Immune responses in normal Indian langur monkeys (Presbytis entellus)--a primate model for visceral leishmaniasis

The Indian langur monkey (Presbytis entellus) is an experimental host for a range of human diseases and for the assessment of vaccine candidate antigens to some common parasitic infections. This experimental host is particularly suitable for the follow-up of immunological responses. To understand some of the mechanism that underlies the defense against experimental pathogens there is a need of the basic knowledge on antibody and cell mediated immune responses. In the present study 25 naïve monkeys were subjected to for assessment of their antibody responses to various human parasitic antigens as well as mitogen induced cellular responses. Only few monkeys were found to have low titer of antiparasitic antibodies. There was compressive dose dependent proliferative response of peripheral blood mononuclear cells. Unlike humans, the blastogenic as well as cytokine responses (IFN-gamma, IL-2 and IL-4) to Con A was considerably higher as compared to PHA. These findings are similar to what have been reported in other non-human primates, confirming the appropriateness of Indian langurs for pre-clinical trials.

Human S-antigen: peptide determinant recognition in uveitis patients

Uveitis is an inflammation of the uveal tract and is one of the major causes of visual impairment. Several lines of evidence suggest an important role for activated T lymphocytes in the perpetuation of posterior uveitis. In sequel to our preliminary observations with human S-antigen, we have further investigated the proliferative response of peripheral blood lymphocytes of posterior uveitis patients against 20 linear and 9 overlapping peptides of retinal S-antigen. The expression of surface markers CD4, CD8, CD29, CD45RA in peripheral blood was detected by flow cytometry. We have also assessed the pattern of cytokines present in peripheral blood mononuclear cells (PBMCs) using ribonuclease protection assay (RPA). Nineteen out of 32 patients' lymphocytes showed proliferative response to S-antigen, one or more of its 20 linear and nine overlapping synthetic peptides. Six patients showed significant lymphoproliferative response against various peptides. The maximum response was found to peptides from the 231-270 amino acid region of human S-antigen sequence. The percentage of CD29(+) (memory cells) and CD45RA(+) (naive cells) T-lymphocytes was higher in patients compared to healthy volunteers. There was a demonstrable difference in the percentage of CD4(+) and CD8(+) lymphocytes in the patients (P <== 0.05) as compared to controls. Higher message for interleukin (IL)-5, IL-10, IL-15, IL-9, IL-2, IL-13, and interferon (IFN)-gamma was observed in uveitis patients than in healthy individuals. In brief, our study suggests that a particular region of S-antigen plays an important role in idiopathic uveitis.

Contact of Entamoeba histolytica with baby hamster kidney-21 (BHK-21) cell line on cysteine proteinase activity

BACKGROUND & OBJECTIVES

Entamoeba histolytica, the causative agent of amoebiasis and amoebic liver abscess, lyses host cells by direct contact using surface lectins and releases cysteine proteinase (CP). Virulence of E. histolytica is directly related to activity of its CP. The relationship of CP activity and cytotoxicity has not been established. The present study was carried out to explore the events following contact of E. histolytica with target cells.

METHODS

Protease activity of E. histolytica was measured by azocaseine and haemoglobin assays, and cysteine proteinase activity was assessed by substrate gel electrophoresis. Target cell lysis was measured by chromium release assay.

RESULTS

Protease activity of E. histolytica was increased 2.5-fold following contact with BHK-21 cell line. CP activity of trophozoites alone was visualized at position 56, 35 and 29 kDa in substrate gel electrophoresis. Contact of trophozoites with target cells augmented the cytotoxic activity of amoebic CP. The increase in CP activity seen by substrate gel electrophoresis and cytotoxicity assay was blocked by pretreatment with E 64, a specific CP inhibitor and GalNAc, a contact inhibitor.

INTERPRETATION & CONCLUSION

The present data showed the involvement of amoebic CP in cytotoxicity and that the CP activity was enhanced on lectin-mediated contact of E. histolytica to the target cells. Further studies need to be done to understand the mechanism at the molecular level.

A serological study of intrafamilial spread from patients with sporadic hepatitis E virus infection

Intrafamilial transmission is rare in epidemic hepatitis E; its frequency in sporadic hepatitis E is not known. We followed up 86 household contacts (age range 4-75 years, mean +/- SD 32.4 +/- 15.8; 49 males), who were family members of patients with acute sporadic hepatitis E. Of the 86 contacts, 68 (79%) tested negative for IgG anti-hepatitis E virus antibodies. Four (4.7%) had IgM anti-hepatitis E virus antibodies at the time of diagnosis of hepatitis E in the index case; two of these contacts possibly had hepatitis E virus infection acquired simultaneously with that in the index case, and two could have had intrafamilial transmission. None developed serological evidence of hepatitis E virus infection over a period of 49 +/- 18 days after the diagnosis of index case, although a majority lacked IgG antibodies to hepatitis E virus and were likely to be susceptible. This suggests that person-to-person transmission is uncommon in sporadic hepatitis E.

