Advanced laboratory techniques for diagnosing Toxoplasma gondii encephalitis in AIDS patients: significance of intrathecal production and comparison with PCR and ECL-western blotting

The use of Toxoplasma gondii tachyzoites produced in HeLa cells adhered to Cytodex 1 microcarriers as antigen in serological assays: an application of microcarrier technology

Toxoplasma gondii can infect nearly all warm-blooded animals, including humans. In the laboratory diagnosis of toxoplasmosis, serological tests have importance in detecting antibody response. Traditionally T. gondii tachyzoites grown in vivo are being used as an antigen source in serological assays. Currently, tachyzoites produced in vitro are being tested as an antigen source in order to decrease animal use. Microcarrier technology allowed us to grow anchorage-dependent host cells on microcarrier suspension in short time and approximately 10 times more than traditional flask technique. The ability of T. gondii tachyzoites to grow in host cells adhered to microcarriers has not been analyzed yet. In this study, we aimed to develop a novel in vitro culture method to produce T. gondii tachyzoites abundantly using HeLa cells adhered to Cytodex 1 microcarriers. Initially, the growth of HeLa cells adhered to Cytodex 1 was analyzed using RPMI 1640, DMEM, and EMEM. Next, HeLa cells with a concentration of 1 × 10⁵ cells/ml and 2 × 10⁵cells/ml were adhered to Cytodex 1 and grown in spinner flasks. Then, T. gondii tachyzoites were inoculated with 1:1 and 2:1 cell:tachyzoite ratios to HeLa cells adhered to microcarriers in spinner flaks. During continuous production in spinner flasks, tachyzoites were harvested at the 2nd, 4th, and 7th day of culture and the quality of antigens produced from these tachyzoites were tested in ELISA and Western Blotting using sera of patients with toxoplasmosis. The optimization studies showed that finest HeLa inoculation value was 2 × 10⁵cells/ml using RPMI 1640, and the cell:tachyzoite ratio to obtain the highest tachyzoite yield (17.1 × 10⁷) was 1:1 at the 4th day of inoculation. According to the results of ELISA comparing HeLa cell and mouse derived antigens, the highest correlation with mouse antigen was achieved at the 4th day of HeLa cell culture with 1:1 HeLa:tachyzoite ratio (P < 0.0001). The sensitivity and specificity ratios of ELISA were 100%. In addition, Western blotting banding patterns of the antigen derived at the 4th day of HeLa cell culture with 1:1 HeLa:tachyzoite ratio was comparable with mouse derived antigen. Overall, this novel methodology can be an alternative source of antigen in diagnostic assays, decrease animal use for antigen production, and contribute to the solution of ethical and economic problems.

Equine Protozoal Myeloencephalitis: An Updated Consensus Statement with a Focus on Parasite Biology, Diagnosis, Treatment, and Prevention

Equine protozoal myeloencephalitis (EPM) remains an important neurologic disease of horses. There are no pathognomonic clinical signs for the disease. Affected horses can have focal or multifocal central nervous system (CNS) disease. EPM can be difficult to diagnose antemortem. It is caused by either of 2 parasites, Sarcocystis neurona and Neospora hughesi, with much less known about N. hughesi. Although risk factors such as transport stress and breed and age correlations have been identified, biologic factors such as genetic predispositions of individual animals, and parasite‐specific factors such as strain differences in virulence, remain largely undetermined. This consensus statement update presents current published knowledge of the parasite biology, host immune response, disease pathogenesis, epidemiology, and risk factors. Importantly, the statement provides recommendations for EPM diagnosis, treatment, and prevention.

