Characterization of ROP18 alleles in human toxoplasmosis
Víctor Sánchez1, Alejandra de-la-Torre1, Jorge Enrique Gómez-Marín1
1Grupo de Estudio en Parasitología Molecular (GEPAMOL), Centro de Investigaciones Biomédicas, Facultad de Ciencias de la Salud, Universidad del Quindio, Armenia (Q), Colombia.
Abstract:
The role of the virulent gene ROP18 polymorphisms is not known in human toxoplasmosis. A total of 320 clinical samples were analyzed. In samples positive for ROP18 gene, we determined by an allele specific PCR, if patients got the upstream insertion positive ROP18 sequence Toxoplasma strain (mouse avirulent strain) or the upstream insertion negative ROP18 sequence Toxoplasma strain (mouse virulent strain). We designed an ELISA assay for antibodies against ROP18 derived peptides from the three major clonal lineages of Toxoplasma. 20 clinical samples were of quality for ROP18 allele analysis. In patients with ocular toxoplasmosis, a higher inflammatory reaction on eye was associated to a PCR negative result for the upstream region of ROP18. 23.3%, 33% and 16.6% of serums from individuals with ocular toxoplasmosis were positive for type I, type II and type III ROP18 derived peptides, respectively but this assay was affected by cross reaction. The absence of Toxoplasma ROP18 promoter insertion sequence in ocular toxoplasmosis was correlated with severe ocular inflammatory response. Determination of antibodies against ROP18 protein was not useful for serotyping in human toxoplasmosis.
Insights
The virulent gene ROP18 polymorphisms are linked to human toxoplasmosis severity. Absence of the ROP18 promoter insertion sequence correlated with severe ocular inflammation in toxoplasmosis patients.
Area of Science:
- Parasitology
- Immunology
- Genetics
Background:
- Toxoplasmosis is a significant human parasitic infection.
- The role of the ROP18 gene, particularly its polymorphisms, in human toxoplasmosis pathogenesis remains unclear.
- ROP18 is a key virulence factor in Toxoplasma gondii.
Purpose of the Study:
- To investigate the association between ROP18 gene polymorphisms and the clinical presentation of human toxoplasmosis.
- To determine if specific ROP18 alleles correlate with disease severity, especially in ocular toxoplasmosis.
- To evaluate the utility of ROP18-based serotyping in human infections.
Main Methods:
- Analysis of 320 clinical samples for the presence of the ROP18 gene.
- Allele-specific PCR was used to differentiate between ROP18 strains with (avirulent) or without (virulent) the upstream insertion sequence.
- ELISA was developed to detect antibodies against ROP18 peptides from major Toxoplasma clonal lineages, though cross-reactivity was noted.
Main Results:
- In patients with ocular toxoplasmosis, a negative PCR result for the ROP18 upstream region was associated with a higher inflammatory response in the eye.
- The absence of the Toxoplasma ROP18 promoter insertion sequence was correlated with severe ocular inflammatory responses.
- Antibody detection against ROP18 protein showed cross-reactivity and was not useful for serotyping in human toxoplasmosis.
Conclusions:
- ROP18 polymorphisms, specifically the presence or absence of the promoter insertion sequence, play a role in the severity of human ocular toxoplasmosis.
- The investigated ROP18 allele-specific PCR is a potential tool for assessing disease severity.
- Antibody-based detection of ROP18 is not a reliable method for serotyping in human toxoplasmosis.