Prophylactic potential of autoclaved Leishmania donovani with BCG against experimental visceral leishmaniasis

The prophylactic efficacy of autoclaved Leishmania donovani (ALD) and autoclaved L. major (ALM)--a heterologous vaccine developed against cutaneous leishmaniasis (used as a reference vaccine), along with BCG--was evaluated against L. donovani in hamsters (Mesocricetus auratus). Animals were immunized with triple doses (21 days apart) of either ALD or ALM (1.0 mg) with or without BCG (0.1 mg) and challenged 21 days later with 1 x 10(6) L. donovani amastigotes intracardially. Animals immunized with ALM + BCG and ALD + BCG yielded 94.3% and 86.1% parasite inhibition respectively in comparison to the BCG only and unvaccinated controls. Fifty and 33.3% of the vaccinated animals (ALM + BCG and ALD + BCG respectively) were completely devoid of parasites when tested on day 45 post-challenge (p.c.) and survived till the experiment was terminated. The mean survival of ALM + BCG and ALD + BCG groups (animals harbouring parasites) was longest (168 and 139 days respectively). No significant increase in anti-leishmanial antibody level (ELISA) was noticed in ALD + BCG and ALM + BCG groups whereas it increased progressively in the rest of the experimental groups. The lymphoproliferative responses to PHA and Con A, of the 2 vaccinated groups were comparable to that of normal controls on day 45 p.c. The study suggests that ALD along with BCG can offer substantial protection against visceral leishmaniasis in hamsters.

Occult hepatitis B virus infection as a cause of cirrhosis of liver in a region with intermediate endemicity

BACKGROUND

Serological tests may fail to identify hepatitis B virus (HBV) infection as a cause of liver cirrhosis in a proportion of patients. The frequency of such occult infection in regions with intermediate HBV endemicity is not known. Such cases may be diagnosed by incremental testing for IgG anti-HBc, serum HBV DNA, and HBV DNA in liver tissue.

METHODS

We tested sera of 111 patients with cirrhosis, including 39 with history of significant alcohol ingestion, for HBsAg, anti-HBc and serum HBV DNA. In addition, in a subset of 14 patients, HBV DNA was looked for in liver tissue.

RESULTS

On HBsAg and anti-HBc testing, 66 patients had HBV infection. Serum HBV DNA testing identified HBV infection in 13 additional cases. Of 18 patients labeled as 'cryptogenic' on serological testing, HBV DNA was detected in the serum in 7 patients. Of 14 patients in whom paired liver tissue and serum specimens were tested, 4 additional patients with HBV infection were detected after liver biopsy analysis.

CONCLUSIONS

Serological tests for HBsAg and anti-HBc antibody are insensitive in identifying HBV infection in patients with liver cirrhosis. HBV DNA testing in serum and liver can help in establishing HBV infection as etiology, either alone or in addition to another cause.

Frequency of infection by hepatitis B virus and its surface mutants in a northern Indian population

INTRODUCTION

The reported prevalence of hepatitis B virus (HBV) infection in the Indian general population varies from 2% to 11%. Epidemiological studies conducted so far have selection biases, since these included populations of defined age group, gender, social class, high-risk group, etc. The present study was designed to look for the molecular epidemiology of HBV infection in the rural and urban general populations in India.

METHODS

Sera obtained from healthy volunteers during college and social service camps from parts of northern India were tested for HBsAg and anti-HBc using enzyme immunoassays and for HBV DNA using polymerase chain reaction and Southern blot hybridization. The amplification products were cloned and sequenced, and nucleotide and deduced amino acid sequences of the surface and polymerase genes were analyzed for mutations.

RESULTS

Of the 730 subjects (rural 543, urban 187), 15 (2.1%) tested positive for HBsAg and 143 (19.5%) for anti-HBc; 10 were positive for both. The overall HBV exposure rate in the population was 20.3% (148/730). The HBsAg carrier rate was similar in the urban and rural populations (1.5% and 2.3%; p=ns), and anti-HBc positivity was lower in the urban population (8.5% vs. 23.3%; p<0.01). History of parenteral interventions or blood transfusion was associated with markers of exposure to HBV (10.2% vs. 4.6%; p=0.01). Among the 220 representative samples tested for HBV DNA, 14 (6.4%) were positive; of these, only four were positive for HBsAg or anti-HBc. Sequencing of a 388-nt segment of the S-gene from three individuals (two adw and one ayw subtype) revealed four mutations. Two and three of these led to amino acid changes in the HBV surface and polymerase genes, respectively; alterations in known cytotoxic T cell epitopes of HBV surface and polymerase proteins were observed in one individual each. None had the G587A mutation, which is known to be associated with loss of the 'a' determinant of HBsAg.