IgG4 specific to Toxoplasma gondii excretory/secretory antigens in serum and/or cerebrospinal fluid support the cerebral toxoplasmosis diagnosis in HIV-infected patients

Cerebral toxoplasmosis is the most common neurological opportunistic disease manifested in HIV infected patients. Excretory/secretory antigens (ESA) are serological markers for the diagnosis of reactivation of the infection in HIV-infected patients with cerebral toxoplasmosis. Immunosuppressed patients develop high antibody titers for ESA. However, little is known about the humoral response for these antigens. The present study analyzed the profile of antibody recognition against ESA in comparison with tachyzoite lysate antigen (TLA) in 265 sera and 270 cerebrospinal fluid (CSF) samples from infected patients with Toxoplasma gondii and or HIV and in sera of 50 healthy individuals. The samples of sera and CSF were organized in 8 groups. The sera sample groups were: Group I - Se/CT/AIDS (patients with cerebral toxoplasmosis/AIDS) with 58 samples; Group II - Se/ONinf/AIDS/PosT (patients with AIDS/other neuroinfections/positive toxoplasmosis) with 49 samples; Group III - Se/ONinf/AIDS/NegT (patients with AIDS/other neuroinfections/negative toxoplasmosis) with 58 samples; Group IV - Se/PosT/NegHIV (individuals with asymptomatic toxoplasmosis/negative HIV) with 50 samples and Group V - Se/NegT/NegHIV (healthy individuals/negative toxoplasmosis and HIV) with 50 samples. The CSF sample groups were: Group VI - CSF/CT/AIDS (patients with cerebral toxoplasmosis/AIDS) with 99 samples; Group VII - CSF/ONinf/AIDS/PosT (patients with AIDS/other neuroinfections/positive toxoplasmosis) with 112 samples, and Group VIII - CSF/ONinf/AIDS/NegT (patients with AIDS/other neuroinfections/negative toxoplasmosis) with 59 samples. Levels of IgM, IgA, IgE, IgG and subclasses were determined by ELISA against TLA and ESA antigens. IgM, IgA or IgE antibodies against ESA or TLA were not detected in sera from patients with toxoplasmosis suggesting that all patients were in chronic phase of the infection. High levels of IgG1 against TLA were found in sera samples from groups I, II and IV and in CSF samples from groups VI and VII; whereas IgG2, IgG3 and IgG4 levels were not detected in the same sera or CSF sample groups. However, patients from groups I and VI, that had tachyzoites circulating in blood and CSF respectively, produced a mix of IgG1 and IgG4 antibodies against ESA. IgG2 against ESA were predominant in serum from patients with the latent (non-active) T. gondii infection/HIV negative and in CSF samples from patients with other neuroinfections and positive toxoplasmosis (groups IV and VII, respectively). IgG4 levels against ESA were found to be significantly (P<0.05 and P<0.005) higher in patients with cerebral toxoplasmosis (groups I and VI, respectively) in comparison with groups II, IV and VII. This data suggest that IgG4 can be valuable for supporting the diagnosis of focal brain lesions, caused by T. gondii infection, in HIV-infected patients. This approach might be useful, mainly when molecular investigation to detect parasites is not available.

Legionellosis presenting as singultus and external ophthalmoplegia

We report a 71-year-old man with legionellosis, who presented with abducens nerve palsy, singultus, confusion, memory impairment, ataxia, and hyporeflexia. Legionella pneumonia was diagnosed on the basis of detection of Legionella pneumophila antigen in the urine. The cerebrospinal fluid was negative for the antigen and antibody, but an oligoclonal band was detected, and the IgG index was elevated. It was speculated that an undetermined immune-mediated mechanism had contributed to the development of the neurological manifestations.

Utility of molecular and serodiagnostic tools in cerebral toxoplasmosis with and without tuberculous meningitis in AIDS patients: A study from South India

Background:

Antemortem diagnosis of cerebral toxoplasmosis, the second most common opportunistic infection (OI) in HIV-infected individuals in developing countries is a challenge.

Materials and Methods:

Toxoplasma gondii (T.gondii) -specific serology and nested polymerase chain reaction (nPCR) were evaluated in sera and ventricular/lumbar cerebrospinal fluid (CSF) of 22 autopsy confirmed cases of cerebral toxoplasmosis with HIV and 17 controls. Frequency of concomitant T.gondii infection was investigated in 17 cases of HIV-associated tuberculous meningitis (TBM).

