Diagnostic and prognostic value of cell free circulating Schistosoma mansoni DNA: an experimental study

Abstract

Searching for a more sensitive and accurate marker for schistosomiasis diagnosis and treatment follow up is a potential necessity. Hereby, we evaluated usefulness of circulating free DNA as a marker for schistosomiasis diagnosis, assessing drug efficacy and monitoring the control interventions impact using SYBR green real-time PCR. A batch of mice were infected by 90 ± 10 Schistosoma mansoni cercariae. Starting from the 2nd day post infection (p.i.), groups of 2 or 3 mice were sacrificed every 3 days until 30 days p.i. The remaining animals were treated by a single dose of 400 mg/kg mefloquine and sacrificed in group at 5, 10, 21 days post treatment (35, 40, 51 days p.i.). Using SYBR green real time qPCR, pooled sera DNA were extracted and amplified. The results showed that, circulating free S. mansoni DNA was detected from the 2nd day post infection (p.i.) onwards with gradual decrease in the cycle threshold value C t which indicates the gradual elevation of the DNA level (Log quantity was 2.6-3.1 IU/ml), As the infection progressed, DNA quantity was increased(Log quantity was 6.29 IU/ml). Initial increase of circulating free DNA was observed 10 days post treatment (40 days p.i.) (Log quantity was 7.38 IU/ ml). That was followed by a progressive decrease in DNA level by the end of 21st day, post treatment (51 p.i.) (Log quantity 4.35 IU/ml). In conclusion, circulating free S. mansoni DNA is a reliable marker in the diagnosis of schistosomiasis and for assessing drug efficacy and monitoring the impact of control interventions.

Evaluation of serum-based real-time PCR to detect Schistosoma mansoni infection before and after treatment

“…This was followed by an increase in the Ct value at the second follow-up examination (20 weeks after treatment median Ct was 34.9), which, was higher than at baseline (median Ct 30.3). Similar results have been reported in other studies [19,42]. Since people with chronic infections have a large number of eggs in their tissues and DNA is probably released at very slow kinetics, free-circulating DNA may be detected several months after therapy [30,43].…”

Development of a laboratorial platform for diagnosis of schistosomiasis mansoni by PCR-ELISA

“…Schistosoma spp. has at least 600,000 copies of the 121 pb repetitive sequence in each cell, which constitutes 12% of the S. mansoni genome [ 13 ]. Therefore, in this work, all procedures were done by a trained researcher and physical barriers were utilized in all sample handling steps of the laboratorial and commercial PCR-ELISA platforms to minimize the risk of contamination.…”

Avaliação dos diversos métodos diagnósticos para esquistossomose em regiões endêmicas desassistidas brasileiras: um olhar para Alagoas

“…Avaliação dos métodos de diagnóstico.O teste diagnóstico padrão para a esquistossomose, a técnica Kato-Katz, é voltado para análise da quantidade de ovos nas fezes, possuindo baixo custo para realização e grande disponibilidade por requerer basicamente um microscópio óptico para sua realização, como observado na Tabela I16 .Ao longo dos anos, o método padrão foi adaptado para o aumento da sua eficiência ao incluir no seu protocolo a coleta de três amostras fecais ao invés de uma, como no método clássico de Kato Katz, ainda de acordo com a Tabela I17 . Um outro exame seria a técnica de reação em cadeia de polimerase (PCR), visto na Tabela II, que é comprovadamente mais sensível que o Kato-Katz 18 e tem a possibilidade de identificar indivíduos que já possuíram essa infecção19 , sendo possível identificar casos de fibrose relacionados à doença já tratada.Entretanto, tem disponibilidade limitada e alto custo quando comparado a outras técnicas. de ovos nas fezes do indivíduo, além de ter baixo custo21 .…”