Classification of Acanthamoeba

Classification of Acanthamoeba
Some members of the genus Acanthamoeba have been found to be pathogenic (see Pathogenicity of Acanthamoeba) to man and so it is important to establish which strain from which environment present the greatest danger. Classification of the genus is therefore crucial to this effort. Acanthamoebae have been classified into three groups by morphologically of the cysts (Pussard & Pons, 1977), Table 1.

Group 1
Group 2
Group 3
Table 1.
This classification scheme enjoyed popular support but it has been pointed out that cyst morphology can be affected by the conditions under which the cysts were formed (Sawyer, 1971). Other methods such as isoenzyme analysis and mitochondrial DNA analysis have also been deployed but no entirely satisfactory resolution has been reached by these methods to firmly establish intra-genus relationships. However, these methods did show for example that species described as A. polyphaga most probably, did not form a distinct species (Kong et al, 1995), that A. After a huge amount of work by the laboratory of Thomas Byers (Stothard et al, 1998) involving the determination of 35 new sequences of strains I feel (communications very welcome!) that SSUrDNA is the way to proceed but that in addition what is needed is independent confirmation by sequence analysis of other genes or gene products. I suggest that a possible candidate is the gene for actophorin. I would admit immediately that I have a vested interest in this choice since this is a gene very close to my other professional interest (Quirk et al, 1993).
Relations with other organisms
References:- Kong, H.-H., Park, J.-H., & Chung, D.I. (1995). "Interstrain polymorphisms of isoenzyme profiles and mitochondrial DNA fingerprints among seven strains assigned to Acanthamoeba polyphaga." Korean J. Parasitol. 33(4), 331-340. Pussard, M. & Pons, R. (1977). "Morphology de la paroi kystique et taxonomie du genre Acanthamoeba (Protozoa, Amoebida). Protistologica, 8, 557-598. Quirk, S., Maciver, S.K. , Ampe, C., Doberstein, S.K., Kaiser, D.A., VanDamme, J., Vandekerckhove, J.S., and Pollard, T.D.(1993). "Primary structure of and studies on Acanthamoeba actophorin." Biochemistry 32, 8525-8533. Sawyer, T.K. (1971). "Acanthamoeba griffini, a new species of marine amoeba." J.Protozool. 18, 650-654. Stothard, D.R., Schroeder-Diedrich, J.M., Awwad, M.H., Gast, R.J., Ledee, D.R., Rodriguez-Zaragoza, S., Dean, C.L., Fuerst, P.A., & Byers, T.J. (1998). "The evolutionary history of the genus Acanthamoeba and the identification of eight new 18S rRNA gene sequence types." J.Euk.Microbiol. 45(1), 45-54. Walochnik, J., Haller-Schober, E. M., Kolli, H., Picher, O., Obwaller, A. & Aspock, H. (2000) Discrimination between clinically relevant and non-relevant Acanthamoeba strains isolated from contact lens-wearing keratitis patients in Austria., J.Clin. Microbiol. 38, 3932-3936. Walochnik, J., Hassl, A., Simon, K., Benyr, G. & Aspöck, H. (1999) Isolation and identification by partial sequencing of the 18S ribosomal gene of free-living amoebae from necrotic tissue of Basiliscus plumifrons (Sauria: Iguanidae)., Parisitol.Res. 85, 601-603. Walochnik, J., Obwaller, A. & Aspock, H. (2000) Correlations between morphological, molecular biological, and physiological characteristics in clinical and non-clinical isolates of Acanthamoeba., Appl.Environmental Microbiol. 66, 4408-4413. Walochnik, J., Obwaller, A. & Aspock, H. (2001) Immunological inter-strain crossreactivity correlated to 18S rDNA sequence types in Acanthamoeba spp., Int.J.Parasit. 31, 163-167.