groups. The mpHBV and control vaccines were generally well tolerated.

The global need for a pandemic influenza vaccine is large. High-income countries have stated their intent to provide universal access for pandemic influenza vaccine to their populations. Assuming that a two-dose schedule would be needed, providing universal coverage globally would represent approximately 6.5 billion two-dose courses or 13 billion doses. In the best case scenario, should an outbreak of pandemic influenza occur in the near term, using H5N1 as a proxy for the pandemic virus, the total available doses for the global population within six months of an out break would be only 1.2 billion courses or 2.4 billion doses. In addition, current stockpiles of pandemic influenza vaccine are limited. However, promising developments are occurring with respect to global capacity, technological innovation, and global conviction that offer potential solutions to the problem of pandemic influenza vaccine supply for the world's population.

Background: Premature infants seem to be at greater risk of hospitalization from rotavirus gastroenteritis than term infants. Safety and efficacy of the pentavalent human-bovine (WC3) reassortant rotavirus vaccine were assessed in premature infants enrolled in the large-scale, blinded, placebo-controlled rotavirus efficacy and safety trial (REST)., Methods: Healthy infants 6-12 weeks of chronologic age at study entry were randomized to receive 3 oral doses of pentavalent rotavirus vaccine or placebo at 4- to 10-week intervals. Infants born at < or =36 weeks of gestational age were eligible if thriving at the time of enrollment. Safety and efficacy were retrospectively assessed in these premature infants comparing vaccine with placebo recipients. Cases of rotavirus gastroenteritis were defined as forceful vomiting and/or > or =3 watery or looser-than-normal stools within a 24-hour period, accompanied by detection of rotavirus antigen in the stool., Results: A total of 2070 infants between 25 and 36 gestational weeks received at least 1 dose of vaccine or placebo; 1005 vaccine recipients and 1061 placebo recipients were evaluable for safety. Serious adverse events occurred in 55 vaccine recipients (5.5%) and 62 placebo recipients (5.8%). In a nested substudy of 308 premature infants evaluable for detailed safety (154 in each group), the frequencies of fever, diarrhea, vomiting, and irritability were comparable between vaccine and placebo recipients. Overall, 3 doses of the pentavalent vaccine reduced the rate of hospitalizations and emergency department visits in premature infants due to rotavirus gastroenteritis by 100% (95% CI: 82.2-100) compared with placebo. The vaccine also prevented 73.0% (95% CI: -2.2-95.2) of rotavirus gastroenteritis cases of any severity., Conclusions: In this post hoc analysis of healthy premature infants, the pentavalent rotavirus vaccine was generally well-tolerated and substantially reduced rotavirus-attributable hospitalizations and emergency department visits compared with placebo. Overall, vaccine safety and efficacy seemed to be generally comparable to the results in the REST study population as a whole. These results support vaccinating healthy premature infants on the same schedule as term infants.

Background: A live pentavalent rotavirus vaccine (PRV) containing 5 human-bovine (WC3) reassortants expressing human serotypes G1, G2, G3, G4 and P1A[8] was evaluated in a blinded, placebo-controlled study. Possible interactions between PRV and concomitantly administered licensed pediatric vaccines were investigated in a United States-based nested substudy (Concomitant Use Study) of the Rotavirus Efficacy and Safety Trial., Methods: From 2002 to 2003, healthy infants approximately 6 to 12 weeks of age at entry were randomized to receive either 3 oral doses of PRV or placebo at 4- to 10-week intervals. Subjects were also to receive combined Haemophilus influenzae type b and hepatitis B vaccine (2 doses), diphtheria and tetanus toxoids and acellular pertussis vaccine (3 doses), inactivated poliovirus vaccine (2 doses) and pneumococcal conjugate vaccine (3 doses) on the same day; oral poliovirus vaccine was not administered. Immunogenicity was assessed by measuring antibody responses to PRV and antigens contained in the licensed vaccines. Cases of rotavirus gastroenteritis were defined by forceful vomiting and/or -3 watery or looser-than-normal stools within a 24-hour period, and detection of rotavirus antigen in the stool. Safety was assessed by reporting of adverse events using diary cards., Results: The Concomitant Use Study enrolled 662 subjects in the PRV group and 696 subjects in the placebo group. For the 17 antigens in the concomitantly administered vaccines, antibody responses were similar in PRV and placebo recipients, except for moderately diminished antibody responses to the pertactin component of pertussis vaccine. Efficacy of PRV against rotavirus gastroenteritis of any severity was 89.5% (95% CI = 26.5-99.8%). PRV was generally well tolerated when given concomitantly with the prespecified vaccines., Conclusions: In this study, antibody responses to the concomitantly administered vaccines were generally similar in PRV and placebo recipients. PRV was efficacious and well tolerated when given concomitantly with pediatric vaccines licensed in the United States.

