Comparison of PCR, capture ELISA and immunoblotting for detection of Toxoplasma gondii in infected mice

Molecular evidence of toxoplasmosis in people living with HIV in Pakistan

BACKGROUND

Toxoplasma gondii is a zoonotically important parasite infecting almost all vertebrates. The parasite can easily infect humans through the fecal-oral route, particularly immunocompromised individuals, and children. Due to lack of epidemiological data regarding the occurrence of Toxoplasma gondii in people living with HIV in Pakistan, the present study was designed to estimate the prevalence of Toxoplasma gondii in people living with HIV.

METHODS

Briefly, 384 blood samples were randomly collected from people living with HIV registered under Punjab AIDS Control Program. DNA of all samples was extracted and the 18S rRNA gene of T. gondii was amplified through polymerase chain reaction (PCR) by using genus-specific primers. The amplicons were spread on 1.5% agar rose gel and visualized under gel documentation system. Then the amplicons were purified from the gel and subjected to sequence and phylogenetic analysis.

RESULTS

Overall prevalence of T. gondii was observed as 23.96%. The prevalence of T. gondii was significantly (p <0.05) higher in females and in middle age group (26-40 years). Similarly, the prevalence was significantly (p <0.05) higher in people with poor socioeconomic status, symptomatic patients, drugs users and people using unfiltered water for drinking. Furthermore, bodyweight (46-70 kg) and dry seasons also significantly (p <0.05) affected the prevalence of T. gondii.

CONCLUSIONS

Our findings illustrated a high infection rate of toxoplasmosis in people living with HIV which could be a significant cause of mortality. More studies need to be conducted for other opportunistic infections caused by parasites and other pathogens.

Detection of Toxoplasma gondii infection in semen of rams used for natural mating in commercial sheep farms in Tunisia

Toxoplasmosis, a parasitic infection, disrupts sexual functions resulting in decline in reproductive and economic performance in sheep. Lacking discernible symptoms, toxoplasmosis is difficult to detect and diagnose in infected animals. Here, to estimate the prevalence of natural infection by Toxoplasma gondii, we used PCR to amplify and detect T. gondii DNA in semen from 92 rams of three breeds from four regions in Tunisia and seroprevalence was determined using a commercial ELISA kit. From the PCR amplifications, 51.09 ± 10.21% of the rams were tested positive for T. gondii with an overall seroprevalence of 39.13 ± 9.97%. Risk factors including ram location and number of accomplished mating seasons significantly (p < .05) affected the sero- and molecular prevalence of T. gondii in semen but, there was a fair concordance between sero- and molecular prevalence (Kappa = 0.33). Sequences of T. gondii from five positive samples were 100% identical (same haplotype). Comparison of these sequences with those archived at the GenBank showed a sequence similarity range between 95 and 100%. The haplotype defining the five Tunisian sequences was similar to the one observed in chicken, cats, European pole cat and humans from Brazil, St Kitts and Nevis, Great Britain and Tunisia, respectively. This indicates its wide geographic distribution and non-species specificity. Our findings suggest a high prevalence of toxoplasmosis in Tunisian matting rams; further studies concerning its venereal transmission capacity are needed prior to recommending a systematic screening of T. gondii DNA in rams' semen used for both natural breeding and artificial insemination.

Advantages of bioconjugated silica-coated nanoparticles as an innovative diagnosis for human toxoplasmosis

