Immunolocalization of intercellular adhesion molecule-1 and leukocyte functional associated antigen-1 in schistosomal soluble egg antigen-induced granulomatous hyporesponsiveness.

In this work, the changes in expression of the adhesion molecules ICAM-1/LFA-1 on inflammatory cells of the liver were studied by immunohistochemistry. Mice sensitized with SEA and infected with S. mansoni and S. mansoni-infected controls were examined from day 35 to day 56 postinfection. A significant upregulation of ICAM-1 and LFA-1 in both the SEA group and the infected control group started shortly after egg deposition at day 35 and persisted up to day 56 p.i. Notably, both ICAM-1 and LFA-1 expression peaks were shifted earlier to day 38 p.i. in the SEA group compared to day 40 in the infected control group. The distribution of ICAM-1 and LFA-1 in both groups was comparable. At the early phase of infection before granuloma formation, both ICAM-1 and LFA-1 were detected along the sinusoidal wall of small blood vessels. At the acute cellular granuloma phase, they were homogeneously distributed all over the inflammatory cells, while at the chronic fibrocellular stage a non-homogeneous staining of granuloma cells at the periphery of the granuloma was apparent. The present data suggest that adhesion molecules play a role in the initiation and maintenance of granuloma formation. Thus, the granulomatous hyporesponsiveness induced by sensitization with SEA was associated with reduced expression of adhesion molecules.

Immunolocalization of macrophage adhesion molecule-1 and macrophage inflammatory protein-1 in schistosomal soluble egg antigen-induced granulomatous hyporesponsiveness.

This work studied the histopathological changes and the changes in the expression of macrophage adhesion molecule-1 (Mac-1) and macrophage inflammatory protein-1alpha (MIP-1alpha) in a murine model of soluble egg antigen (SEA) - induced granulomatous hyporesponsiveness. Histopathological results of hepatic sections in an SEA group showed early acceleration of ova destruction and markedly diminished granuloma cellularity with eosinophils and macrophages still being the predominant cells. Later, giant cells and pigmented macrophages that were scattered among granuloma cells and in intimate contact with the deposited eggs were more predominant in the SEA group than in the infected control group. Concurrently, the counts of Mac-1 positive cells were significantly increased in liver sections of the SEA group than the infected control group during the course of infection. MIP-1alpha showed early higher counts followed by lower counts in the later stages of infection on granuloma cells in the SEA group than the infected control group. During the course of infection, similar distribution of Mac-1 and MIP-1alpha was present in both groups. This study suggests that sensitization with SEA probably leads to enhancement of phagocytic activity of macrophages via increasing expression of Mac-1 and hence engulfment of ic3b coated schistosomal products such as ova. It leads to rapid destruction of ova and hence decreases the host inflammatory response to infection and amelioration of hepatic pathology which would be a promising approach in reduction of host morbidity and mortality.

Anti-miracidial effect of recombinant glutathione S-transferase 26 and soluble egg antigen on immune responses in murine schistosomiasis mansoni.

The anti-miracidial potential of recombinant Schistosoma mansoni glutathione S-transferase 26 (rSmGST26) or native crude soluble egg antigens (SEA) was assessed. The associated dynamics of granuloma formation and immune responses were evaluated. Naive C57BL/6 mice were injected intravenously with multiple doses of either SEA (SEA-group) or rSmGST26 (GST-group) 7 days before cercarial infection. The immunized groups and the respective controls were sacrificed 6, 8 and 16 weeks postinfection (p.i.). Acceleration of ova destruction and reduction of granuloma diameter were greater in the GST-group than the SEA-group, mainly at 8 weeks p.i. However, the amelioration of hepatic pathology and function was more evident in the SEA-group. Concurrently, serum-specific IgG1 levels were elevated throughout the course of infection in the immunized groups compared to the infected controls. Initial rise of all splenic cytokines and serum anti-SEA IgE levels at 6 weeks p.i. was observed, followed by a dramatic drop in the levels of the proinflammatory cytokines IL-2, IFNgamma, IL-4 and TNF-alpha and IgE at 8 weeks of infection. IL-10 level was lower at 8 weeks p.i. than at 6 weeks, but was higher in immunized groups than in infected controls. Several responses may be implicated as an outcome of the present immunization protocol, such as increased levels of blocking antibody (IgG1) and IL-10 with decreased levels of proinflammatory cytokines and IgE.