Results:

The sensitivity, specificity, and positive and negative predictive values of T. gondii IgG on CSF (ventricular and lumbar) and sera was 100% in histology proven cerebral toxoplasmosis (concentrations: 258 ± 50, 231 ± 36, and 646 ± 243 IU/mL, respectively); majority (94%) being high avidity type, suggesting reactivation/reinfection. The sensitivity of B1 nPCR was 100% on ventricular CSF, whereas it was only 77% on lumbar CSF. Based on histology, nPCR, and IgG serology, T. gondii co-infection with TBM was observed in 65% (11/17) of cases.

Discussion and Conclusion:

CSF IgG serology and nPCR are tests with high sensitivity and specificity for the diagnosis of cerebral toxoplasmosis. TBM and cerebral toxoplasmosis can coexist and should be considered in the background of HIV infection in developing countries.

Diagnosis of Toxoplasma gondii infection after allogeneic stem cell transplant can be difficult and requires intensive scrutiny

Infectious complications remain a major problem after allogeneic hematopoietic stem cell transplant (HSCT). Specifically Toxoplasma gondii infection is a life-threatening condition in immunocompromised patients. In order to highlight the difficulties in obtaining an early and definitive diagnosis, we report three cases of toxoplasmosis after HSCT for hematologic malignancies: two cases of T. gondii retinochoroiditis, and one case of encephalitis. All patients had unrelated donors and received antithymocyte globulin; none had received trimethoprim/sulfamethoxazole prophylaxis. Toxoplasmosis occurred early post-transplant and diagnosis was obtained by real-time PCR. In one case, the correct diagnosis could only be established by PCR analysis of a retinal biopsy specimen. Rapid diagnosis--by invasive approaches--and an immediate onset of antiparasite treatment are crucial to avoid disseminated and often lethal Toxoplasma infections in the post-transplant period. Post-transplant prevention strategies and treatment to control advanced infection in this setting are discussed.

Toxoplasma gondii infection and cerebral toxoplasmosis in HIV-infected patients

Cerebral toxoplasmosis is a major cause of morbidity and mortality among HIV-infected patients, particularly from developing countries. This article summarizes current literature on cerebral toxoplasmosis. It focuses on: Toxoplasma gondii genetic diversity and its possible relationship with disease presentation; host responses to the parasite antigens; host immunosupression in HIV and cerebral toxoplasmosis as well as different diagnostic methods; clinical and radiological features; treatment; and the direction that studies on cerebral toxoplasmosis will likely take in the future.

[Spinal cord toxoplasmosis in HIV infection]

We report the case of an atypical localization of a spinal cord "toxoplasmic abscess". The 46-year-old patient, HIV-1 positive, was admitted for acute urine retention and gait disorders. MRI revealed a T12-L1 medullary lesion suggesting a tumoral, inflammatory and infectious pathology. The radiological aspect and immunosuppression lead to the initiation of a treatment against Toxoplasma gondii, following the same treatment principles as for cerebral toxoplasmosis. The diagnosis can only be proved by data from autopsy or surgical biopsy, but toxoplasmosis PCR on CSF seems to be an interesting alternative to confirm the diagnosis. According to the literature, PCR is not sensitive enough as a diagnostic tool. Improvement after treatment supported the diagnosis confirmed by PCR.

Molecular diagnosis of Toxoplasma gondii infection in cerebrospinal fluid from AIDS patients

Background

Toxoplasmic encephalitis (TE) is one of the most common opportunistic infections in immunocompromised patients. In Cuba, despite the highly active antiretroviral therapy, TE is still the most important cause of cerebral mass lesions in patients infected with the human immunodeficiency virus (HIV). The detection of Toxoplasma gondii by PCR may facilitate the diagnosis and follow-up of TE in acquired immunodeficiency syndrome (AIDS) patients by direct identification of parasite DNA in clinical samples. The aim of the present study was to evaluate a rapid PCR method using the B1 gene to detect T. gondii in cerebrospinal fluid (CSF) samples from patients with suspected TE.

Methods

CSF samples from AIDS and HIV-negative patients were analyzed. Patients were divided into two groups according to the Centre for Disease Control and Prevention (CDC) criteria for AIDS-related TE: AIDS patients with suspected neurotoxoplasmosis and AIDS and HIV-negative patients with other confirmed neurological diseases but no suspicions of TE. Predictive values, diagnostic accuracy, sensitivity and specificity of the PCR B1 method were calculated.

