Wolfram Metzger

Immunoproteomics of Helicobacter pylori infection and relation to gastric disease

The Gram negative bacterium Helicobacter pylori is a human pathogen which infects the gastric mucosa and causes an inflammatory process leading to gastritis, ulceration and cancer. A systematic, proteome based approach was chosen to detect candidate antigens of H. pylori for diagnosis, therapy and vaccine development and to investigate potential associations between specific immune responses and manifestations of disease. Sera from patients with active H. pylori infection (n = 24), a control group with unrelated gastric disorders (n = 12) and from patients with gastric cancer (n = 6) were collected and analyzed for the reactivity against proteins of the strain HP 26695 separated by two‐dimensional electrophoresis. Overall, 310 antigenic protein species were recognized by H. pylori positive sera representing about 17% of all spots separated. Out of the 32 antigens most frequently recognized by H. pylori positive sera, nine were newly identified and 23 were confirmed from other studies. Three newly identified antigens which belong to the 150 most abundant protein species of H. pylori, were specifically recognized by H. pylori positive sera: the predicted coding region HP0231, serine protease HtrA (HP1019) and Cag3 (HP0522). Other antigens were recognized differently by sera from gastritis and ulcer patients, which may identify them as candidate indicators for clinical manifestations. The data from these immunoproteomic analyses are added to our public database (http://www.mpiib‐berlin.mpg.de/2D‐PAGE). This platform enables one to compile many protein profiles and to integrate data from other studies, an approach which will greatly assist the search for more immunogenic proteins for diagnostic assays and vaccine design.

Safety and immunogenicity of live recombinant Salmonella enterica serovar Typhi Ty21a expressing urease A and B from Helicobacter pylori in human volunteers

Helicobacter pylori urease was expressed in the common live typhoid vaccine Ty21a yielding Ty21a(pDB1). Nine volunteers received Ty21a(pDB1) and three control volunteers received Ty21a. No serious adverse effects were observed in any of the volunteers. Ten out of 12 volunteers developed humoral immune responses to the Salmonella carrier as detected by antigen-specific antibody-secreting cells but only two volunteers seroconverted. A total of five volunteers showed responses in one or two out of three assays for cellular responses to the carrier (proliferation, IFN-gamma-secretion, IFN-gamma-ELISPOT). Three of the volunteers that had received Ty21a(pDB1) showed a weak but significant T-cell response to Helicobacter urease, while no volunteer had detectable humoral responses to urease. Ty21a(pDB1) is a suitable prototype to optimize Salmonella-based vaccination for efficient cellular responses that could mediate protective immunity against Helicobacter.

Correlation of T cell response and bacterial clearance in human volunteers challenged with Helicobacter pylori revealed by randomised controlled vaccination with Ty21a-based Salmonella vaccines

Background: Helicobacter pylori remains a global health hazard, and vaccination would be ideal for its control. Natural infection appears not to induce protective immunity. Thus, the feasibility of a vaccine for humans is doubtful. Methods: In two prospective, randomised, double-blind, controlled studies (Paul Ehrlich Institute application nos 0802/02 and 1097/01), live vaccines against H pylori were tested in human volunteers seronegative for, and without evidence of, active H pylori infection. Volunteers (n = 58) were immunised orally with Salmonella enterica serovar Typhi Ty21a expressing H pylori urease or HP0231, or solely with Ty21a, and then challenged with 2×105 cagPAI− H pylori. Adverse events, infection, humoral, cellular and mucosal immune response were monitored. Gastric biopsies were taken before and after vaccination, and postchallenge. Infection was terminated with antibiotics. Results: Vaccines were well tolerated. Challenge infection induced transient, mild to moderate dyspeptic symptoms, and histological and transcriptional changes in the mucosa known from chronic infection. Vaccines did not show satisfactory protection. However, 13 of 58 volunteers, 8 vaccinees and 5 controls, became breath test negative and either cleared H pylori (5/13) completely or reduced the H pylori burden (8/13). H pylori-specific T helper cells were detected in 9 of these 13 (69%), but only in 6 of 45 (13%) breath test-positive volunteers (p = 0.0002; Fisher exact test). T cells were either vaccine induced or pre-existing, depending on the volunteer. Conclusion: Challenge infection offers a controlled model for vaccine testing. Importantly, it revealed evidence for T cell-mediated immunity against H pylori infection in humans.

Intravenous or intramuscular anti-HBs immunoglobulin for the prevention of hepatitis B reinfection after orthotopic liver transplantation

To prevent reinfection with hepatitis B virus after orthotopic liver transplantation, patients receive long-term intravenous anti-HBs immunoprophylaxis. We compared the pharmacokinetics of intravenously and intramuscularly administered commercially available hepatitis B virus immunoglobulins. The study group consisted of 12 patients on immunoprophylaxis after orthotopic liver transplantation, who were Hbs antigen negative; 11 were anti-HBe positive and one was HBe positive. The patients first received intravenous immunoglobulin, and six of them were then transferred to intramuscular immunoglobulin. Our findings show that with fortnightly intramuscular application of 1000 IU of anti-HBs, reproducible and stable antibody titers above 100 IU of anti-HBs can be achieved. Side effects of intramuscular immunoprophylaxis are minimal and the method is safe. The switch from intravenous (1500 IU of anti-HBs) to intramuscular (1000 IU of anti-HBs) reduced the cost of immunoprophylaxis by more than 50%.

