Acanthamoebais a microscopic, free-living pathogen which is responsible for causing severeinfections of the eye, skin, and central nervous system. It appears to be oneof the most important protozoa found in natural environment. Acanthamoeba is responsible for causingAcanthameba Keratitis (AK), an infection of the eye which can result in visualimpairment or blindness; Granulomatous Amoebic encephalitis, severe infectionof brain and spinal which mainly occurs in immuno-compromised patients anddisseminated infection, which affects the skin, sinuses and lungs.The majority ofAK strains are associated with genotype T4, but AK strains belonging to othergenotypes have also been reported worldwide (Ledee et al., 2009; Ertabaklar etal., 2007).
Acanthamoeba belonging to genotype T4 has been primarilyassociated with AK; however strains belonging to genotypes T3, T5, T6 and T11have also been found to cause AK. The majority ofAK cases are reported from contact lens wearers belonging to developedcountries. However, in patients from developing countries, the causative factoris majorly corneal trauma or the use of contaminated water (Buehler et al., 2009; Sharma et al., 2000). The chief reason fordeveloping AK are poor hygienic habits including inappropriate storage oflenses, use of contact lenses for long durations, formation of biofilm oncontact lenses and use of tap water as a substitute for lens solution (Siddiquiand Khan, 2012). Detection of AKis quite difficult and hence should be suspected in all lens wearers, peoplehaving corneal trauma with soil, use of contaminated water and in patientsrecovering from ocular surgeries (Lorenzo-Morales et al., 2013).
The diagnosis being problematic, it is oftenmisdiagnosed as fungal, bacterial or viral keratitis.A deeperunderstanding of the proteins expressed by various Acanthamoeba spp. might helpin the diagnosis and treatment of this vulnerable disease. In reference to thisour study aims to compare the protein profiles of various Acanthamoeba specieswhich will help in gaining a better understanding about the diseasepathogenesis and will eventually contribute towards the culmination ofeffective diagnosis. Reviewof Literature Acanthamoeba isone of the primary causes of keratitis which is a painful sight-threateningcorneal infection.
It is an opportunistic amoeba which is found globally. Itspresence has been reported from all kinds of natural environments including seawater, pond water, beaches, springs and even air. Reportedly, it has beenisolated from packaged mineral water, vegetables, air conditioners, sewage. It was alsofound from hospitals, dialysis units, human nasal cavities, throat, pharyngealswabs, lung tissues and human feces (Siddiqui and Khan 2012). The reason forthe wide distribution of Acanthamoeba is due to its ability to withstand allkinds of harsh weather conditions. The universal presence of Acanthamoeba isthe reason for humans to get easily infected with it and fall prey to AK. The life cycleof Acanthamoeba consists of two stages: a vegetative growing trophozoite stageand an inactive dormant cyst stage. The trophozoite is about 14-40 µm indiameter whereas the double walled cyst is about 12-16 µm in diameter.
In most of thedeveloped countries, generally the contact lens wearers report with cases of AKdue to the negligence posed during handling and storage of contacts. Incontrast the cases reported from India and other developing countries come fromnon contact lens wearers and those who are working in agricultural fields,one’s that come in contact with contaminated water and soil. A study in southIndia reported an epidemic of AK in rural, non contact lens wearers in 1993 and2003 (Lalitha et a.,l 2012). In spite of thedifference in the source of AK, the problems and disease severity posed byAcanthamoeba are almost similar in developing as well as developed nations.
Patientssuffering from AK might suffer ocular pain with photophobia, ring like stromalinfiltrates and lid oedema (Lorenzo-Morales et a.,l 2015).On the basis of18S rDNA sequencing Acanthamoeba has been classified into 20 differentgenotypes (T1-T18) (Huang et a.,l2016). Till date the majority of studies have considered T4 as the causativegenotype behind AK, however Siddiqui and Khan in 2012 have reported T2, T3, T4,T5, T6, T10, T11, T13 and T15 to be related with AK in humans. But there islimiting knowledge on different Acanthamoeba genotypes based on theirrespective protein profiles (Pumidonming et a.,l 2014).
These days a largenumber of proteomic studies are being used to explore secreted proteins andstudy disease pathogenesis. For example, Lourenssen et al., 2010 have reported about a large number of proteins whichcause amoebic colitis by disrupting the mucus layer. Also Lorenzo-Morales et al., 2002 and Mattana et al., 2002 have reported thatAcanthamoeba produces serine, cystein and metalloproteases and extracellularprotease activities are elevated in pathogenic Acanthamoeba strains. Thisclearly shows the importance of proteomic based study and its role in studyingdisease pathogenesis. Aimof the study To establish a proteomic dataset ofextracellular secretory proteins of 11 Acanthamoeba isolates.
Perform a comparative proteomic analysisof proteins from all the Acanthamoebaisolates to be considered MethodologyThe study willtake into consideration 11 Acanthamoeba isolates of five different genotypesand a comparative proteomic analysis will be carried out which will help indevising a much more efficient diagnostic method. An overview ofthe methodology:Acanthamoeba species will be axenicallycultured in a suitable medium.Extracellular secretory proteins will beisolated and will be subjected to 2D Gel electrophoresis which will help in theanalysis of complex protein mixture.Separated proteins will be identifiedusing MALD TOF/TOF MS which will help in identifying and genotyping variousAcanthamoeba isolates. References Buehler PO, Schein OD, StamlerJF, Verdier DD, Katz J. The increased risk of ulcerative keratitis amongdisposable soft contact lens users. Archives of Ophthalmology. 1992 Nov1;110(11):1555-8.
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