Evaluation of Rapid IgG4 Test for Diagnosis of Gnathostomiasis

Human gnathostomiasis is a parasitic disease caused by Gnathostoma nematode infection. A rapid, reliable, and practical immunoassay, named dot immuno-gold filtration assay (DIGFA), was developed to supporting clinical diagnosis of gnathostomiasis. The practical tool detected anti-Gnathostoma-specific IgG4 in human serum using crude extract of third-stage larvae as antigen. The result of the test was shown by anti-human IgG4 monoclonal antibody conjugated colloidal gold. The sensitivity and specificity of the test were both 100% for detection in human sera from patients with gnathostomiasis (13/13) and from healthy negative controls (50/50), respectively. Cross-reactivity with heterogonous serum samples from patients with other helminthiases ranged from 0 (trichinosis, paragonimiasis, clonorchiasis, schistosomiasis, and cysticercosis) to 25.0% (sparganosis), with an average of 6.3% (7/112). Moreover, specific IgG4 antibodies diminished at 6 months after treatment. This study showed that DIGFA for the detection of specific IgG4 in human sera could be a promising tool for the diagnosis of gnathostomiasis and useful for evaluating therapeutic effects.

Sandwich dot-immunogold filtration assay (DIGFA) for specific immunodiagnosis of active neuroangiostrongyliasis

Serological tests may yield false-negative results for specific antibodies detection before or at the early seroconversion phase. Tests that detect circulating antigens of Angiostrongylus cantonensis would therefore be of value in diagnosis to distinguish current or past infection. Here, a quick, easy to perform, portable and inexpensive diagnostic device for detection of 31-kDa A. cantonensis specific antigens had been developed. This sandwich dot-immunogold filtration assay (AcDIGFAAg), for detecting active angiostrongyliasis was produced using anti-A. cantonensis polyclonal antibody dotted on the nitrocellulose membrane as a capture agent and colloidal gold-labelled anti-31 kDa A. cantonensis antibody as a detection agent. A well-defined pink dot, indicating positivity, was seen readily by naked eye within 10-15 min. The AcDIGFAAg detected A. cantonensis-specific antigens in cerebrospinal fluid samples from 4 out of 10 serologically confirmed angiostrongyliasis cases and 2 out of 5 suspected cases with negative anti-A. cantonensis antibodies. Among the 19 patient sera with A. cantonensis infection, 2 showed positive reaction by AcDIGFAAg. No positive AcDIGFAAg reaction was observed in all the serum samples with other parasitic diseases, and the healthy controls. The present 'AcDIGFAAg' enables rapid qualitative detection of the specific 31-kDa antigens of A. cantonensis in clinical samples with potential for application even under resource-limited settings.

GRK5 promotes tumor progression in renal cell carcinoma

GRK5 is a multifunctional protein that is able to move within the cell in response to various stimuli to regulate key intracellular signaling from receptor activation, on plasmamembrane, to gene transcription, in the nucleus. Thus, GRK5 is involved in the development and progression of several pathological conditions including cancer. Here, we report an important tumor-promoting role for GRK5 in renal cell carcinoma (RCC). We investigated the expression pattern, clinical significance, and function of GRK5 in RCC. By using quantitative real-time polymerase chain reaction (qRT-PCR) and tissue microarray (TMA) immunohistochemistry (IHC), we first demonstrated that compared with paired adjacent nontumor (NT) tissues, RCC tissues presented with higher GRK5 expression. Moreover, we found that GRK5 upregulation was associated with poor clinical outcomes in RCC patients. In vitro, we found that GRK5 knockdown reduced viability, invasive ability, migratory ability, and decreased proportion of cells in S phase, with concomitant increase in G1 phase in RCC cell lines, while GRK5 overexpression promoted tumor cell proliferation, cell invasion, migration and increased proportion of cells in S phase, with concomitant decrease in G1 phase. Collectively, our findings describe the tumour-promoting role of GRK5 in RCC and thus provide molecular evidence for new therapeutic options in RCC.