Background: Rotavirus is the leading cause of dehydrating acute gastroenteritis in infants worldwide. Previous studies of a live pentavalent human-bovine reassortant rotavirus vaccine have shown it to be efficacious across a range of potencies., Objective: Our goal was to evaluate the efficacy, immunogenicity, and safety of pentavalent rotavirus vaccine at the end of shelf life in healthy infants., Patients and Methods: During 2002-2004, 1312 healthy infants approximately 6 to 12 weeks old from the United States (47%) and Finland (53%) were randomly assigned to receive 3 oral doses of vaccine (vaccine at approximately 1.1 x 10(7) infectious U per dose) or placebo approximately 4 to 10 weeks apart. Infants were to be followed for acute gastroenteritis through 1 rotavirus season after vaccination and for adverse events postvaccination., Results: Three doses of pentavalent rotavirus vaccine at the end of shelf life demonstrated efficacy against rotavirus gastroenteritis caused by human G-serotypes included in the vaccine (G1-G4). Efficacy against severe rotavirus gastroenteritis was 100%, and efficacy against any rotavirus gastroenteritis regardless of severity was 72.5%. A threefold rise in G1 serum neutralizing was observed in 57% and in anti-rotavirus immunoglobulin A in 96% of pentavalent rotavirus vaccine recipients. No statistically significant increase in vomiting, diarrhea, or irritability was observed among pentavalent rotavirus vaccine recipients compared with placebo recipients within the 7-day period from each dose. A statistically significant increase in fevers (> or = 100.5 degrees F, rectal equivalent) was observed among pentavalent rotavirus vaccine recipients compared with placebo recipients after dose 1., Conclusions: This pentavalent human-bovine rotavirus vaccine was generally well tolerated, efficacious, and immunogenic at the end of shelf life.

Background: Rotavirus is a leading cause of childhood gastroenteritis and death worldwide., Methods: We studied healthy infants approximately 6 to 12 weeks old who were randomly assigned to receive three oral doses of live pentavalent human-bovine (WC3 strain) reassortant rotavirus vaccine containing human serotypes G1, G2, G3, G4, and P[8] or placebo at 4-to-10-week intervals in a blinded fashion. Active surveillance was used to identify subjects with serious adverse and other events., Results: The 34,035 infants in the vaccine group and 34,003 in the placebo group were monitored for serious adverse events. Intussusception occurred in 12 vaccine recipients and 15 placebo recipients within one year after the first dose including six vaccine recipients and five placebo recipients within 42 days after any dose (relative risk, 1.6; 95 percent confidence interval, 0.4 to 6.4). The vaccine reduced hospitalizations and emergency department visits related to G1-G4 rotavirus gastroenteritis occurring 14 or more days after the third dose by 94.5 percent (95 percent confidence interval, 91.2 to 96.6 percent). In a nested substudy, efficacy against any G1-G4 rotavirus gastroenteritis through the first full rotavirus season after vaccination was 74.0 percent (95 percent confidence interval, 66.8 to 79.9 percent); efficacy against severe gastroenteritis was 98.0 percent (95 percent confidence interval, 88.3 to 100 percent). The vaccine reduced clinic visits for G1-G4 rotavirus gastroenteritis by 86.0 percent (95 percent confidence interval, 73.9 to 92.5 percent)., Conclusions: This vaccine was efficacious in preventing rotavirus gastroenteritis, decreasing severe disease and health care contacts. The risk of intussusception was similar in vaccine and placebo recipients. (ClinicalTrials.gov number, NCT00090233.), (Copyright 2006 Massachusetts Medical Society.)