CONCLUSION

Our study shows a high frequency of exposure to HBV infection in the Indian general population; a proportion of HBV infected persons were detectable only by molecular methods. The positivity rate was higher in the rural population.

Tropical sprue is associated with contamination of small bowel with aerobic bacteria and reversible prolongation of orocecal transit time

BACKGROUND

In tropical sprue (TS), response to antibiotics may suggest a role for bacterial contamination of the small bowel, which is known in diseases with prolonged orocecal transit time (OCTT).

METHODS

We studied 13 patients with TS (diagnosed by standard criteria) for frequency, nature and degree of bacterial contamination of the small bowel by quantitative culture of jejunal aspirate, glucose hydrogen breath test (GHBT), and OCTT by lactulose hydrogen breath test before and after treatment. Twelve patients with constipation-predominant irritable bowel syndrome (IBS) and 12 healthy subjects served as controls.

RESULTS

Ten of 13 patients with TS had bacterial contamination compared with 3/12 with IBS (all aerobic, P < 0.05). Median colony count in TS (36 000 CFU/mL, 400 to > 100 000) was higher than IBS (700 CFU/mL, 100-1000, P < 0.05). Gram-negative aerobic bacilli were commonly isolated in TS but not in IBS. Median OCTT was longer in TS (180 m, 40 - 240) than IBS (110 m, 70 - 150, P = 0.008) and healthy subjects (65 m, 40 - 110, P = 0.0007, Wilcoxon rank sum test). Orocecal transit time in TS correlated with fecal fat (Spearman's rank correlation coefficient 0.69, P < 0.05). Orocecal transit time and fecal fat, repeated in 8/13 patients, decreased with treatment for TS (195 m, 130-240 vs 125 m, 90-200, P = 0.02; 8 g/24 h, 6.8-19.6 vs 7 g/24 h, 4.2-9, P = 0.04, respectively).

CONCLUSION

Aerobic bacterial contamination of the small bowel is common in patients with TS. Prolonged OCTT in TS correlated with fecal fat and normalized in a subset of patients after treatment.

High frequency of hepatitis B virus infection in patients with beta-thalassemia receiving multiple transfusions

BACKGROUND AND OBJECTIVES

Hepatitis B virus (HBV) may occasionally be transmitted through transfusion of blood units that are hepatitis B surface antigen (HBsAg) negative but HBV DNA positive. Children with beta-thalassemia are particularly susceptible to HBV because they receive multiple blood transfusions. These children have high infection rates despite vaccination against HBV. Post-vaccination infections may be a result of viruses harbouring surface (S)-gene mutations (e.g. G587A) in a region critical for reactivity to antibody to hepatitis B surface antigen (anti-HBs). The true prevalence of HBV in individuals with beta-thalassemia has not been studied previously.

PATIENTS AND METHODS

Seventy patients with beta-thalassemia (median age 6 years; range 8 months to 22 years; 49 male), who had received seven to 623 (median 61) units of blood each and three doses (10/20 micro g) of HBV vaccine (Engerix B) before presentation to us, were included in the study; 50 of the 70 patients had received transfusions prior to vaccination. Enzyme-linked immunoassay for serological markers [HBsAg, antibody to hepatitis B core antigen (anti-HBc) and quantitative anti-HBs] and polymerase chain reaction (PCR) followed by Southern hybridization for molecular detection of hepatitis B, was performed on all samples. The PCR-amplified product was cloned, sequenced and the nucleotide and deduced amino acid sequences for the HBV S and polymerase (P) genes were analysed for mutations.

RESULTS

Four of 70 (5.7%) individuals with beta-thalassemia were HBsAg positive and 14 (20%) were anti-HBc positive. The prevalence of serological markers increased with number of transfusions (P < 0.01). Of 70 patients, 53 (75.7%) had an anti-HBs titre of > 10 IU/l following vaccination and 17 (24.3%) were non-responders (< 10 IU/l); 22 (31.4%) of the 70 were DNA positive. The frequency of HBV infection in beta-thalassemia was similar in vaccine responders and non-responders. The virus was of subtype ayw (genotype D) in the five DNA-positive samples in which a 388-nucleotide region of the S gene was sequenced. Mutations occurred at 13 positions in the S gene and at 10 positions in the P gene. Hydrophobicity plots revealed differences in amino acid regions 117-165 and 195-211. Some of these amino acid substitutions coincided with the putative cytotoxic T-lymphocyte epitopes of both S and P proteins.

CONCLUSIONS

A high frequency of HBV infection was seen using molecular methods in thalassemic patients. The frequency of infection was similar in vaccine responders and non-responders. A number of mutations were observed in the S gene, which could have implications for viral replication as well as virus-host cell interaction.

