Investigating Unique DNA Sequences of L. albertoi from Ocular Disease for Diagnostic Purposes

Abstract

Purpose: Some species in Oomycetes class infect the mammalian species causing life threatening infection. The first described Oomycete infecting mammals was Pythium insidiosum. More recently several species of Lagenidium were reported to be causing infections, identical to one observed in cases of pythiosis in cats, dogs, horses and humans. We propose to analyze DNA epitops (CDC-42 DNA coding gene, HSP90, and 18S SSUrDNA) in the particular strain Lagenidium albertoi using all available oomycete DNA sequences data available in NCBI, to investigate the presence of the pathogen unique regions that could be used to differentiate this particular strain from the other Oomycetes and fungi with similar phenotypic characteristics.

Methods: We have selected the strain of Lagenidium albertoi* isolated from a Thai human with keratitis, to systematically characterize this strains looking for unique regions and use them to differentiate it from the other mammalian pathogenic saprophytic oomyectes.

Results: Our data showed several genes sequences present within the CDC42, COXII, and HSP90 coding DNA epitops and the Internal Transcriber Spacers (ITS) DNA sequence that can be used for the PCR specific identification of Lagenidiumalbertoi causing ocular infections in humans. Among these epitops,COXII and ITS amplicons showed highly variable regions that can be used for to build specific primers. Those DNA regions are currently tested with several genomic DNA from oomycetes and filamentous fungi to validate their uniqueness and their specificity for L. albertoi.

Conclusions: It is important to define the appropriate method to diagnose Lagenidium spp. The most accurate way to do it is using molecular tools by building new primers to amplify gene epitops in L. albertoi. The differentiation between P. insidiosum and Lagenidium spp. is required for appropriate management, since the latter pathogen is more aggressive, with a poor prognosis, and does not respond well to the treatment established for Pythium.

Keywords: 594 microbial pathogenesis: experimental studies • 468 clinical research methodology • 479 cornea: clinical science