miRNA 511_5p is a potential biomarker for ocular toxoplasmosis

BACKGROUND

Ocular toxoplasmosis (OT) is a frequent clinical manifestation due to infection by Toxoplasma gondii. It is characterized by an inflammatory process involving macrophages activated by pro-inflammatory cytokines. The expression of microRNAs takes place during the inflammatory process and, among them, miRNA 511 regulates the activation of macrophages. This study evaluated the expression of miRNA 511_5p in patients with OT and healthy controls.

METHODS

A total of 361 patients from the Hospital de Base of Fundação Faculdade de Medicina de São José do Rio Preto were enrolled and divided into four groups: G1-patients with active ocular lesions and reagent serology for T. gondii; G2-patients with scars and reagent serology for T. gondii; G3-patients without ocular lesions or scars and reagent serology for T. gondii; G4-patients without ocular lesions or scars and non-reagent serology for T. gondii. All patients underwent clinical and laboratory evaluation to confirm the diagnosis of OT. Serology tests, RNA extraction and cDNA synthesis were performed.

RESULTS

The miRNA 511_5p levels were compared among the groups. The G1 group showed a high blood plasma concentration of miRNA 511_5p (mean 22.34) compared with the G2 (4.65), G3 (8.91) and G4 (3.52) groups (p<0.0001).

CONCLUSION

These data suggest that miRNA 511_5p has significant potential as a biomarker for OT.

Molecular detection of Leishmania (Leishmania) infantum in phlebotomine sandflies from a visceral leishmaniasis endemic area in northwestern of São Paulo State, Brazil

This study identified the natural infection rate of Leishmania (Leishmania) infantum in Lutzomyia longipalpis sandflies collected in a neighborhood around a kennel, in Dracena, northwestern of São Paulo state. This region is highly endemic for visceral leishmaniasis in Brazil. Insects were captured during 2-3 nights monthly for 11 months (January-November 2012) using 10 automatic light traps around a kennel in a transition between periurban and urban neighborhood. Capture aimed the determination of the minimal infection rate (MIR) on the area. A total of 1690 Lu. longipalpis were captured during the studied period. Out of them, 292 (17.25%) were females and were grouped in 165 pools containing 1 to five insects for DNA extraction and PCR analysis. Positive results for L. (L) infantum in conventional PCR and real time PCR were shown in 7.28% (12/165) and 4.85% (8/165) of the analysis respectively. These data confirm that Lu. longipalpis captured in the study area were infected by L. (L.) infantum. The MIR of sandflies during the 11 months of captures was 4.10% for female the total of 292 female sandflies collected. A high DNA concentration of L. (L.) infantum was detected on sandflies especially in kennel, chicken coop and neighboring houses, where higher abundance of hosts for blood source were present.

Molecular detection of Trypanosoma cruzi in acai pulp and sugarcane juice

Chagas disease, caused by Trypanosoma cruzi affects about 6-8 million people worldwide. Although transmission by triatomine insects has been controlled, other means of transmission maintain the infection. These forms of transmission are responsible for introducing Chagas disease in other non-endemic countries of the world. Thus, Chagas disease, nowadays is a worldwide health problem. In Brazil, acai pulp and sugarcane juice have been associated with Chagas disease outbreaks. The difficulties in isolation of the parasite from foods are hampering source tracking which could allow the confirmation of an implicated food commodity in these outbreak investigations. To address this scientific gap, we evaluated the performance of real-time PCR (qPCR) for detecting T. cruzi in acai pulp and sugarcane juice. All experiments were performed with acai pulp and sugarcane juice samples contaminated with different concentrations of T. cruzi. In assays with qPCR, the results showed that the ideal procedure for T. cruzi identification in acai pulp and sugarcane juice consisted of: i. centrifugation; ii. DNA extraction with a commercial kit for stool matrix; and iii. qPCR using a specific molecular marker for T. cruzi. The seeding in LIT medium of experimentally contaminated foods was effective in detecting the parasitic load by qPCR. The efficacy of qPCR was also verified testing food samples crushed with infected Triatomines. In conclusion, this methodology can be used to perform rapid diagnosis in outbreaks, facilitating measures in disease control.

Molecular diagnosis of symptomatic toxoplasmosis: a 9-year retrospective and prospective study in a referral laboratory in São Paulo, Brazil

Symptomatic forms of toxoplasmosis are a serious public health problem and occur in around 10–20% of the infected people. Aiming to improve the molecular diagnosis of symptomatic toxoplasmosis in Brazilian patients, this study evaluated the performance of real time PCR testing two primer sets (B1 and REP-529) in detecting Toxoplasma gondii DNA. The methodology was assayed in 807 clinical samples with known clinical diagnosis, ELISA, and conventional PCR results in a 9-year period. All samples were from patients with clinical suspicion of several features of toxoplasmosis. According to the minimum detection limit curve (in C_T), REP-529 had greater sensitivity to detect T. gondii DNA than B1. Both primer sets were retrospectively evaluated using 515 DNA from different clinical samples. The 122 patients without toxoplasmosis provided high specificity (REP-529, 99.2% and B1, 100%). From the 393 samples with positive ELISA, 146 had clinical diagnosis of toxoplasmosis and positive conventional PCR. REP-529 and B1 sensitivities were 95.9% and 83.6%, respectively. Comparison of REP-529 and B1 performances was further analyzed prospectively in 292 samples. Thus, from a total of 807 DNA analyzed, 217 (26.89%) had positive PCR with, at least one primer set and symptomatic toxoplasmosis confirmed by clinical diagnosis. REP-529 was positive in 97.23%, whereas B1 amplified only 78.80%. After comparing several samples in a Brazilian referral laboratory, this study concluded that REP-529 primer set had better performance than B1 one. These observations were based after using cases with defined clinical diagnosis, ELISA, and conventional PCR.