Low response to HBsAg vaccine in chronic renal failure patients is not due to intrinsic defect of B cells

OBJECTIVE

The aim of this study was to investigate whether the inability of chronic renal failure patients to mount an adequate antibody response following hepatitis B vaccination was due to an inherent defect in the antibody producing capacity of their B cells.

MATERIAL AND METHODS

Peripheral blood mononuclear cells of end stage renal disease (ESRD) patients, who were not on maintenance hemodialysis (CRF) and those undergoing long-term hemodialysis (HD) were stimulated in vitro with pokeweed mitogen, a B cell mitogen or hepatitis B surface antigen. The total immunoglobulin (IgG, IgM and IgA) levels and anti-HBs specific IgM and IgG were quantitiated by sandwich ELISA and levels between patients who had a good antibody response in vivo and those who failed to mount an antibody response were compared.

RESULTS

Spontaneous IgG production was significantly higher than normals in CRF and HD group; PWM induced IgM, IgG and IgA production was comparable to normals in both groups of patients. The spontaneous IgG and PWM stimulated IgM and IgG production was significantly higher in HD patients as compared to CRF. The in vitro Ig levels in the vaccine responders and non-responders was comparable except for the spontaneous IgG which was highest in the responders. The in vitro anti-HBs production was comparable in HB vaccine responders and non-responders; the in vivo and in vitro anti-HBs titers showed a significant correlation coefficient thereby indicating that the in vitro assay reflects the in vivo functional status of B cells.

CONCLUSION

Our results demonstrate that the B cells in ESRD patients are functionally normal and cannot be the cause of the compromised vaccine response in these patients.

Urinary interleukin-8 predicts the response of standard and low dose intravesical bacillus Calmette-Guerin (modified Danish 1331 strain) for superficial bladder cancer

PURPOSE

We determined whether the proinflammatory cytokine interleukin-8 (IL-8) can serve as a predictor for the response to standard (120 mg.) and low (40 mg.) dose intravesical bacillus Calmette-Guerin (BCG) (modified Danish 1331 strain) for managing superficial bladder cancer in patients at risk for recurrence and progression.

MATERIALS AND METHODS

We randomized 26 patients with superficial bladder cancer to receive a 6-week course of standard dose 120 mg. or low dose 40 mg. intravesical BCG. Voided urine samples were collected immediately before and after (2 and 4 hours) BCG instillation. Urine samples were centrifuged at 1,500 rpm for 8 minutes and stored at -80C. IL-8 was measured using a commercial enzyme-linked immunosorbent assay. Patients were monitored for recurrence, progression and side effects of BCG treatment at 3-month intervals.

RESULTS

At a median followup of 24 months (range 12 to 30), 5 and 6 patients who received a standard and low dose, respectively had disease recurrence and/or progression (nonresponders). At 4 hours after BCG mean Il-8 levels plus or minus SD were significantly higher in responders than in nonresponders (1,099.33 +/- 708.51 versus 261.82 +/- 182.66 pg./ml., p = 0.001). There was no difference at 4 hours in mean IL-8 levels in the standard and low dose groups (596.92 +/- 546 and 893 +/- 798.67 pg./ml., respectively, p = 0.28). In all patients who remained disease-free IL-8 levels were greater than 400 pg./ml. In 9 of the 11 patients with disease recurrence/progression IL-8 levels were less than 400 pg./ml.

CONCLUSIONS

IL-8 secretion after the initial intravesical BCG instillation strongly correlates with the possibility of future recurrence/progression. The quantitative IL-8 response to low and standard dose intravesical BCG (Danish 1331) is similar.

Urinary interleukin-8 predicts the response of standard and low dose intravesical bacillus Calmette-Guerin (modified Danish 1331 strain) for superficial bladder cancer

PURPOSE

We determined whether the proinflammatory cytokine interleukin-8 (IL-8) can serve as a predictor for the response to standard (120 mg.) and low (40 mg.) dose intravesical bacillus Calmette-Guerin (BCG) (modified Danish 1331 strain) for managing superficial bladder cancer in patients at risk for recurrence and progression.

MATERIALS AND METHODS

We randomized 26 patients with superficial bladder cancer to receive a 6-week course of standard dose 120 mg. or low dose 40 mg. intravesical BCG. Voided urine samples were collected immediately before and after (2 and 4 hours) BCG instillation. Urine samples were centrifuged at 1,500 rpm for 8 minutes and stored at -80C. IL-8 was measured using a commercial enzyme-linked immunosorbent assay. Patients were monitored for recurrence, progression and side effects of BCG treatment at 3-month intervals.