Molecular phylogeography and genetic diversity of Angiostrongylus cantonensis and A. malaysiensis (Nematoda: Angiostrongylidae) based on 66-kDa protein gene

Angiostrongylus cantonensis is the main causative agent of human angiostrongyliasis. A sibling species, A. malaysiensis has not been unequivocally incriminated to be involved in human infections. To date, there is only a single report on the application of the partial 66-kDa protein gene sequence for molecular differentiation and phylogeny of Angiostrongylus species. Nucleotide sequences of the 66-kDa protein gene of A. cantonensis and A. malaysiensis from Thailand, as well as those of the laboratory strains of A. cantonensis from Thailand and Hawaii, A. cantonensis from Japan and China, A. malaysiensis from Malaysia, and A. costaricensis from Costa Rica, were used for the reconstruction of phylogenetic tree by the maximum likelihood (ML) method and the haplotypes by the median joining (MJ) network. The ML phylogenetic tree contained two major clades with a full support bootstrap value - (1) A. cantonensis and A. malaysiensis, and (2) A. costaricensis. A. costaricensis was basal to A. cantonensis and A. malaysiensis. The genetic distance between A. cantonensis and A. malaysiensis ranged from p = .82% to p = 3.27%, that between A. cantonensis and A. costaricensis from p = 4.90% to p = 5.31%, and that between A. malaysiensis and A. costaricensis was p = 4.49% to p = 5.71%. Both A. cantonensis and A. malaysiensis possess high 66-kDa haplotype diversity. There was no clear separation of the conspecific taxa of A. cantonensis and A. malaysiensis from different geographical regions. A more intensive and extensive sampling with larger sample size may reveal greater haplotype diversity and a better resolved phylogeographical structure of A. cantonensis and A. malaysiensis.

Evaluation of dot immunogold filtration assay (DIGFA) for rapid serodiagnosis of eosinophilic meningitis due to Angio-strongylus cantonensis (Nematoda: Metastrongyloidea)

Angiostrongylus cantonensis is the most frequent cause of eosinophilic meningitis in humans in Thailand and worldwide. Because of difficulty of recovering the Angiostrongylus larvae from infected patients, detection of parasite-specific antibodies is used to support clinical diagnosis. This study tested serum samples from eosinophilic meningitis patients and individuals at risk of infection with A. cantonensis to evaluate a recently developed simple and rapid dot-immunogold filtration assay (DIGFA) for detection of specific antibodies against A. cantonensis. Purified 31-kDa glycoprotein of A. cantonensis and protein A colloidal gold conjugate were employed to detect the 31-kDa anti-A. cantonensis antibody in patients sera from the parasite endemic areas of northeast Thailand. The results were compared with those obtained by dot-blot enzyme-linked immunosorbent assay (ELISA) with 31-kDa A. cantonensis antigen. The overall positivity rate of DIGFA and dot-blot ELISA for A. cantonensis infection in 98 clinically diagnosed cases from three highly endemic districts in Khon Kaen province were 39.79% and 37.75%, respectively. Among 86 sera of subjects at risk of infection with A. cantonensis, 24.41% were positive by DIGFA and 23.25% by dot-blot ELISA. There were good correlation between the visual grading of DIGFA and dot-blot ELISA in both groups of defined sera. DIGFA is as sensitive and specific as dot-blot ELISA for confirming eosinophilic meningitis due to A. cantonensis infection, with advantages of simplicity, rapidity and without the use of specific and expensive equipment, and can be used in field settings.

[Dot immuno-gold filtration assay in the diagnosis of suspected paragonimiasis and evaluation of chemotherapeutic effect]

OBJECTIVE

To evaluate the usefulness of dot immuno-gold filtration assay(DIGFA) for the diagnosis of Paragonimus infection.

METHODS

During 2003 to 2006, 72 cases suspected of paragonimiasis in Zhejiang Province were examined with DIGFA for rapid detection of specific antibodies against Paragonimus (Pw-DIGFA). The diagnosis was primarily established with the presence of antibodies, experience of ingesting raw freshwater crabs or crayfishes and clinical presentations. The cases were treated with praziquantel and followed-up at 3 and/or 6 months post-treatment. Antibody level in patients (pre- and post-treatment) were detected in parallel and analyzed comparatively by Pw-DIGFA and ELISA.

