The asexual cycle of apicomplexan parasites: new findings that raise new questions

Markus Meissner is a Wellcome Trust Senior Fellow at the Wellcome Trust Centre for Molecular Parasitology at the University of Glasgow. His research focuses on the mechanisms involved in the invasion of the host cell by apicomplexan parasites. Using Toxoplasma gondii as a model system his group investigates the biogenesis, maintenance and regulation of these organelles. The research goals include identification and analysis of essential genes linked to invasion and modulation of the host cell using forward genetic screens. The group is also investigating host cell factors required for the invasion and growth of the parasite to understand the interdependence between the parasite and its host. The phylum apicomplexa consists of more than 5000 species, including important human and veterinary pathogens that have a huge, global effect on human and animal health. While Plasmodium spp. (the causative agent of malaria) is the most notorious member of this phylum causing approximately 660 000 deaths a year, other apicomplexans are among the most relevant foodborne pathogens of global socio-economic relevance. For example Eimeria spp. are the most important protozoan pathogens of poultry. Other important apicomplexan pathogens include Cryptosporidium spp., Neospora caninum, Theileria spp. or Toxoplasma gondii. While most apicomplexans show a relatively small host range, Toxoplasma gondii, infects all nucleated cells from warm blooded animals and has a huge impact on both human and animal health. This parasite is a major cause of abortion in livestock, with significant economic losses to sheep and goat breeders. In addition, it is one of the leading causes of death attributed to foodborne illness. Especially the primary infection during pregnancy, which can cause serious damage of the unborn child and the reactivation of dormant tissue cysts in immunocompromised patients are the most common complications caused by a Toxoplasma infection.