RESULTS

At a median followup of 24 months (range 12 to 30), 5 and 6 patients who received a standard and low dose, respectively had disease recurrence and/or progression (nonresponders). At 4 hours after BCG mean Il-8 levels plus or minus SD were significantly higher in responders than in nonresponders (1,099.33 +/- 708.51 versus 261.82 +/- 182.66 pg./ml., p = 0.001). There was no difference at 4 hours in mean IL-8 levels in the standard and low dose groups (596.92 +/- 546 and 893 +/- 798.67 pg./ml., respectively, p = 0.28). In all patients who remained disease-free IL-8 levels were greater than 400 pg./ml. In 9 of the 11 patients with disease recurrence/progression IL-8 levels were less than 400 pg./ml.

CONCLUSIONS

IL-8 secretion after the initial intravesical BCG instillation strongly correlates with the possibility of future recurrence/progression. The quantitative IL-8 response to low and standard dose intravesical BCG (Danish 1331) is similar.

Gold sodium thiomalate (GSTM) inhibits lipopolysaccharide stimulated tumor necrosis factor-alpha through ceramide pathway

TNF-alpha has emerged as the major pro-inflammatory cytokine involved in the pathogenesis of rheumatoid arthritis (RA). LPS is a potent stimulator of TNF-alpha production by human monocytes. Ceramide, a structural homolog of LPS and a second messenger in the sphingomyelin signal transduction pathway has been shown to stimulate TNF-alpha production from murine macrophages. We have previously shown that GSTM, an anti-rheumatic drug inhibits LPS stimulated TNF-alpha production by normal PBMCs. We studied the ability of ceramide to stimulate TNF-alpha production by human PBMCs and the mechanism of action of GSTM on ceramide and LPS induced TNF-alpha production. LPS induced significant TNF-alpha production in PBMCs and THP-1. However, C(2) ceramide stimulated TNF-alpha production in 5 of 10 PBMCs (ceramide responder); it did not do so in the other 5 PBMCs (ceramide non-responder) or the THP-1 cell line. GSTM inhibited LPS stimulated TNF-alpha productions in PBMCs of all 5 ceramide responders both at protein and mRNA expression level. We also found that GSTM inhibited LPS induced NF-kappaB level only in ceramide responder. Thus, we for the first time report that GSTM inhibits LPS stimulated TNF-alpha production through ceramide pathway and anti-inflammatory activity of GSTM in treatment of RA may depend on its ability to inhibit NF-kappaB activation and TNF-alpha production.

Evidence for activation of cellular immune responses in patients with acute hepatitis E

INTRODUCTION

Although acute hepatitis E virus (HEV) infection is known to induce IgM and IgG humoral host immune responses, little is known about occurrence of cellular responses in this infection. We looked for evidence of lymphocyte sensitization to HEV peptides in patients with acute HEV infection.

METHODS

peripheral blood lymphocytes were obtained from patients with acute hepatitis E and healthy controls. Proliferation of these lymphocytes in the presence of each of seven peptides with amino acid sequences corresponding to open reading frames 2 and 3 proteins of HEV (3 and 4 peptides, respectively) were studied; no peptide was added to control wells. Proliferative responses with stimulation indices exceeding 3.0 were taken as positive.

RESULTS

More patients showed reactivity to two or more HEV peptides than did controls (11/21 vs 5/22, p<0.05). Reactivity to one peptide corresponding to open reading frame 2 of HEV was more frequent in patients than in controls (7/21 vs 1/22, p<0.05).

CONCLUSION

Our results show that lymphocytes of patients with acute hepatitis E show sensitization to HEV peptides. This may have significance in understanding the pathogenetic mechanisms of liver injury in this infection.

Drug sensitivity assay for leukaemic cells by flow cytometry

BACKGROUND & OBJECTIVES

Drug sensitivity assays are useful in oncology practice for evaluating the sensitivity of malignant cells to anti-cancer drugs. The usefulness of such assays for the prediction of clinical response to therapy has also been demonstrated. The existing methods used for this purpose are time consuming and labour intensive. Here we report a simplified flow cytometry based assay for evaluating the in vitro drug sensitivity of leukaemic cells.

METHODS

The chemo-sensitivity of three human leukaemic cell lines (a lymphoblastoid cell line, Jurkat; an erythroleukaemic cell line, K 562 and a myelomonocytic cell line HL-60) was investigated by flow cytometry. Flow cytometry was used to determine LD50 (50% inhibitory concentration) for prednisolone on Jurkat and daunorubicin on HL 60 and K 562 cell lines respectively. Per cent cell death could directly be assessed on a flow cytometer by measuring the fluorescence after staining with propidium iodide (PI). For comparison MTT assay was also performed using prednisolone on Jurkat and daunorubicin on HL-60.