Background: In a previous clinical trial comparing COMVAX with its monovalent components, PedvaxHIB and RECOMBIVAX HB, one of 92 comparisons of post-vaccination adverse experiences revealed a higher rate of unusual, high-pitched crying following the second, but not the first or third doses of COMVAX compared with two monovalent control vaccines. Rates of prolonged crying were similar between groups at each visit., Objectives: To compare the frequencies of unusual, high-pitched crying between recipients of COMVAX plus placebo and recipients of PedvaxHIB plus RECOMBIVAX HB following the second vaccine doses (primary) and to summarize the frequency of unusual, high-pitched crying and prolonged crying after each vaccination visit., Design: We enrolled 1215 healthy infants in a randomized, double blind, placebo-controlled study. Participating infants received study vaccines at 2 and 4 months of age and other routine childhood vaccines at 6-7 weeks and 3 months of age. Crying was evaluated via questionnaire at the time of enrollment (baseline) and daily from days 0 to 2 after each injection., Results: Reports of unusual, high-pitched crying and prolonged crying were uncommon (<1%) prior to the first vaccination visit and were comparable in both treatment groups. After each injection, rates of unusual, high-pitched crying (range: 4.26-6.96%) and prolonged crying (range: 0-1.36%) appeared similar between treatment groups and for each vaccination visit. Crying resolved in all infants; no neurological impairment was reported., Conclusion: This study found no statistically significant differences in rates of unusual, high-pitched crying and prolonged crying in infants vaccinated with COMVAX plus placebo compared with infants vaccinated with its monovalent components, PedvaxHIB and RECOMBIVAX HB.

Background: Reinfection, a common occurrence with gonorrhea, may result from a lack of protective immune response, or from the tremendous gonococcal strain variation., Goal: A two-phase study in human volunteers tested whether experimental infection with Neisseria gonorrhoeae MS11mkC would protect against reinfection with the same organisms., Study Design: In phase 1, an intraurethral inoculum of 57,000 piliated, transparent (opacity protein-negative [Opa-]) MS11mkC N gonorrhoeae infected 14 of 15 (93%) volunteers. The volunteers were encouraged to delay treatment for at least 5 days. In phase 2, which began 2 weeks after treatment for the initial infection, volunteers were inoculated with 7,100 piliated, Opa- MS11mkC., Results: The phase 2 challenge infected 6 of 14 (43%) previously infected volunteers and 5 of 10 (50%) naïve control subjects. Phase 1 volunteers who resisted reinfection were significantly more likely to have had a fourfold or greater increase in lipooligosaccharide immunoglobulin G during phase 1 than those who did not resist reinfection (P = 0.026)., Conclusions: Although infection did not provide protection from reinfection under the conditions used, the results suggest that immunity to reinfection is more complex than anticipated by the experimental design.

The Northern Territory of Australia has had historically very high incidence rates of invasive Haemophilus influenzae type b disease in children less than 5 years of age, with the burden of disease greatest among Aboriginal infants less than 12 months. This study documents the impact of conjugate Hib vaccines introduced in 1993. Immunization rates were monitored using an existing immunization register, and case finding was done retrospectively using hospital and laboratory records. Following the vaccine introduction, the incidence fell abruptly to a seventh of its pre-vaccination level, in both Aboriginal and non-Aboriginal children. The effectiveness of PRP-OMPC (PedvaxHIB) was 97.5% and the overall effectiveness of the vaccination programme was 86.3%. The study shows Hib immunization as an effective intervention while discussing continuing needs for Hib control in high risk populations. It also illustrates the benefit of immunization registers in the evaluation of immunization programmes and assessment of vaccine effectiveness.

