burtonii has a high "IQ" (a measure of adaptive potential) compared to many methanogens.Numerous genes in these two over-represented COG categories appear to have been acquired from ε-and δ-proteobacteria, as do specific genes involved in central metabolism such as a novel B form of aconitase. Transposases also distinguish M. burtonii from other archaea, and their genomic characteristics indicate they play an important role in evolving the M. burtonii genome. Our study reveals a capacity for this model psychrophile to evolve through genome plasticity (including nucleotide skew, horizontal gene transfer and transposase activity) that enables adaptation to the cold, and to the biological and physical changes that have occurred over the last several thousand years as it adapted from a marine, to an Antarctic lake environment.

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Eimeria species, of the Phylum Apicomplexa, cause the disease coccidiosis in poultry, resulting in severe economic losses every year. Transmission of the disease is via the faecal-oral route, and is facilitated by intensive rearing conditions in the poultry industry. Additionally, Eimeria has developed drug resistance against most anticoccidials used today, which, along with the public demand for chemical free meat, has lead to the requirement for an effective vaccine strategy. This review focuses on the history and current status of anticoccidial vaccines, and our work in developing the transmission-blocking vaccine, CoxAbic (Netanya, Israel). The vaccine is composed of affinity-purified antigens from the wall-forming bodies of macrogametocytes of Eimeria maxima, which are proteolytically processed and cross-linked via tyrosine residues to form the environmentally resistant oocyst wall. The vaccine is delivered via maternal immunization, where vaccination of laying hens leads to protection of broiler offspring. It has been extensively tested for efficacy and safety in field trials conducted in five countries and involving over 60 million offspring chickens from immunized hens and is currently the only subunit vaccine against any protozoan parasite to reach the marketplace.

Vaccination with proteins from gametocytes of Eimeria maxima protects chickens, via transfer of maternal antibodies, against infection with several species of Eimeria. Antibodies to E. maxima gametocyte proteins recognise proteins in the wall forming bodies of macrogametocytes and oocyst walls of E. maxima, Eimeria tenella and Eimeria acervulina. Homologous genes for two major gametocyte proteins – GAM56 and GAM82 – were found in E. maxima, E. tenella and E. acervulina. Alignment of the predicted protein sequences of these genes reveals that, as well as sharing regions of tyrosine richness, strong homology exists in their amino-terminal regions, where protective antibodies bind. This study confirms the conservation of the roles of GAM56 and GAM82 in oocyst wall formation and shows that antibodies to gametocyte antigens of E. maxima cross-react with homologous proteins in other species, helping to explain cross-species maternal immunity.

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