Results

The results obtained from 190 patients showed that this assay has a good sensitivity and specificity (83.3% and 95.7%, respectively) for the diagnosis of TE in AIDS patients.

Conclusion

PCR using the B1 gene and B22/B23 set of primers is a single, rapid and reliable method that may be valuable for discrimination between toxoplasmosis and other central nervous system (CNS) diseases.

Antibody index and specific antibody quotient in horses after intragastric administration of Sarcocystis neurona sporocysts

OBJECTIVE

To investigate the use of a specific antibody index (AI) that relates Sarcocystis neurona-specific IgG quotient (Q(SN)) to total IgG quotient (Q(IgG)) for the detection of the anti-S neurona antibody fraction of CNS origin in CSF samples obtained from horses after intragastric administration of S neurona sporocysts.

ANIMALS

18 adult horses.

PROCEDURES

14 horses underwent intragastric inoculation (day 0) with S neurona sporocysts, and 4 horses remained unchallenged; blood and CSF samples were collected on days - 1 and 84. For purposes of another study, some challenged horses received intermittent administration of ponazuril (20 mg/kg, PO). Sarcocystis neurona-specific IgG concentrations in CSF (SN(CSF)) and plasma (SN(plasma)) were measured via a direct ELISA involving merozoite lysate antigen and reported as ELISA units (EUs; arbitrary units based on a nominal titer for undiluted immune plasma of 100,000 EUs/mL). Total IgG concentrations in CSF (IgG(CSF)) and plasma (IgG(plasma)) were quantified via a sandwich ELISA and a radial immunodiffusion assay, respectively; Q(SN), Q(IgG), and AI were calculated.

RESULTS

Following sporocyst challenge, mean +/- SEM SN(CSF) and SN(plasma) increased significantly (from 8.8 +/- 1.0 EUs/mL to 270.0 +/- 112.7 EUs/mL and from 1,737 +/- 245 EUs/mL to 43,169 +/- 13,770 EUs/mL, respectively). Challenge did not affect total IgG concentration, Q(SN), Q(IgG), or AI.

CONCLUSIONS AND CLINICAL RELEVANCE

S neurona-specific IgG detected in CSF samples from sporocyst-challenged horses appeared to be extraneural in origin; thus, this experimental challenge may not reliably result in CNS infection. Calculation of a specific AI may have application to the diagnosis of S neurona-associated myeloencephalitis in horses.

Polymerase chain reaction and Goldmann-Witmer coefficient analysis are complimentary for the diagnosis of infectious uveitis

PURPOSE

To determine the relative contribution of the analysis of intraocular antibody production and the polymerase chain reaction (PCR) in aqueous humor (AH) to the diagnosis of infectious uveitis.

DESIGN

Retrospective case-control study.

METHODS

Paired AH and serum samples from 230 patients suspected of infectious uveitis were examined for intraocular antibody production against herpes simplex virus (HSV), varicella zoster virus (VZV), and Toxoplasma gondii by calculating the Goldmann-Witmer coefficient (GWC). In addition, AH samples were investigated by real-time PCR to determine the presence of microbial DNA.

RESULTS

Positive results were obtained in 54 cases (23%): 13 HSV (24%), 16 VZV (30%), and 25 T gondii (46%). Of these, 23 (43%) were positive for both GWC and PCR, 26 (48%) only for GWC, and 5 (9%) only for PCR. With PCR as the sole diagnostic approach, a correct diagnosis of the infectious etiology would have been missed in 34% of cases for the herpes viruses and in 64% for T gondii. Analysis of the relationship between a positive laboratory diagnosis and the time of sampling after onset of ocular disease demonstrated that intraocular antibody production was found throughout the course of the diseases. Viral DNA was more readily detected early in infection. In contrast, T gondii nucleic acid was not detected until 3 weeks after onset of ocular disease.