RESULTS

Cytotoxic effect of drugs was found to be dose dependent. Mean LD50 of prednisolone for Jurkat cells by flow cytometry was 0.805 +/- 0.058 mg/ml and by MTT assay 0.866 +/- 0.115 mg/ml. Mean LD50 of daunorubicin for HL-60 was 1.96 +/- 0.05 micrograms/ml by flow cytometry and 1.90 +/- 0.282 micrograms/ml by MTT assay. The mean LD50 of daunorubicin to K 562 was 0.49 +/- 0.049 mg/ml by the flow cytometry method. The inter-assay variation for the LD50 by flow cytometry based assay was found to be 6, 14 and 10 per cent for Jurkat, HL-60 and K 562 respectively.

INTERPRETATION & CONCLUSION

We report a flow cytometry based drug-sensitivity assay for leukaemic cells, which uses a single dye staining and is rapid, technically simple and reproducible. The results compare well with the more commonly used MTT assay, which is labour intensive and time consuming. The limitation of our method is that it can only be used for studying cells in suspension and is therefore not suitable for adherent cell lines.

Establishment of asymptomatic Leishmania donovani infection in Indian langurs (Presbytis entellus) through intradermal route

Indian langurs, which were previously reported to be highly susceptible, were infected intradermally using variable numbers of promastigotes along with different doses, 1/2 pair, 5 pairs and 10 pairs respectively of salivary gland lysate (SGL). Although, all the monkeys developed mild infection and remained subclinically infected throughout the observation period, which later resolved, none of them could develop the classical disease. No marked antigen specific antibody or lymphoproliferative response was noticed throughout the experimental period. However, a late IFN-gamma response (by day 90 pi.) was demonstrated in monkeys infected with 2 x 10(6) promastigotes +10 pairs SGL. It seems that a single intradermal dose of promastigotes with or without SGLs had a vaccines like effect. Perhaps, multiple frequent inoculations, as happens in the natural situation, may be necessary for the development of full-blown disease.

Role of travel as a risk factor for hepatitis E virus infection in a disease-endemic area

BACKGROUND

We undertook epidemiologic and laboratory studies during an epidemic of acute hepatitis in Sindri town, in District Dhanbad, Bihar in 1998.

METHODS

A sample survey covering 201 randomly selected houses in the town was conducted during the epidemic, and records of patients admitted to the only large hospital in this town were reviewed. We also tested serum and stool specimens from some of the affected persons for hepatitis E virus (HEV) RNA and IgM anti-HEV antibodies.

RESULTS

Of the 1088 persons residing in the surveyed houses, 82 (7.54%) had developed acute hepatitis during the outbreak. Attack rate was higher among male residents than among female residents (71/604 vs. 11/484; 11.75% vs. 2.27%; relative risk [RR] 5.17 [95% confidence interval 2.77-9.65]; p<10(-6)) and was the highest in the 10-29 year age group. Hospital admission data showed similar age and gender distribution. Disease occurrence had no relation with source of drinking water (handpump 7.56% vs. municipal tap 7.53%; p=ns), or with habit of boiling (RR 1.10 [0.61-1.98]; p=ns) or filtering (RR 0.59 [0.33-1.06]; p=ns) water before drinking. Jaundice occurred more frequently among persons who had traveled outside Sindri town during the last two months than among those who had not (26.4% vs. 4.7%; RR 5.67 [3.81-8.43]; p<10(-6)); this risk persisted after correction for age (Mantel-Haenszel weighted OR 6.74 [4.12-11.01]; p<10(-6)). Men traveled more frequently than women and were more often affected. In multivariate analysis, travel and male gender were the only two independent risk factors. Data from a hospital in a neighboring large city, Dhanbad, suggested that there was an outbreak of hepatitis in that city too at the same time. Seventy-three of the 1088 study subjects had history of jaundice in the past; disease attack rate among these persons (9.6%) was similar to that among those without such history (7.5%; RR 1.31 [0.49-2.98]; p=ns). Of the 13 sera tested, 10 were positive for IgM anti-HEV. HEV RNA was detected in 9 of the 12 stool specimens and 10 of the 13 sera tested.

CONCLUSIONS

The hepatitis epidemic in Sindri was caused by HEV and had several features resembling those of previous HEV epidemics. However, the occurrence of hepatitis E showed a strong relationship with history of travel, a finding not hitherto described.