RESULTS

The result of detection by Pw-DIGFA was in agreement with that of ELISA. 28 of 72 cases were antibody positive and 44 cases were negative. Among the 28 positives, 26 cases had a history of eating raw freshwater crab or crayfishes and the other 2 cases drank freshwater from brook before. 21 cases showed paragonimiasis-related clinical symptoms such as low-grade fever, cough, or changes in image examination, while the other 7 cases showed only eosinophilia in peripheral blood (15%-70%). The mean absorbance values (A450) of positive sera, negative sera and normal sera tested by ELISA were 1.7361, 0.2973 and 0.2657 respectively. There was significant difference between the positive cases and the negative cases (t=12.047, P<0.01) and no significant difference between the negative cases and normal controls (t=1.919, P>0.05). At 3 month post-treatment, serum antibody in 5 cases whose clinical symptoms and physical signs relieved or disappeared decreased 2-5 titers and that of one case who relapsed with new signs increased by one titer. In Pw-DIGFA, the dot color of 5 cured cases showed a little weaker than that of pre-treatment and the relapsed case displayed similar response. At 6 month post-treatment, 7 sera of clinically cured cases showed significantly weaker response than that of pre-treatment. The antibodies of those sera dropped 3-6 titers.

CONCLUSION

Pw-DIGFA is of supplementary value for clinical diagnosis of paragonimiasis. Antibody detection by pre- and post-treatment using Pw-DIGFA shows potential for the evaluation of therapeutic effect.

Recombinant tegumental protein Shistosoma japonicum very lowdensity lipoprotein binding protein as a vaccine candidate against Schistosoma japonicum

A polyhistidine-tagged recombinant tegumental protein Schistosoma japonicum very lowdensity lipoprotein binding protein (SVLBP) from adult Schistosoma japonicum was expressed in Escherichia coli. The affinity purified rSVLBP was used to vaccinate mice. The worm numbers and egg deposition recovered from the livers and veins of the immunized mice were 33.5% and 47.6% less than that from control mice, respectively (p<0.05). There was also a marked increase in the antibody response in vaccinated mice: the titer of IgG1 and IgG2a, IgG2b in the vaccinated group was significantly higher than that in the controls (>1:6,400 in total IgG). In a comparison of the reactivity of sera from healthy individuals and patients with rSVLBP, recognition patterns against this parasite tegumental antigen varied among different groups of the individuals. Notably, the average titres of anti-rSVLBP antibody in sera from faecal egg-negative individuals was significantly higher than that in sera from the faecal egg-positives, which may be reflect SVLBP-specific protection. These results suggested that the parasite tegumental protein SVLBP was a promising candidate for further investigation as a vaccine antigen for use against Asian schistosomiasis.

[Protective immunity of the recombinant Schistosoma japonicum specific very low density lipoprotein binding protein as a vaccine candidate]

OBJECTIVE

To investigate the protective immunity against Schistosoma japonicum in mice immunized with recombinant specific very low density lipoprotein binding protein (SVLBP) and its potential as vaccine candidate.

METHODS

Recombinant SVLBP antigen was over-expressed under IPTG induction and purified by Ni-NTA affinity chromatography. C57BL/6 mice were immunized three times with purified reSVLBP complexed with Freund's adjuvant, at biweekly intervals. Then 35+/-1 cercariae of S. japonicum were given to each mouse by abdominal skin 10 days after the 3rd immunization. 45 days later, all mice were sacrificed to collect adult worms and count liver eggs. serum samples were collected before immunization and after challenge respectively, and were probed the antigen-specific antibodies using a panel of ELISAs.

RESULTS

The worm burden and the egg deposition in liver tissue were reduced by 33.4% and 47.6% respectively in the immunized group, in comparison with the adjuvant control group (P<0.05). Higher titer (>1:6 400) of total IgG was observed after challenge infection. The vaccinated mice developed significantly higher levels of IgG2a, IgG2b, IgG1 than those of control mice.

CONCLUSION

The recombinant tegumental SVLBP antigen could induce partial protection against S. japonicum infection. These data demonstrate the potential of SVLBP as a schistosome vaccine candidate.

Use of a recombinant Clonorchis sinensis pore-forming peptide, clonorin, for serological diagnosis of clonorchiasis

A recombinant pore-forming peptide of Clonorchis sinensis, clonorin, was evaluated for serodiagnostic reagent of clonorchiasis by enzyme-linked immunosorbent assay detecting IgG antibody. Recombinant clonorin showed 100% specificity and low sensitivity for sera of human clonorchiasis. In contrast, C. sinensis crude antigen revealed lower specificity and higher sensitivity than recombinant clonorin did. In sera of experimental rabbits, clonorin-specific IgG antibody was increased remarkably 8 weeks after the infection and retained around level of OD(490)=0.2 for 1 year. With excellent antigenic specificity, it is suggested that the recombinant clonorin can be used as an ingredient of the cocktail antigen for serodiagnosis of clonorchiasis from early stages of the infection.