CONCLUSIONS

Analysis of intraocular antibody production contributed considerably to the etiological diagnosis of infectious uveitis, most notably of ocular toxoplasmosis early after onset of disease. Therefore, both PCR and GWC determination might be performed for comprehensive diagnosis of intraocular infections.

Detection of anti-Leishmania immunoglobulin G antibodies in urine specimens of dogs with leishmaniasis

For years, anti-Leishmania immunoglobulin G (IgG) antibodies have been detected in the sera of dogs living in areas of leishmaniasis endemicity. They have also been found in the aqueous humor and cerebrospinal fluid. In contrast, a review of the literature failed to identify the detection of anti-Leishmania antibodies in urine samples from dogs with leishmaniasis. Ninety-five dog urine samples were examined for the presence of anti-Leishmania antibodies by using a protein A enzyme-linked immunosorbent assay (ELISA). Twenty additional urine samples were collected from healthy dogs as controls. An IgG2 ELISA was performed on 26 urine samples found positive by the protein A ELISA. Twenty-three urine samples found positive to anti-Leishmania antibodies were tested for the local production of anti-Leishmania antibodies in the urinary tract by means of the urine antibody coefficient. Ten urine samples (and the corresponding serum samples) were compared by Western blot (WB) analysis. Thirty-five out of the 95 urine samples were found positive, 57 were found negative, and 3 were found inconclusive for antibody detection by the protein A ELISA. A high correlation between protein A and IgG2 levels was found in positive urine samples. Anti-Leishmania antibodies were present in the urine of dogs that had leishmaniasis, urinary protein/creatinine (U P/C) ratios of greater than one, and normal urinary sediment. A statistically significant correlation was observed between the U P/C ratios and the levels of anti-Leishmania antibodies in positive urine samples. In general, WB analysis and the urine antibody coefficient suggested that the presence of anti-Leishmania antibodies in urine was the consequence of an impairment of filtration of the glomerular barrier. However, in some dogs, WB analysis could be interpreted as suggesting that the presence of anti-Leishmania antibodies was caused, to a lesser extent, by local antibody production in the urinary tract. Antibody detection in urine could be a noninvasive method for leishmaniasis diagnosis and prognosis in dogs with glomerulonephropathies.

Viliuisk encephalomyelitis: intrathecal synthesis of oligoclonal IgG

Viliuisk encephalomyelitis (VE) is a neurodegenerative disorder expressed as subacute meningo-encephalitis progressing to a more prolonged pan-encephalitic syndrome with a fatal outcome within 1 to 10 years. Some patients survive to a steady state of global dementia and severe spasticity that may last for over 20 years. Multiple micronecrotic foci surrounded by inflammatory infiltrates are observed throughout the cerebral cortex and other gray matter areas. Infectious etiology of VE is strongly suspected, but the causative agent has not been identified. We conducted a search for assays that might be helpful for VE diagnosis and established for the first time that the majority of patients with definite VE show evidence for intrathecal IgG synthesis correlating with the clinical manifestations of the disease. This indicates that the detection of oligoclonal IgG banding in the cerebrospinal fluid is a valuable diagnostic assay for VE. Implications of these findings for a possible etiology of VE are discussed.

Molecular diagnosis of toxoplasmosis

Toxoplasmosis is an anthropozoonotic disease endemic world-wide, caused by the apicomplexan Toxoplasma gondii. Although the course of infection is generally benign, it can cause significant morbidity and mortality in the developing fetus and in immunocompromised individuals. Biological diagnosis classically relies upon serology and direct detection of the parasite by inoculation to laboratory animals. In the past decade, the use of the polymerase chain reaction (PCR) has made a significant improvement in both the prenatal diagnosis of congenital toxoplasmosis and the detection of acute disease in the immunocompromised patient. Nevertheless, like many 'in-house' PCR assays, the PCR-Toxoplasma suffers from lack of standardization and variable performance according to the laboratory. A wide variety of primers has been used in different assays, but few comparative tests have been performed. Moreover, in contrast to other parasitic diseases, PCR-Toxoplasma has not yet attained a sufficient level of sensitivity, regardless of the clinical condition considered. These drawbacks are discussed, together with the undoubted gain that PCR has brought to this difficult diagnosis.