Phenotypic diversity of enterotoxigenic Escherichia coli strains from a community-based study of pediatric diarrhea in periurban Egypt.

No past studies of diarrhea in children of the Middle East have examined in detail the phenotypes of enterotoxigenic Escherichia coli (ETEC) strains, which are important pathogens in this setting. During a prospective study conducted from November 1993 to September 1995 with 242 children under 3 years of age with diarrhea living near Alexandria, Egypt, 125 episodes of diarrhea were positive for ETEC. ETEC strains were available for 98 of these episodes, from which 100 ETEC strains were selected and characterized on the basis of enterotoxins, colonization factors (CFs), and O:H serotypes. Of these representative isolates, 57 produced heat-stable toxin (ST) only, 34 produced heat-labile toxin (LT) only, and 9 produced both LT and ST. Twenty-three ETEC strains expressed a CF, with the specific factors being CF antigen IV (CFA/IV; 10 of 23; 43%), CFA/II (5 of 23; 22%), CFA/I (3 of 23; 13%), PCFO166 (3 of 23; 13%), and CS7 (2 of 23; 9%). No ETEC strains appeared to express CFA/III, CS17, or PCFO159. Among the 100 ETEC strains, 47 O groups and 20 H groups were represented, with 59 O:H serotypes. The most common O serogroups were O159 (13 strains) and O43 (10 strains). O148 and O21 were each detected in five individual strains, O7 and O56 were each detected in four individual strains, O73, O20, O86, and O114 were each detected in three individual strains, and O23, O78, O91, O103, O128, and O132 were each detected in two individual strains. The most common H serogroups were H4 (16 strains), 12 of which were of serogroup O159; H2 (9 strains), all of which were O43; H18 (6 strains); H30 (6 strains); and H28 (5 strains); strains of the last three H serogroups were all O148. Cumulatively, our results suggest a high degree of clonal diversity of disease-associated ETEC strains in this region. As a low percentage of these strains expressed a CF, it remains possible that other adhesins for which we either did not assay or that are as yet undiscovered are prevalent in this region. Our findings point out some potential barriers to effective immunization against ETEC diarrhea in this population and emphasize the need to identify additional protective antigens commonly expressed by ETEC for inclusion in future vaccine candidates.

Characterization of an enterotoxigenic Escherichia coli strain from Africa expressing a putative colonization factor.

An enterotoxigenic Escherichia coli (ETEC) strain of serotype O114:H- that expressed both heat-labile and heat-stable enterotoxins and tested negative for colonization factors (CF) was isolated from a child with diarrhea in Egypt. This strain, WS0115A, induced hemagglutination of bovine erythrocytes and adhered to the enterocyte-like cell line Caco-2, suggesting that it may elaborate novel fimbriae. Surface-expressed antigen purified by differential ammonium sulfate precipitation and column chromatography yielded a single protein band with M(r) 14,800 when resolved by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (16% polyacrylamide). A monoclonal antibody against this putative fimbrial antigen was generated and reacted with strain WS0115A and also with CS1-, CS17-, and CS19-positive strains in a dot blot assay. Reactivity was temperature dependent, with cells displaying reactivity when grown at 37 degrees C but not when grown at 22 degrees C. Immunoblot analysis of a fimbrial preparation from strain WS0115A showed that the monoclonal antibody reacted with a single protein band. Electron microscopy and immunoelectron microscopy revealed fimbria-like structures on the surface of strain WS0115A. These structures were rigid and measured 6.8 to 7.4 nm in diameter. Electrospray mass-spectrometric analysis showed that the mass of the purified fimbria was 14,965 Da. The N-terminal sequence of the fimbria established that it was a member of the CFA/I family, with sequence identity to the amino terminus of CS19, a new CF recently identified in India. Cumulatively, our results suggest that this fimbria is CS19. Screening of a collection of ETEC strains isolated from children with diarrhea in Egypt found that 4.2% of strains originally reported as CF negative were positive for this CF, suggesting that it is biologically relevant in the pathogenesis of ETEC.