Successful vaccination against Leishmania donovani infection in Indian langur using alum-precipitated autoclaved Leishmania major with BCG

Autoclaved Leishmania major (ALM) along with BCG, presently undergoing phase II clinical trial by WHO for its vaccine potential against cutaneous leishmaniasis, has been successfully evaluated in single and triple dose schedules against L. donovani in Indian langurs (Presbytis entellus). Encouraged with the results, another formulation alum-precipitated ALM (provided by WHO) along with BCG has been evaluated in this system. Eight monkeys were vaccinated with alum-precipitated ALM + BCG (1 mg of each per animal) while four were kept as unvaccinated controls. All were challenged with 100 x 10(6) amastigotes i.v. on day 60 post vaccination. Parasitic assessment in splenic tissue was performed on day 45, 90 and 180 p.c. Initially, seven of the eight vaccinated monkeys developed infection (two to six amastigotes per 1000 cell nuclei), which resolved by day 180 p.c., while the eighth monkey had a parasite burden of 14 amastigotes per 1000 cell nuclei on day 45 p.c. and died on day 130 p.c. On the other hand, there was progressive infection in unvaccinated control animals and three out of four died between days 110 and 120 p.c., and one monkey, which had low parasite burden, died on day 178 p.c. Prior to challenge, there was an initial rise in antileishmanaial antibodies in the vaccinated group compared to the unvaccinated control group, which later came down to normal level, while it remained higher in the unvaccinated control group. An increasing pattern of antigen-specific proliferative responses and interferon-gamma level to the two antigens--autoclaved L. donovani (ALD) and ALM--was observed in vaccinated monkeys throughout the experiment. There was a good correlation between parasite burden and IFN-gamma level on days 90 and 180 p.c., indicating IFN-gamma response as a sensitive parameter of immune status. The findings suggest alum-precipitated ALM+BCG as a potential vaccine against visceral leishmaniasis and warrants clinical trials.

Recombinant hemagglutinin protein of rinderpest virus expressed in insect cells induces humoral and cell mediated immune responses in cattle

Rinderpest virus causes a highly contagious and often fatal disease in domestic and wild ruminants. The surface glycoproteins, hemagglutinin (H) and fusion (F) proteins of this enveloped virus are known to confer protective immunity in cattle. We have reported the generation of a recombinant baculovirus expressing H protein and studied its protective properties in cattle. In this report, we demonstrate that the recombinant baculovirus encoded H protein expressed in insect cells gets incorporated into extracellular baculovirus. Single administration of low doses of purified recombinant extracellular virus with or without adjuvant induces virus neutralizing antibody responses and bovine leukocyte antigen (BoLA) class II restricted helper T cell responses in cattle.

Mechanism of action of disease modifying anti-rheumatic agent, gold sodium thiomalate (GSTM)

GSTM has been used for long in the treatment of rheumatoid arthritis (RA). However, its mechanism of action is still poorly understood. In the last decade, tumor necrosis factor-alpha (TNF-alpha) has emerged as the major pro-inflammatory cytokine in the pathogenesis of RA. We studied the effect of GSTM on spontaneous and LPS-stimulated TNF-alpha production by human peripheral blood mononuclear cells (PBMCs) of normal volunteers. PBMCs were isolated from 20 normal volunteers and cultured in the presence of absence of lipopolysaccharide (LPS 10 ng/ml) and GSTM (1 microgram/ml). TNF-alpha level was measured using commercial enzyme-linked immunosorbent assay (ELISA) and reverse transcription-polymerase chain reaction (RT-PCR). The TNF-alpha response to LPS was heterogeneous. PBMCs of 24 subjects showed high LPS-stimulated TNF-alpha production (LPS-responsive group), whereas that of six individuals had low LPS-stimulated TNF-alpha production (LPS-non-responsive group). GSTM-stimulated spontaneous TNF-alpha production and inhibited LPS-stimulated TNF-alpha production in 16 of 24 (75%) individuals of LPS-responsive group and one of six individuals (17%) of LPS-non-responsive group. The suppression of TNF-alpha by GSTM was also demonstrated at the mRNA level. We conclude that there is a heterogeneity among normal population for TNF-alpha production in response to LPS, and GSTM inhibits LPS-stimulated TNF-alpha production, primarily in LPS responders. Further study is needed to establish the relationship between LPS responsiveness and GSTM suppression.

Simultaneous amplification of DNA and RNA virus using multiplex PCR system

A large number of disease-causing bacteria and viruses are being sequenced and PCR is increasingly used for the diagnosis of the diseases. We have designed a multiplex PCR system for hepatitis B virus (HBV), a DNA virus, and hepatitis E virus (HEV), an RNA virus. A modified technique has been standardized for simultaneous extraction of DNA and RNA, followed by a one-step RT-PCR/PCR.

Absence of Toll-like receptor 4 explains endotoxin hyporesponsiveness in human intestinal epithelium

BACKGROUND

The Toll protein in Drosophila regulates dorsal ventral patterning during embryogenesis, and participates in antibacterial and antifungal host defense. Mammalian homologues are termed Toll-like receptors and, to date, nine have been cloned (TLRI-9) in humans. They are characterized by extracellular leucine-rich repeats and a cytoplasmic domain similar to the interleukin 1 receptor. Both TLR2 and TLR4 recognize various bacterial cell wall components including lipopolysaccharide (LPS). This results in the activation of the NFkappaB pathway. Peripheral blood mononuclear cells (PBMCs) express both TLR2 and TLR4. The authors hypothesized that the expression of TLR 2 and TLR4 in human intestinal epithelial cells differs from PBMCs because of the abundance of LPS in the intestinal lumen.