Inflammatory cytokine production in men was examined after intraurethral challenge of volunteers with Neisseria gonorrhoeae MS11mkA or MS11mkC. Increased interleukin (IL)-8, IL-6, and tumor necrosis factor-alpha (TNF-alpha) were detected in urine before the onset of symptoms and peaked simultaneously with the detection of IL-1 beta at the onset of symptoms. Urine cytokine levels returned to baseline or near baseline within 48 h after antibiotic therapy. In plasma, IL-8, TNF-alpha, IL-1 beta, and IL-6 were elevated at the onset of symptoms in 9, 5, 4, and 3 of 10 subjects, respectively, and returned to near normal within 48 h after treatment. IL-1 alpha and granulocyte-macrophage colony-stimulating factor were not consistently detected in urine or plasma after challenge. Cytokine mRNA transcripts in peripheral blood mononuclear cells were not altered by the infection. The findings suggest that IL-8, IL-6, and possibly TNF-alpha were produced at the local site of infection, whereas IL-1 beta was derived from infiltrating leukocytes.

Neisseria gonorrhoeae MS11mkA (mkA) expresses one 3.6-kDa lipooligosaccharide (LOS). Variant MS11mkC (mkC), expressing four larger LOSs, occurs in vitro among mkA at a frequency of 10(-3). Infectivity of these variants was compared in 2 groups of volunteers inoculated with approximately 40,000 piliated, Opa- gonococci of either strain. The mkC variant infected 5 of 5 while mkA infected only 2 (40%) of 5. Gonococci recovered from the mkA infections showed a transition toward the mkC LOS phenotype. The mkA inoculum contained approximately 40 mkC gonococci. These data confirmed earlier studies and suggested that small numbers of mkC gonococci would be infective. This hypothesis was tested in three more experiments. In two, volunteers were inoculated with 250 or 1250 mkC, infecting 3 of 7 in each group, and in the third, 1600 mkC infected 2 of 6, resulting in a total of 8 of 20 infected by < or = 1600 mkC. Gonococci shed by infected volunteers maintained the mkC LOS phenotype but shifted from Opa- to Opa+. Thus, LOS and opacity protein, as well as pilus, are gonococcal virulence factors.

The field of public health and medicine stands to benefit immensely from the emerging vaccine technologies and improved application of existing technologies. Technological advances may promote: (1) greater flexibility and simplicity in the design and operation of immunization campaigns or ongoing prevention programs, including reduction in number of vaccine doses, cold chain elimination, slow-release/prolonged antigenic stimulation, reduced cost and hazard and increased ease of administration through noninvasive, oral delivery systems, greater population levels of immunization and health; (2) the development of documents by FDA, WHO, and other regulatory authorities and groups, to assist the manufacturer in the appropriate manufacturing, preclinical, and clinical development of these new vaccines; (3) a greater array of vaccines to protect the civilian and military populations; (4) increased vaccine potency; (5) vaccines eliciting mucosal immunity, cytotoxic T cells, and/or neutralizing antibody. At the end of the 20th century there remain many unconquered pathogens and noninfectious indications for which medical science suggests that vaccines could be effective. New technologies may provide the best hope to address this wide array of public health needs.

Thai soldiers were vaccinated with a recombinant protein derived from the central repeat region of the circumsporozoite (CS) protein of Plasmodium falciparum conjugated to Toxin A (detoxified) of Pseudomonas aeruginosa (R32Tox-A) to evaluate its safety, immunogenicity and efficacy. In a randomized, double-blind manner, 199 volunteers received either R32Tox-A or a control vaccine at 0, 8 and 16 weeks. Immunization was performed in a malaria non-transmission area, after completion of which volunteers were deployed to an endemic border area and monitored closely to allow early detection and treatment of infection. The vaccine was found to be safe and to elicit antibody responses in all vaccinees. Peak CS antibody (IgG) concentrations in malaria-experienced vaccinees exceeded those in malaria-naive vaccinees (mean 40.6 versus 16.1 micrograms ml-1; p = 0.005) as well as those induced by previous CS protein-derived vaccines and observed in association with natural infections. A log-rank comparison of time to falciparum malaria revealed no differences between vaccinated and non-vaccinated subjects. Secondary analyses revealed that CS antibody levels were lower in vaccinee malaria cases than in non-cases, 3 and 5 months after the third dose of vaccine (p = 0.06 and p = 0.014, respectively). Because antibody levels had fallen substantially before peak malaria transmission occurred, the question of whether high levels of CS antibody are protective remains to be resolved.