Nanotechnology is a promising arena for generating new applications in Medicine. To successfully functionalised nanoparticles for a given biomedical application, a wide range of chemical, physical and biological factors have to be taken into account. Silica-coated nanoparticles, (SiO2NP) exhibit substantial diagnostic activity owing to their large surface to volume ratios and crystallographic surface structure. This work aimed to evaluate the advantage of bioconjugation of SiO2NP with PAb against Toxoplasma lyzate antigen (TLA) as an innovative diagnostic method for human toxoplasmosis. This cross-sectional study included 120 individuals, divided into Group I: 70 patients suspected for Toxoplasma gondii based on the presence of clinical manifestation. Group II: 30 patients harboring other parasites than T. gondii Group III: 20 apparently healthy individuals free from toxoplasmosis and other parasitic infections served as negative control. Detection of circulating Toxoplasma antigen was performed by Sandwich ELISA and Nano-sandwich ELISA on sera and pooled urine of human samples. Using Sandwich ELISA, 10 out of 70 suspected Toxoplasma-infected human serum samples showed false negative and 8 out of 30 of other parasites groups were false positive giving 85.7% sensitivity and 84.0% specificity, while the sensitivity and specificity were 78.6% and 70% respectively in urine samples. Using Nano-Sandwich ELISA, 7 out of 70 suspected Toxoplasma-infected human samples showed false negative results and the sensitivity of the assay was 90.0%, while 4 out of 30 of other parasites groups were false positive giving 92.0% specificity, while the sensitivity and specificity were 82.6% and 80% respectively in urine samples. In conclusion, our data demonstrated that loading SiO2 nanoparticles with pAb increased the sensitivity and specificity of Nano-sandwich ELISA for detection of T.gondii antigens in serum and urine samples, thus active (early) and light infections could be easily detected.

Evaluation of Toxoplasma gondii soluble, whole and excretory/secretary antigens for diagnosis of toxoplasmosis by ELISA test

The present study was performed to compare the soluble, whole and excretory/secretary antigens of Toxoplasma gondii (RH strain) in diagnosis of toxoplasmosis by ELISA method. Tachyzoites of T. gondii, RH strain were injected in intra-peritoneal cavity of BALB/c mice, after 4 days tachyzoites were harvested by peritoneal washing of the mice. For soluble antigen, exudates were centrifuged and sediment sonicated and then centrifuged at 4 °C, 1 h, supernatant collected and density of protein determined by Bradford method. For whole antigen after collecting, washing and centrifuging of peritoneal fluid the tachyzoites sediment was counted. In excretory/secretary antigen 1.5 × 10⁸ tachyzoites were transferred in 1 ml tube of saline and incubated under mild agitation and after centrifuging, supernatant was collected and protein density determined by Bradford method. 176 human serum samples were evaluated for T. gondii IgG antibody with prepared antigens, and finally serum samples were evaluated by commercial ELISA kit (Trinity, USA) which was considered as gold standard method. In this study sensitivity and specificity of prepared antigens compared with commercial kit in ELISA method. Sensitivity and specificity of soluble antigen was 91.4 and 74.5 %, in whole antigen these parameters were 77.1 and 77.3 % and in excretory/secretary antigen were 28.5 and 74.5 % respectively. Soluble antigen had high levels of sensitivity and specificity in ELISA method and the results were rather resemble to commercial kit (Trinity, USA).

Diagnosis of antigenic markers of acute toxoplasmosis by IgG avidity immunoblotting

To perform IgG avidity immunoblotting assay for detection of acute toxoplasmosis, 100 serum samples were collected from Tehran, Iran. The presence of Toxoplasma-specific IgG and IgM antibodies were checked by commercial Trinity kit. Samples were categorized in acute and chronic phases of Toxoplasma gondii infection according to IgG avidity ELISA. IgG avidity immunoblotting was performed, and antigenic bands with molecular weights of 22, 25, 28, 30, 32, 42, 44, 49, 55, 60, 66, 69, 88, 106, 130 and 157 kDa were recognized as low avidity markers. The most prevalent antigen for low avidity was p22. It is concluded that IgG avidity immunoblotting could distinguish acute and chronic phases of T. gondii infection.

Hedgehogs and sugar gliders: respiratory anatomy, physiology, and disease

This article discusses the respiratory anatomy, physiology, and disease of African pygmy hedgehogs (Atelerix albiventris) and sugar gliders (Petaurus breviceps), two species commonly seen in exotic animal practice. Where appropriate, information from closely related species is mentioned because cross-susceptibility is likely and because these additional species may also be encountered in practice. Other body systems and processes are discussed insofar as they relate to or affect respiratory function. Although some topics, such as special senses, hibernation, or vocalization, may seem out of place, in each case the information relates back to respiration in some important way.