Identification of Shigella flexneri subserotype 1c in rural Egypt.

In a population-based study of diarrhea in rural, northern Egypt, 60 Shigella flexneri strains were identified, of which 10 could not be definitively serotyped. Serological analysis with commercial reagents suggested that they were serotype 1, but the strains failed to react with subserotype 1a- or 1b-specific antibodies. All 10 strains reacted with MASF 1c, a monoclonal antibody specific for a provisional S. flexneri subserotype, 1c, first identified in Bangladesh and not previously detected outside of that region. Our results show that S. flexneri subserotype 1c is not unique to Bangladesh and that the inability to detect it may reflect both the limited use of suitable screening methods and the rarity of this subserotype.

Identification of surface tegumental antigens of normal and irradiated schistosomula.

Sodium dodecyl sulphate- poly acrylamide gel electronphoresis (SDS-PAGE) fractionation of tegumental surface antigens (STEG-Ags.) of 7-day cultured normal and irradiated schistosomula showed no obvious qualitative differences. The observed polypeptide bands of both normal irradiated STEG-Ags. were almost identical and have similar corresponding molecular weights. The immunoblotting assay, using different types of mouse sera, revealed similarity between the bands of both normal and irradiated STEG-Ags. recognized by each type of mouse serum. No qualitative rather than quantitative differences have been observed. The quantitative differences were reflected in intensively staining of some bands from normal STEG-Ag. rather than their corresponding bands of the same molecular weights from irradiated STEG-Ag.

Immunoregulatory potential of exogenous Schistosoma mansoni soluble egg antigen in a model of experimental schistosomiasis--I. Regulation of granuloma formation in vivo.

This study was undertaken to assess the optimum conditions required to reduce the vigorous host granulomatous reaction around Schistosoma mansoni eggs. Soluble schistosomal egg antigen (SEA) at a concentration of 10 or 100 micrograms protein was administered i.p. or i.v. into unprimed C57BL/6 mice. SEA was injected either alone or in combination with cyclophosphamide (CY) 100 or 50 mg/kg via i.p. route. Seven or 14 days later viable eggs of S. mansoni were injected via the tail vein into treated groups and untreated normal controls. Mice were sacrificed 8, 16 and 24 days after the injection of eggs. The lungs were removed for histopathological study, measurement of granuloma diameter and phenotypic analysis of granuloma intralesional T-cell subsets. Compared to untreated controls, the lower concentration of SEA (10 micrograms) administered by the i.v. route 7 days before egg injection, induced a significant reduction in granuloma diameter 16 days after egg injection than that by the i.p. route or at a higher SEA concentration (100 micrograms). Compared to untreated controls, the higher dose of CY (100 mg/kg), given i.p. alone or in combination with 10 micrograms SEA by the i.v. or i.p. route, induced a significant reduction in granuloma diameter, while 50 mg/kg CY did not cause any reduction. The reduction in granuloma diameter by i.v. administration of low SEA concentration alone or in combination with CY IP, was associated with a decrease in the granuloma intralesional L3T4+/Lyt2+ ratio. The decrease in the ratio was due to an increase in Lyt2+ cells. The results suggest that the use of low dose SEA by the i.v. route alone or combined with an immunosuppressive drug ameliorates pathological changes concurrent with S. mansoni infection.

Immunological response to diphtheria/tetanus vaccine in Schistosomiasis mansoni patients.