The antibiotic susceptibilities of Neisseria gonorrhoeae isolates obtained from patients attending sexually transmitted disease clinics in Cholburi and Bangkok, Thailand, were determined by agar dilution. Some 28.2% of isolates produced beta-lactamase. A total of 97.9% of beta-lactamase-positive and 51% of beta-lactamase-negative isolates tested were resistant to penicillin (MICs, greater than or equal to 2 micrograms/ml), 70% of isolates tested were resistant to tetracycline (MICs, greater than or equal to 2 micrograms/ml), and 91% of isolates tested were susceptible to spectinomycin (MICs, less than or equal to 64 micrograms/ml). The MICs for 90% of isolates for the other drugs tested were 2 micrograms/ml for erythromycin, 2 micrograms/ml for cefoxitin, 1 micrograms/ml for cefuroxime, 0.125 micrograms/ml for cefpodoxime, 0.06 micrograms/ml for cefotaxime, 0.25 micrograms/ml for ceftazidime, 0.03 micrograms/ml for ceftizoxime, 0.03 micrograms/ml for ceftriaxone, 0.03 micrograms/ml for cefixime, 0.06 micrograms/ml for aztreonam, 0.008 micrograms/ml for ciprofloxacin, 0.125 micrograms/ml for norfloxacin, and 0.075 micrograms/ml for ofloxacin. Fewer than 1.5% of isolates were resistant to the extended-spectrum cephalosporins tested. Some 0.3% or fewer isolates were resistant to broad-spectrum cephalosporins, fluoroquinolones, or the monobactam aztreonam. Antibiotic resistance among N. gonorrhoeae isolates from Cholburi and Bangkok in May 1990 appeared to be primarily limited to penicillin and tetracycline, which are no longer used to control gonorrhea. Spectinomycin, which has been in general use against gonorrhea in Thailand since 1983, has dwindling utility, with resistance at a level of 8.9%.

To learn how lipooligosaccharide (LOS) phase variations affect pathogenesis, we studied two male volunteers who were challenged intraurethrally with Neisseria gonorrhoeae that make a single LOS of 3,600 daltons and sequentially followed LOS expression by gonococci as urethritis developed. LOS variation occurred in vivo. Signs and symptoms of gonorrhea began with the appearance of variants making 4,700-dalton LOS that are immunochemically similar to glycosphingolipids of human hematopoietic cells (Mandrell, R.E., J.M. Griffiss, and B.A. Macher. 1989. J. Exp. Med. 168:107) and that have acceptors for sialic acid. A variant that appeared at the onset of leukorrhoea was shed by 34/36 men with naturally acquired gonorrhea at the time they sought medical attention; the other two shed the variant associated with dysuria. None shed the challenge variant. These data show that in vivo phase shifts to higher molecular mass LOS that mimic human cell membrane glycolipids are associated with the development of gonococcal leukorrhea.

A randomized, placebo-controlled, double-blind efficacy trial of a purified gonococcal pilus vaccine composed of a single pilus type was tested in 3123 men and 127 women volunteers. Either 100 micrograms of vaccine or a placebo was given intradermally on day 1 and day 14. Each group was evenly matched with respect to age, sex, prior history of a sexually transmitted disease, sexual exposure during the study and attrition from the study. None of the women volunteers acquired gonorrhoea during the trial. In the male volunteers, 108 vaccine and 102 placebo recipients acquired gonorrhoea 15 days or later after the initial immunization. Vaccines developed a sustained ELISA antibody response to homologous and heterologous pili, but the latter titres were approximately 40% as high as the homologous pilus antibody rises. There were, however, no increases in inhibition of attachment antibody (IEA) titres. Local antibodies (semen) against homologous and heterologous strains were also elicited (ELISA). The vaccine was safe and did not alter the clinical expression of disease. This gonococcal pilus vaccine composed of a single pilus type failed to protect men against gonococcal urethritis.