Efficacy of a novel reverse transcriptase-polymerase chain reaction (RT-PCR) for detecting Toxoplasma gondii bradyzoite gene expression in human clinical specimens

A reverse transcriptase-polymerase chain reaction (RT-PCR) assay, was performed to evaluate the transcription degree of bradyzoite- or tachyzoite-specific genes of Toxoplasma gondii on cerebrospinal fluid (CSF) specimens from AIDS patients with toxoplasmic encephalitis (TE), and to distinguish an asymptomatic latent infection from a reactivated disease. This method was compared with nested DNA amplification (n)-PCR. The mRNA expression of the representative T. gondii cystic matrix (MAG1) or bradyzoite-specific (SAG4) genes was investigated on CSF obtained from AIDS patients with first episode (no. 11) or relapse (no. 8) of TE. The mRNA expression of tachyzoite-specific (SAG1) gene was also studied. New designed oligonucleotide primers and probes, which identify a 212 bp fragment inside to the open reading MAG1 sequence, were employed in both RT-PCR and n-PCR assays. Oligo-dT primed cDNA synthesis appeared a suitable method for subsequent analysis by n-PCR. RT-PCR has been shown to be more sensitive and specific than n-PCR. MAG1 and SAG4 gene expression was detected in 8 (100%) and 6 (75%) patients with TE relapses, respectively, while SAG1 detected 7 (63%) patients with TE first episode. These findings suggest that RT-PCR method is able to identify the bradyzoite stage of T. gondii especially in patients who are at risk for TE relapse.

Principles of molecular microbiology testing methods

Molecular testing methods have the potential to replace many conventional microbiology laboratory assays. Recent refinements in technology have resulted in more user-friendly testing platforms. These platforms are automated and have lowered risks for contamination, decreased costs, and are faster than older platforms. The success of these technologies depends on their successful application to patient care. Quality issues include appropriate specimens for analysis, performance characteristics of different analytical methods, optimal specimen processing, the effects of PCR inhibitors, and false-positive results caused by contaminating nucleic acids. Quality control guidelines for molecular microbiologic diagnostic assays are in their infancy and require further development. Additionally, the problem of "too much" sensitivity (brought on by the extreme sensitivity of these techniques coupled with the potential presence of small numbers of pathogenic organisms in asymptomatic individuals) should be considered. Potential problems when monitoring therapy (because molecular detection techniques do not generally have the ability to determine whether an organism is dead or alive) can also occur. Cost-effective test use, pathogen- or disease-targeted algorithms, and standardized methods will be necessary for the true value of these technologies to be realized. This is especially important, because, unlike traditional culture methods, most molecular microbiology methods are pathogen-specific. Clinicians familiar with the reasons why "pan-culture" (i.e., requesting all culture possibilities at once) is inadvisable should not use the same irrational approach when requesting molecular tests. The clinical usefulness of molecular testing will be maximized as targeted algorithms are developed and an understanding of molecular test ordering patterns is realized. Laboratory technicians and physicians must continue to apply and combine theories of traditional microbiology, clinical chemistry, and general medicine to the understanding and application of molecular diagnostics.

Assessment of HIV-intrathecal humoral immune response in AIDS-related neurological disorders

Intrathecal synthesis of IgG directed to HIV antigens was investigated by antibody specific index (ASI), affinity-mediated immunoblot (AMI) and Western blot (WB) assay in a group of 88 AIDS patients of which 28 with HIV-associated neurological disorders (HAND), 13 without associated neurological disorders (WAND) and 47 with non-HIV-associated neurological disorders (non-HAND). CD4+ count was above 50 cells/mm3 (CD4+>50) in 30 and below 50/mm3 (CD4+<50) in 58 patients, respectively. A significantly higher frequency for CSF complete anti-gag profile (p<0.001), and for HIV-specific oligoclonal patterns ("mixed" pattern=p<0.01) was observed in HAND as compared to patterns from the other clinical groups. A decrease in complete anti-env, anti-pol and anti-gag reactivity was present in CSF of patients with CD4+<50 as compared to those with CD4+>50. Our findings suggest that AIDS appears to be characterized by an anti-HIV intrathecal humoral immune response which is principally directed to env products with a prevalence of oligoclonal patterns and CSF complete anti-gag profile in HIV-associated neurological involvement.