Clonorchis sinensis: glutathione S-transferase as a serodiagnostic antigen for detecting IgG and IgE antibodies

Human Clonorchis sinensis infection is endemic in East Asian countries. Glutathione S-transferases (GSTs) are anti-oxidant enzymes found in all living creatures as well as in trematodes. In this study, we examined the recombinant 26kDa GST protein of C. sinensis (Cs26GST) for its serodiagnostic antigenicity toward IgG and IgE antibodies by ELISA and immuno-enhanced chemiluminescence, respectively. In IgG ELISA, recombinant Cs26GST showed 33.3% sensitivity and 100% specificity for trematode-infected human sera. In the case of the IgE antibody, recombinant Cs26GST showed 50.0% sensitivity and 93.2% specificity for clonorchiasis infection. We propose that the recombinant Cs26GST is a potent serodiagnostic antigen for detecting C. sinensis-specific IgG and IgE antibodies, and that it be best used as an antigenic cocktail in combination with other antigens.

Recombinant Paragonimus westermani yolk ferritin is a useful serodiagnostic antigen

A recombinant protein of Paragonimus westermani yolk ferritin was bacterially produced from a previously cloned complementary DNA and was used as an antigen for an enzyme-linked immunosorbent assay (ELISA) against paragonimiasis- and other helminth-infected sera to evaluate its serodiagnostic potential. The ELISA revealed that paragonimiasis westermani had 88.2% sensitivity and 100% specificity. The positive and negative predictive values of the ELISA were calculated to be 100% and 97.1%, respectively. Sera from cats experimentally infected with P. westermani began to produce immunoglobulin G antibodies against the yolk ferritin at 13 weeks after infection, which suggests that the corresponding antigen was derived from the vitellaria in accordance with maturation of P. westermani. These results indicate that the recombinant P. westermani yolk ferritin is a potent serodiagnostic reagent for paragonimiasis westermani from an early stage of the infection.

The effect of cobalt-60 irradiation on the infectivity of Toxoplasma gondii

Toxoplasma gondii cysts in the tissues of experimentally infected mice and pigs were irradiated with cobalt-60 at various doses and used to infect mice and kittens. Loss of parasite infectivity was confirmed following irradiation whereas control animals inoculated with non-irradiated infected tissues became infected. Experiments were repeated to calculate the minimal effective dose (MED) of irradiation to eradicate parasite infectivity. The MED for the Chinese NT strain and the American ME-49 and TS-2 strains of T. gondii cysts in mouse and pig tissues was approximately 0.6 kGy. The infectivity for mice of NT strain bradyzoites irradiated at a dose of 0.45 kGy was reduced 10,000-fold. Such irradiation may be valuable in practical operations to control T. gondii in pork products.

Studies on the use of cobalt-60 irradiation to control infectivity of Toxoplasma gondii cysts

Mouse brains harboring the Chinese NT strain of Toxoplasma gondii cysts were homogenized with normal saline and irradiated with cobalt-60 gamma rays at various doses. The homogenate was introduced intraperitoneally into NIH mice or per os into kittens. Loss of infectivity was confirmed according to the following criteria: no cyst found in mouse brain impression smears on the 50th day after inoculation; no oocyst found in feces of kittens 3-15 days after inoculation; subinoculation in mice and a negative IHA test. All bioassays, parasitological examinations and serological tests in the control group gave positive results. Activity of radioactive source: 10 KCi; uniform dosage: 1238 rad/min; dose range of irradiation: 0.1-1.0 KGy. Minimal effective dose of gamma rays to control infectivity of T. gondii cysts was 0.55 KGy. Infectivity of bradyzoites irradiated with gamma rays at a dose of 0.45 KGy decreased by 10,000 times. Minimal effective dose of gamma rays to control infectivity of American ME-49 and Ts-2 strain, is slightly higher (0.6KGy) than that of NT strain. These studies present useful data for practical use of cobalt-60 to control infectivity of T. gondii in meat products.