The cellular and humoral immune responses of patients with S. mansoni infection were evaluated before and one month after each of two intramuscular doses of diphtheria/tetanus toxoid vaccine. Patients were divided into "responder" and "non-responder" groups based on anti-tetanus toxoid (anti-TT) IgG levels after vaccination. The specific anti-TT IgG1 response of the responder group was predominantly in the IgG, subclass. The lymphoproliferative response to PHA was also significantly higher in the responder group; this elevation was detectable before and after each vaccination. The responses to PWM and SPL were comparable in the two groups before vaccination, although the responder group had a higher response to SPL after vaccination. IgG antibodies for schistosome adult worm and egg antigens were significantly lower in the responder group prior to vaccination but not thereafter. Anti-diphtheria IgG antibodies were comparable in the two groups after vaccination at all times. Clinically, the non-responder patients had a higher incidence of splenomegaly (84.6% vs 44.8%) and were significantly older than the responder patients (mean 34.1 yrs vs 18.7 yrs). The cause for the reduced anti-tetanus IgG response in schistosomiasis patients is believed to be multifactorial. T cell or antigen presenting cell dysfunction, high levels of IgG antibodies specific for schistosome antigens, splenomegaly and age are factors that might lead to reduced anti-TT IgG response.

Are tuberculosis wards a risk factor for HIV in Africa?

A twenty-year-old female prostitute had an indeterminant HIV western blot in Djibouti during June 1988. She was hospitalised at the tuberculosis hospital in October and was re-tested for HIV in November. Her western blot result was still indeterminant, despite a progressive profile, and she therefore escaped to the hospital's HIV surveillance system. There were strong indications that while in-hospital, the patient resumed the activities of her previous profession. We conclude that active tuberculosis may develop in African HIV patients prior to the development of a confirmatory HIV western blot profile. Thorough precautionary measures are indicated for preventing HIV from spreading to health care personnel and amongst hospitalised patients in Africa.

Safety and immunogenicity of a recombinant hepatitis B vaccine in patients infected with Schistosoma mansoni.

Thirty Egyptian males, 8-31 years of age, with active Schistosoma mansoni infection and negative serologic tests for hepatitis B markers, were vaccinated with a recombinant hepatitis B vaccine (Merck's Recombivax). The vaccine was given intramuscularly in the deltoid region in three 10 micrograms doses at 0, 1, and 6 months. All patients were treated with praziquantel 2 months after the first vaccination. Sera were collected every 2 months for 12 months and tested for anti-HBs using a quantitative ELISA technique. There were no side reactions except for mild local soreness at the injection site in 3 patients. At 12 months, all subjects seroconverted (antibody levels greater than 10 mIU/mL); 24 patients (80%) developed antibody levels greater than 1,000 mIU/mL. As with a plasma-derived vaccine, antibody levels were negatively correlated with increasing spleen size. A recombinant hepatitis B vaccine was safe and immunogenic when given to patients with schistosomiasis mansoni.

T lymphocyte subset modulation of hepatic fibroblast function in murine schistosomiasis.

We have previously shown that co-culture of T cell enriched spleen lymphocytes can reduce collagen synthesis and stimulate proliferative activity by liver fibroblasts from S. mansoni infected mice. The present study examines which subset of T cells is responsible for this modulation. Co-culture of fibroblasts with the total T cell population lead to significant stimulation in fibroblast proliferative activity and a significant decrease in the incorporation of 14C-proline into collagenase-sensitive protein. There was virtually no effect on total incorporation of 14C-proline in non-collagen proteins. An additional significant increase in fibroblast proliferative activity and another significant decrease in collagen synthesis accompanied by a 2-fold increase in non-collagen protein production was noted when fibroblasts were co-cultured with Lyt-1+ cells. Co-culture of fibroblasts with Lyt-2+ cells did not differ significantly from co-culture with total T cells. Mitomycin treatment of the lymphocytes blunted their specific effects, suggesting that proliferation of T cells is required for maximal exertion of their regulatory activity. These results suggest that the T cells which mediate these effects belong to the Lyt-1+ helper class and are distinct from the Lyt-2+ suppressor cells.

Maternal-infant transmission of hepatitis B in Egypt.