Quantitative detection of Toxoplasma gondii DNA in human body fluids by TaqMan polymerase chain reaction

OBJECTIVE

A new quantitative polymerase chain reaction (real-time PCR) was designed to detect Toxoplasma DNA in human body fluid samples.

METHODS

Real-time fluorescence detection of amplification product formation on the basis of the TaqMan-System was established with Toxoplasma 18S rDNA as a target gene.

RESULTS

The method provides a high sensitivity comparable to conventional nested PCR procedures and generates quantitative data when detecting toxoplasmic DNA in human blood, cerebrospinal or amniotic fluid. Moreover, data were obtained investigating blood samples from an immunocompromised patient with reactivated toxoplasmosis after allogeneic bone marrow transplantation, monitoring the therapeutic effect.

CONCLUSIONS

The potential application of this method to detect Toxoplasma DNA in body fluids and to follow the development of parasitemia under therapy could be demonstrated.

Evidence of cerebrospinal fluid free kappa light chains in AIDS patients with Toxoplasma gondii encephalitis

Cerebrospinal fluid (CSF) free light chains of kappa or lambda (FLC kappa/lambda) type were investigated by affinity mediated blotting technique (AMI) and ELISA in 28 patients of which nine with AIDS and Toxoplasma gondii encephalitis (AIDS, TE), 11 with AIDS with or without other CNS AIDS-related opportunistic infections (non-TE AIDS) and eight control patients with or without inflammatory neurological disorders (control group). CSF restricted oligoclonal FLC bands either of k or lambda isotype or both were found by AMI in 18 (90%) out of 20 AIDS patients, while a CSF pattern predominantly characterized by FkappaLC rather than FlambdaLC was observed in eight (88.8%) out of nine TE patients. No FLC components were detected in the matched sera of TE or non-TE AIDS patients or in the CSF and sera from control group. The anti-parasite-specific FkappaLC CSF/serum mean levels and the T. gondii-specific FkappaLC index values were found by ELISA to be significantly more elevated in TE patients when compared to non-TE AIDS or control group. These findings suggest that the increased production of T. gondii-specific FkappaLC could provide insights into pathogenesis of reactivated TE in immunocompromised patients and may have important diagnostic usefulness.

Early aqueous humor analysis in patients with human ocular toxoplasmosis

To evaluate the diagnostic sensitivity of a panel of laboratory tests for ocular toxoplasmosis performed at the time of presentation, paired samples of aqueous humor and serum were collected from 49 consecutive episodes of ocular toxoplasmosis with a clinical course of less than 3 weeks. Total immunoglobulin G (IgG) and Toxoplasma gondii-specific IgG, IgM, and IgA were quantified by enzyme-linked immunosorbent assay. The avidity of T. gondii-specific IgG was determined, and DNA extracted from aqueous humor was amplified for detection of a glycoprotein B gene sequence of T. gondii. The diagnosis was confirmed for 73% (36 of 49) of the patients; this rate rose to 79.5% if data from a later analysis of aqueous humor derived from five of the negative patients were included. The analysis of serum (detection of T. gondii-specific IgM and analysis of consecutive serum samples) alone did not contribute to the diagnosis. Calculation of local antibody production lacked diagnostic sensitivity when it was determined less than 3 weeks after the manifestation of clinical symptoms (28 of 49 patients [57%]), but this rose to 70% after an analysis of a second aqueous humor sample. The antibody avidity index attained diagnostic significance in only 8 of 43 instances (19%), and T. gondii DNA was amplified from no more than 6 of 39 (16%) aqueous humor samples. However, T. gondii-specific IgA was found within the aqueous humors of 11 of 43 patients (26%); measurement of the T. gondii-specific IgA level thus contributed substantially to the diagnostic sensitivity of the laboratory tests.