High efficacy of short-term quinine-antibiotic combinations for treating adult malaria patients in an area in which malaria is hyperendemic.

In a randomized trial, a three-dose quinine monotherapy was compared with short-term combination regimens of quinine-clindamycin and quinine-doxycycline for treating adult Gabonese patients with Plasmodium falciparum malaria. In quinine-treated patients, only 38% were ultimately cured. In contrast, more than 90% of patients were cured after treatment with either combination regimen.

Loa loa—does it deserve to be neglected?

More than 10 million people in western and central Africa are estimated to be infected with Loa loa filarial nematodes. Like most other infectious diseases, L loa filariasis (loiasis) covers a wide range of symptoms. Severe complications have been reported; however, most observations are anecdotal, typically in travellers. The widespread use of filaricidal drugs within eradication programmes of Onchocerca volvulus and Wuchereria bancrofti led to the observation that concomitant L loa infection increases the risk of severe treatment-associated, life-threatening complications. Initiatives were therefore launched to map the risk of loiasis. Insight about the epidemiology of L loa has advanced notably; however, its effect on the individual as well as on the community level has not been well studied. In the absence of appropriate studies, L loa is commonly judged a harmless nematode, and loiasis as a separate entity does not belong to the list of neglected tropical diseases to be controlled or eradicated in worldwide campaigns. We advocate reorientation of research efforts towards a patient-centric view of loiasis and, as a first step, to establish the disease burden in disability-adjusted life-years of this chronic infection, and to answer the question of whether loiasis should be included in future control programmes.

A rapid malaria appraisal in the Venezuelan Amazon

BackgroundWhile the federal state of Amazonas bears the highest risk for malaria in Venezuela (2007: 68.4 cases/1000 inhabitants), little comprehensive information about the malaria situation is available from this area. The purpose of this rapid malaria appraisal (RMA) was to provide baseline data about malaria and malaria control in Amazonas.MethodsThe RMA methodology corresponds to a rapid health impact assessment (HIA) as described in the 1999 Gothenburg consensus. In conjunction with the actors of the malaria surveillance system, all useful data and information, which were accessible within a limited time-frame of five visits to Amazonas, were collected, analysed and interpreted.ResultsMortality from malaria is low (< 1 in 105) and slide positivity rates have stayed at the same level for the last two decades (15% ± 6% (SD)). Active case detection accounts for ca. 40% of slides taken. The coverage of the censured population with malaria notification points (NPs) has been achieved in recent years. The main parasite is Plasmodium vivax (84% of cases). The proportion of Plasmodium falciparum is on the decline, possibly driven by the introduction of cost-free artemisinin-based combination therapy (ACT) (1988: 33.4%; 2007: 15.4%). Monitoring and documentation is complete, systematic and consistent, but poorly digitalized. Malaria transmission displayed a visible lag behind rainfall in the capital municipality of Atures, but not in the other municipalities. In comparison to reference microscopy, quality of field microscopy and rapid diagnostic tests (RDTs) is suboptimal (kappa < 0.75). Hot spots of malaria risk were seen in some indigenous ethnic groups. Conflicting strategies in respect of training of community health workers (CHW) and the introduction of new diagnostic tools (RDTs) were observed.ConclusionMalaria control is possible, even in tropical rain forest areas, if the health system is working adequately. Interventions have to be carefully designed and the features of the particular local Latin American context considered.

Lessons from a modern review of the smallpox eradication files

Background Smallpox was declared eradicated in 1980. Nevertheless, the virus has not lost importance with contemporary biosecurity concepts contributing to the revival of smallpox research and new investigations in smallpox vaccines. In addition, eradication of smallpox is a frequently used argument in public debates about vaccine success. The statement ‘‘the vaccine has eradicated smallpox’’ often serves as an historical proof-of-concept for the high potential impact of vaccines for eliminating other pathogens, e.g. polio, measles and malaria. In the hot phase of the campaign, a series of studies were carried out to determine the transmission conditions of the virus. Data from these studies are cited as evidence that the protective efficacy of the vaccine was close to 100%. For example, data from five studies carried out in the end of the 1960s and early 1970s in two major Indian cities, and in rural communities of West Pakistan, are listed in the definitive book about smallpox eradication published by Fenner et al. on behalf of the World Health Organization (WHO). The five studies evaluated smallpox attacks in contact persons of index cases retrospectively. When an outbreak was reported, a team of WHO collaborators visited the families and traced the path of intrafamilial transmission. The vaccination status of family members was among the parameters gathered in the surveys. However, none of the case-control studies had the adequate design to determine vaccine efficacy. Nonetheless, the formula for calculating vaccine efficacy was applied: vaccine efficacy1⁄4 (1 R) 100, where R is the relative risk, i.e. the percentage of vaccinated persons with smallpox divided by the percentage of unvaccinated persons with smallpox. In the five publications, vaccine efficacy ranged between 91% and 97%. These data were reproduced in a single table on vaccine efficacy in Fenner et al. The smallpox fact sheet of the Centers of Disease Control and Prevention (CDC) mentioned at this point: ‘It is important to note, however, that at the time when the smallpox vaccine was used to eradicate the disease, testing was not as advanced or precise as it is today, so there may still be things to learn about the vaccine and its effectiveness . . .’