In order to determine whether maternal-infant (vertical) transmission of hepatitis B is a common route of infection leading to chronic antigenemia in Egypt, 901 asymptomatic women in labor were evaluated. Forty-three women (4.8 percent) were positive for HBsAg, but only one woman was positive for HBeAg. From one year of observation of children born to 13 of the HBsAg-positive mothers, vertical transmission of hepatitis B was estimated to have occurred in approximately 1.7% of births, with chronic antigenemia resulting from 0.6% of births. It was also possible to observe 29 children born to women negative for HBsAg. Horizontal transmission of hepatitis B occurred in 17.2 percent of these children during the first year of life. Maternal-infant transmission of hepatitis B at birth does not appear to be the predominant mechanism of hepatitis B transmission or a common cause of chronic antigenemia in Egypt. The first year after birth appears to be a more important period of hepatitis B transmission. Therefore, vaccination of all children at birth with hepatitis B vaccine could be an effective vaccine strategy despite a low incidence of vertical hepatitis B transmission.

Immunogenicity of hepatitis B vaccine in patients infected with Schistosoma mansoni.

Because dual infection with Schistosoma mansoni and hepatitis B may lead to severe liver disease, populations living in schistosomiasis-endemic areas might benefit if effectively immunized against hepatitis B. To determine whether a plasma-derived hepatitis B vaccine is immunogenic in patients with schistosomiasis, 32 individuals infected with S. mansoni were given three 20-micrograms doses of Heptavax-B vaccine and treated with praziquantel. Antibody to hepatitis B surface antigen developed in 90.6% of the study subjects after three doses of vaccine. Five patients (15.6%) had a weak response to the vaccine, and three patients (9.4%) failed to develop antibody. A weak or failed response to the vaccine was significantly associated with the presence of hepatosplenomegaly. A plasma-derived vaccine is immunogenic for persons infected with S. mansoni; however, vaccine response is diminished in hepatosplenic schistosomiasis.

Non-A, non-B hepatitis in Omdurman, Sudan.

One-hundred nineteen patients (cases) at least 13 years of age with acute hepatitis were studied to determine the viral etiology of acute hepatitis in Omdurman, Sudan. Ninety-eight control subjects (controls) were also evaluated to determine the risk factors associated with the development of clinical disease. Acute hepatitis non-A, non-B was diagnosed in 88 cases (73.9%), hepatitis B in 15 cases (12.6%), delta infection in 15 (12.6%), and hepatitis A in just one patient (0.8%). A higher percentage of hepatitis B cases had received a parenteral injection for medical therapy during the previous 6 months than control subjects (26.7% vs 4.1%, p less than 0.05). The data in this study indicate that hepatitis non-a, non-B may be the major cause of acute hepatitis in adults in this area of Sudan. The suggested association of parenteral therapy with the transmission of hepatitis B could have important implications for the spread of other parenterally-transmitted diseases.

Risk of hepatitis B infection among Egyptians infected with Schistosoma mansoni.

Three hundred twenty-four individuals in a farming village located in the Nile Delta of Egypt were serially tested for hepatitis markers and Schistosoma mansoni to determine whether there is an increased risk of hepatitis B in persons infected with schistosomiasis. One-half of the subjects had stools positive for S. mansoni. Thirty-seven percent of the individuals had been infected with hepatitis B, and 3% were chronic HBsAg carriers. No statistical association was found between S. mansoni infection and hepatitis B infection, including chronic hepatitis B. Although there was no evidence of an association between these 2 pathogens, larger nonhospital based studies are needed to resolve this question.

Acute sporadic hepatitis in adults living in Cairo, Egypt.

A group of 295 adult male patients from Cairo, Egypt, with acute hepatitis were studied. Acute hepatitis A was diagnosed in 8 patients (2.7%), hepatitis B in 115 (38.9%), delta infection in 19 (6.4%) and possible Epstein-Barr virus or cytomegalovirus-mediated hepatitis in 7 patients (2.4%). The remaining 146 patients (49.5%) were considered to have hepatitis non-A non-B. The clinical presentation of the various causes of hepatitis was similar, although patients with hepatitis B and delta infection had significantly higher mean alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels than patients diagnosed as having hepatitis non-A non-B. Various risk factors for the acquisition of hepatitis were evaluated. A history of an injection for medical treatment and a history of anti-schistosomal therapy were significantly associated with delta infection when compared to patients with either hepatitis B or non-A non-B (P less than 0.05). Hepatitis non-A non-B is a major cause of acute hepatitis in adults living in Cairo, and an iatrogenic source of infection may be important in the epidemiology of delta infection.