Alternate Hosts for Cryptococcus neoformans

There are a few in vivo models for the study of Cn infection and each has its own advantages and disadvantages. Acanthameoba castellanii is a good nonmammalian host for Cn infection (Steenbergen et al., 2001) as many of the hallmarks of Cn infection in macrophages are also seen in amoeba and amoeba are viable at 37°C. Dictyostelium discoideum (Steenbergen et al., 2003) is another important nonmam-malian host because of the many similarities seen between infection of Cn and macrophages. There are a few major advantages of this system in that Dictyostelium is a genetically malleable host and there are numerous mutant lines available, unlike A. castellanii. However, slime mold amoeboid cells are smaller than amoebae and are less efficient at phagocytosis. Thus, both systems have advantages and disadvantages for studying the genetics of the interaction between Cn and its potential environmental host.

Another genetically malleable non-mammalian host is the worm Caenorhabditis elegans (Mylonakis et al., 2002, 2003). This host model is probably the most extensively used to study Cn infection thus far because there are many genetic tools available, such as a variety of mutant lines, RNA interference (RNAi) libraries and microarrays. In addition, its genome is sequenced and annotated. Research using C. elegans has already identified two different genes involved in virulence of Cn. Kin1 is a protein kinase homologue that binds macrophages and is associated with virulence in mice (Mylonakis et al., 2004). Rom2 is a guanyl-nucleotide exchange factor homologue that has a significant role in growth at 37°C, mating and the maintenance of the stability of the cell wall under osmotic pressures. It is also associated with virulence in mice (Tang et al., 2005).

Another model host for Cn infections is Drosophila melanogaster (Apidianakis et al., 2004). This host is useful for the study of innate immune responses to Cn infections as there is a high degree of conservation between mammals and insects. In addition, Drosophila is also genetically malleable with a large number of mutant lines available. It has a sequenced and annotated genome and RNAi libraries and microarrays are available. A recently studied model for Cn infection is the greater wax moth caterpillar Galleria mellonella (Mylonakis et al., 2005). This is a particularly useful host model because some of the disadvantages with the other models are not a problem. For example, with G. mellonella it is possible to administer exact fungal inocula by injection, unlike C. elegans and D. melanogaster, which have to ingest Cn to be infected. In addition, this host can be studied at higher temperatures (37°C) and can be used to study the effects of antifungal compounds. One major disadvantage, however, is the lack of genetic tools available for G. mellonella.

Cure Your Yeast Infection For Good

Cure Your Yeast Infection For Good

The term vaginitis is one that is applied to any inflammation or infection of the vagina, and there are many different conditions that are categorized together under this ‘broad’ heading, including bacterial vaginosis, trichomoniasis and non-infectious vaginitis.

Get My Free Ebook

Post a comment