Acanthamoebidae

Acanthamoebidae is a family of single celled eukaryotes within the group Amoebozoa.

It gets its name from Acanthamoeba, its best known member. However, it also includes other species, such as Comandonia operculata and Protacanthamoeba bohemica.^[1] Many kinds of Acanthamoebidae are highly prevalent in the soil and water of a variety of environments.^[2][3] They are similar to Hartmannella, but have differently structured pseudopodia, in regard to the actin microfilaments that comprise them. Its most prominent member, Acanthamoeba, can be potentially pathogenic to humans and animals.^[3]

It has been described as having a common origin with Entamoebidae and Dictyosteliida.^[4]

Structure

Members of Acanthamoebidae have a specific form of pseudopodia, dubbed acanthopodia.^[5] These acanthopodia are continuously formed and reabsorbed, protrude from every area of the body’s surface, and are usually, though not without exception, short and fine. An exception would be A. astronyxis and A. comandoni, in which the acanthopodia may be quite long.^[5] Sawyer and Griffin point out “Bundles of actin microfilaments extend as rigid cores into acanthopodia”.^[5] They are constantly formed and reabsorbed to induce locomotion, during which time the cell is typically triangular or cone shaped.^[5] The advancing acanthopodia are “wide and tongue-shaped, with irregular margins and filopodia.”^[5] Sawyer and Griffin also note that the many acanthopodia contain axial bundles of the actin microfilaments, resulting in the irregular shape of the pseudopodia.^[5] In regards to the typical physical size of the Acanthamoebidae family, they rarely grow larger than 65 µm or are smaller than 30 µm.^[5]

Classification

The family of Acanthamoebidae is within the amoebozoa group, which in turn is within the domain of eukaryota. Within the family Acanthamoebidae are the genera Acanthamoeba, Comandonia, and Protacanthamoeba, among others.

Prevalence

Members of Acanthamoebidae are highly prevalent in a variety of environments. In Osaka Prefecture, Japan, members of Acanthamoebidae (as well as Naegleria) were found in 68.7% of tap water samples taken, despite purification.^[2] Acanthamoebidae was also found in the St. Martin River near Ocean City, Maryland, and is very common in the surface waters of many oceans.^[3]

Pathology

The most prominent member of Acanthamoebidae, Acanthamoeba, can be potentially pathogenic to humans and animals.^[3] Typically, a person or animal with a normally functioning immune system can avoid infection; Edagawa et al. states, Acanthamoeba "are known to be the opportunistic pathogens in granulomatous amoebic encephalitis (GAE), a chronic disease of immuno-compromised hosts such as AIDS patients and transplants recipients.”^[2] GAE is the result of microscopic cysts that form in the central nervous system. Acanthamoeba can also be the source of infections in the lungs, sinuses, skin, and eyes.^[2]

References