In 1983, a gonococcal pilus vaccine failed to show protection in a large, placebo-controlled, double-blind field trial. The epitopic response to this vaccine was investigated in a random subgroup of 20 vaccine recipients. Using Western blot analysis of the immunizing pilus and its cyanogen bromide (CNBr) fragments, IgG antibody to pilin was detected before immunization in all individuals. Preexistent antibody to the CNBr-2 and CNBr-3 fragments of pilin was detected in 65% and 5% of individuals, respectively. Pilus immunization resulted in a vigorous response to the CNBr-2 fragment in 100% of the individuals tested; only 33% developed antibody to the CNBr-3 fragment. Absorptions of postimmunization sera with different gonococcal strains resulted in either complete or partial removal of antibody to the CNBr-2 fragment. In the context of an unsuccessful vaccine trial, these results suggest that antibody to the CNBr-2 fragment of pilin may not be protective.

A gonococcal pilus vaccine or placebo was injected subcutaneously or intramuscularly into 71 human volunteers. The vaccine was found to be safe. The principal adverse reaction was a complaint of a sore arm, which was caused, at least in part, to the volume of material injected. 6 of 64 (9%) volunteers receiving the larger doses also complained of malaise. The vaccine was found to be antigenic. All of the volunteers developed an immunoglobulin class-specific antibody response as measured by a solid phase radioimmunoassay. The antibody was capable of blocking the attachment of gonococci to epithelial cells. A slight antibody response was also demonstrated to gonococcal lipopolysaccharide but the antibody responsible for blocking attachment of gonococci was directed entirely at the pilus protein. The stimulated antibodies were shown to crossreact with isolated pili of heterologous gonococcal strains and to block the attachment of heterologous gonococci. Absorption of immune sera by a heterologous pilus reduced the inhibition of attachment antibodies to pre-immune level, suggesting that the immune response was directed at a common pilus determinant.

Bacterial pili (fimbriae) are protein appendages which extend from the cell surface and serve to adhere the microorganism to body surfaces. These appendages have been isolated, purified and characterized as vaccine candidates. These vaccines stimulate an immune response which serves at least with regards to Neisseria gonorrhoeae to block the adherence of the microorganism to epithelial cells. Thus far, these vaccines have proven effective in some animal studies and in a limited number of human challenge studies. The problems that remain are: lack of broad cross reactivity of the vaccines thus far developed poor immunogenicity of the important binding ligands both in terms of quality and quantity of antibody produced and inadequate stimulation of antibody response at the local site of infection.

The feasibility of using an anti-human immunoglobulin/human immunoglobulin/[125I]anti-human immunoglobulin 'sandwich' in a solid-phase radioimmunoassay to produce a standard curve which could be used to quantitate antigen-specific antibody of a particular immunoglobulin class was investigated. The amount of secondary antibody (SAb) bound was determined as a function of whether the primary antibody (PAb) was bound to its specific solid-phase antigen or by a solid-phase anti-human immunoglobulin. No significant difference between the two values was observed. Quantitation of antitetanus toxoid antibody by this method was in good agreement with quantitative precipitin tests. Comparison of SAb binding as a function of the way the PAb is bound was extended to class-specific PAb by use of murine monoclonal antibodies to meningococcal antigens. In most cases somewhat greater binding of SAb occurred when PAb was bound to antigen, but in several cases where low avidity antibody and/or poor quality antigens were used, greater SAb binding occurred when PAb was bound by anti-mouse immunoglobulin. The results indicate that this approach may be useful as a general method for standardizing the SPRIA and other solid-phase immunoassays such as the ELISA to measure class-specific antibody.