Management of bilateral uveitis in a Toxoplasma gondii-seropositive cat with histopathologic evidence of fungal panuveitis

A 5‐year‐old, neutered male Domestic Short‐haired cat was referred with a 5‐month history of anterior uveitis and cataract in the right eye. Clinical examination confirmed anterior uveitis and immature cataract in the right eye and chorioretinitis in the left eye. Ocular ultrasound showed a retinal detachment in the right eye. Diagnostic testing revealed elevated serum titers for Toxoplasma gondii. Anterior uveitis in the right eye and chorioretinitis in the left eye progressed, resulting in blindness despite a 21‐day course of clindamycin and aggressive topical medical management of uveitis. The right eye was enucleated and histopathologic evaluation of the globe revealed panuveitis and multiple organisms morphologically consistent with Histoplasma capsulatum. Systemic treatment with itraconazole was initiated. Vision returned after 3 months of treatment and complete resolution of the retinal hemorrhages with formation of a flat chorioretinal scar was noted after 6 months of therapy. Itraconazole was discontinued 7 months after starting therapy, at which time the funduscopic appearance of the chorioretinal scar had remained static for 1 month. The cat has remained visual without evidence of disease progression for 6 months following discontinuation of itraconazole.

Toxoplasmosis in a colony of sugar gliders (Petaurus breviceps)

Eleven of a group of 16 sugar gliders died acutely over a period of 2 to 3 weeks. Histopathologic examination revealed a protozoal infection with tachyzoites present in multiple organs, including the intestine, heart, brain, spleen, pancreas, adrenal gland, and kidney. Immunostaining confirmed disseminated toxoplasmosis. Marsupials are susceptible to toxoplasmosis. It was thought that the sugar gliders acquired the infection through foraging in wood chips used as a substrate that were contaminated with feline fecal material.

Development of a rapid polymerase chain reaction-ELISA assay using polystyrene beads for the detection of Toxoplasma gondii DNA

AIMS

To develop a rapid colourimetric assay for the detection of Toxoplasma gondii DNA using polystyrene beads as solid support.

METHODS AND RESULTS

A nested-polymerase chain reaction (PCR)-ELISA assay for the detection of T. gondii DNA was standardized by optimizing the hybridization time and probe concentration. Its detection threshold was then determined and compared with Southern blotting hybridization. These were found to be equivalent, but the PCR-ELISA-beads test is easier to perform and the turnaround time is much shorter than with Southern blot.

CONCLUSIONS

The PCR-ELISA-beads assay is a valuable tool for the detection of T. gondii DNA.

SIGNIFICANCE AND THE IMPACT OF THE STUDY

Our results demonstrate that this PCR-ELISA assay, using polystyrene beads, can be used as a routine diagnostic test for the detection of T. gondii in clinical laboratories.

Experimental model of congenital toxoplasmosis in guinea-pigs: use of quantitative and qualitative PCR for the study of maternofetal transmission

Maternofetal transmission of Toxoplasma gondii was assessed in pregnant guinea-pigs, with a gestational period of 65 +/- 5 days. A total of 56 female guinea pigs was infected by the intraperitoneal route (RH strain), by the oral or the intraperitoneal route (Prugniaud strain; PRU) or by the oral route (76K strain). Inoculation was performed 90 +/- 18 days or 30 +/- 9 days before the onset of gestation or 20 +/- 6 days or 40 +/- 6 days after. Gestational age was determined by a progesterone assay. Parasite loads (fetal brain and liver) were assessed by nested PCR and real-time PCR quantification on Light Cycler was performed with a SYBR Green I technique. The 76K strain appeared to be the most virulent in the model: the neonatal survival rate was 31%, in contrast to 53% and 68% for the PRU and RH strains, respectively. The percentage of survival of neonates for all strains taken together was lower after inoculation at 40 days' gestation (25%) than at 20 days' gestation (77%). Whatever the strain, maternofetal transmission determination was greater with nested PCR (54% for RH, 84% for PRU and 86% for 76K strains) than with real-time quantitative PCR (31% for RH, 66% for PRU and 76% for 76K strains). However, real-time quantitative PCR showed that neonatal parasite load was greater with the cystogenic strains (76K, PRU) and that high hepatic load (> 10000 parasites/g) was often associated with disease severity (11 of 12 cases). Therefore, this technique may provide an important element in understanding this congenital disease.