METHODS

Epithelial cells were isolated from Caco-2 cells, fetal gut explants, and small bowel resection specimens using Hanks/ethylenediamine tetraacetic acid solution. PBMCs were used as positive controls. Ribonucleic acid (RNA) was isolated using the TRIzol method. Standard reverse transcription-polymerase chain reaction examined TLR2 and TLR4 messenger RNA (mRNA) expression. NFkappaB expression was determined using a luciferase reporter assay.

RESULTS

TLR2 mRNA was highly expressed in PBMCs and was present in all human intestinal epithelial cells. TLR4 mRNA was detected only in PBMCs. TLR4 is not present in epithelium from children with inflammatory bowel disease. In Caco-2 cells, significant NFkappaB activation in response to LPS occurred only in the presence of TLR4 introduced by complementary deoxyribonucleic acid transfection.

CONCLUSION

Absence of TLR4 is associated with endotoxin hyporesponsiveness of intestinal epithelial cells. TLR4 is not directly involved in inflammation of the intestinal epithelium. Although TLR2 is normally present in the epithelial cell, it plays a limited role in inflammation. It may be activated during conditions in which bacterial cell wall concentrations within the intestine are pathologically high.

Dietary regulation of intestinal gene expression

We are becoming increasingly aware of inherited genetic abnormalities as causes of disease. However, alterations in gene expression can also contribute to other disease processes. Recently it has been suggested that our environment may alter such genes and thus be a direct influence on disease. Diet is a potent mechanism for altering the environment of cells of most organs, particularly the gastrointestinal tract. This review addresses the influence of nutritional factors on intestinal gene regulation. These influences include insulin, which is not a dietary component but responds to dietary changes, and butyrate, a short chain fatty acid produced by normal intestinal flora. Manipulation of diet may be a means of treating intestinal disorders. Nutritional treatment therefore is also discussed in the light of its effect on gene expression.

Is immunoproliferative small intestinal disease uncommon in India?

Till date only three series of immunoproliferative small intestinal disease (IPSID) describing 22 patients have been reported from India. Seven patients with IPSID in two tertiary referral centers in India are included in the study. Diagnosis was based on typical clinical features [diarrhoea (7/7), weight loss (7/7), clubbing (6/7), fever (3/7), abdominal pain and lump (3/7)], biochemical evidence of malabsorption and duodenal biopsy findings. All patients were young males (mean age 29.8 +/- 11.8 years, range 17-53). Atypical features included gastric involvement (1/7), colonic involvement (1/7) and appearance of pigmented nails following anti-cancer chemotherapy (1/7) which disappeared six months after omitting doxorubin from chemotherapy regimen. Parasitic infestation was common. Ascaris lumbricoides (1/7), Giardia lamblia and hookworm (1/7), Strongyloides stercoralis and Trichuris trichura (1/7). In the latter patient S. stercoralis became disseminated after anti-malignant chemotherapy. One patient had gastric H. pylori infection. Four of the seven patients who were misdiagnosed as tropical sprue were treated with tetracycline. This raises doubt on efficacy of tetracycline alone in treatment of IPSID. One other patient was misdiagnosed and treated as intestinal tuberculosis. Early diagnosis and administration of chemotherapy may improve survival in this disease.

Cutting edge: C-C chemokine receptor 6 is essential for arrest of a subset of memory T cells on activated dermal microvascular endothelial cells under physiologic flow conditions in vitro

Memory T cells (mTC) express multiple chemokine receptors (including CCR4 and CCR6) that may potentially be involved in their arrest on inflamed endothelia. Herein, we specifically addressed whether CCR6 is required for mTC to arrest on TNF-alpha-activated human dermal microvascular endothelial cells (HDMEC) in vitro under shear stress conditions. Recombinant liver and activation-regulated chemokine (LARC)/CCL20 (a CCR6 ligand) induced firm arrest of cutaneous lymphocyte Ag(+) mTC in a flow chamber system using purified substrates. Strikingly, desensitization of CCR6 with LARC, but not thymus and activation-regulated chemokine/CCL17 or secondary lymphoid tissue chemokine/CCL21, caused a 50-75% decrease (p < 0. 001) in arrest of mTC on HDMEC, which was indistinguishable from the reduction observed when total mTC were treated with pertussis toxin (p > 0.5). CCR6-depleted mTC also had a markedly reduced ability to arrest on HDMEC. Our results suggest that LARC production by activated endothelial cells and CCR6 expression by mTC may be critical components in the pertussis toxin-sensitive arrest of mTC on activated HDMEC.