One hundred fourteen men with uncomplicated urethritis were randomized to receive 1 week of therapy with either doxycycline (100 mg twice daily) or ofloxacin (300 mg twice daily). Of the 109 men completing the post-treatment visit, 56 received ofloxacin and 52 (93%) were clinically cured. Forty four (83%) of the 53 men treated with doxycycline were cured. All 30 patients with gonorrhea (including three with penicillinase-producing Neisseria gonorrhoeae [PPNG] isolates) who were treated with ofloxacin became culture-negative, as compared with 32 of 34 patients receiving doxycycline. In contrast, three of 18 patients with Chlamydia trachomatis were microbiologic failures after ofloxacin therapy, while all ten treated with doxycycline were cured. Adverse effects of both treatment regimens were generally mild, and compliance was excellent except for one patient receiving doxycycline. These results show that ofloxacin, in a dosage of 300 mg taken orally twice daily for seven days, is an effective treatment for uncomplicated urethritis in men but may not reliably cure chlamydial infections.

A parenteral gonococcal pilus vaccine which has previously been shown to be safe and antigenic also results in the production of specific local genital antibody. All three major antibody classes were present in the local secretions, but immunoglobulin A predominated, a portion of which is dimeric 11S immunoglobulin A. This mucosal antibody is also capable of blocking the attachment of gonococci to epithelial cells. The antibody cross-reacted with five heterologous pili in a solid-phase radioimmunoassay. These results are encouraging and suggest that a gonococcal pilus vaccine may be efficacious in preventing gonorrhea.

To characterize the serum antibody response to urethral infection with Neisseria gonorrhoeae, we examined pre- and postinfection sera from 13 men experiencing their first gonococcal infection. Using western blot analysis, we found that nine of 13 patients developed new serum IgG antibodies against one or more antigens, most commonly against lipooligosaccharide, followed in order by the H.8-antigen, pili, proteins I and II, and protein III. Twelve of 13 patients had preexisting IgG to gonococcal antigens, most commonly against the H.8 antigen, followed by pili, lipooligosaccharide, protein I, and protein III. Using serum obtained from other patients before and after nasopharyngeal carriage of Neisseria meningitidis, we demonstrated that carriage resulted in serum IgG cross-reactive to N. gonorrhoeae antigens. This is likely explanation for the presence of antigen-specific antibody in preinfection sera.

Because of the high prevalence of penicillinase-producing Neisseria gonorrhoeae in the Republic of Korea, spectinomycin has been used there in the primary treatment of gonococcal infections in U.S. military personnel since 1981, but there have been increasingly frequent reports of treatment failures with spectinomycin. We conducted a clinical study to determine the efficacy of spectinomycin treatment in 124 U.S. servicemen in the Republic of Korea who had urethral gonococcal infections. Ninety-seven patients were treated with spectinomycin alone and evaluated in a follow-up visit. In eight patients (8.2 percent), this treatment was unsuccessful. Antibiotic-sensitivity testing on isolates from seven of the patients with treatment failure demonstrated that six isolates were highly resistant to spectinomycin (minimal inhibitory concentration, greater than or equal to 100 micrograms per milliliter). None of the spectinomycin-resistant strains had become resistant to penicillin, either through the production of penicillinase or through a chromosomal mutation. Although the mechanism of spectinomycin resistance appears to be a chromosomal mutation, these isolates were generally sensitive to other antibiotics. The prevalence of resistance to spectinomycin resulted in the substitution of ceftriaxone for the primary treatment of gonorrhea acquired by U.S. military personnel in the Republic of Korea. We believe that the rapid emergence of spectinomycin resistance in this population mandates a cautious approach to widescale use of the drug and indicates a need to broaden current surveillance programs.

The MICs for 41 Neisseria gonorrhoeae strains from patients receiving spectinomycin treatment were determined by the agar dilution method and compared with the zones of inhibition produced by disks containing 100 micrograms of spectinomycin. Our data demonstrated a good correlation between the two methods. Moreover, a zone of inhibition of less than or equal to 15 mm was a good predictor of clinical treatment failures with spectinomycin.