The clinical features of congenital ocular toxoplasmosis

Congenital infection is more common later in gestation, but disease manifestations are worse if acquired earlier in gestation (Dunn et al., 1999). Classically, congenital disease is associated with bilateral macular scarring, but acquired infection can also result in macular disease and, rarely, bilateral scarring as well (Glasner et al., 1992). Other manifestations include optic neuritis, iritis, neuroretinitis, retinal vasculitis, acute retinal necrosis, recurrent iridocyclitis, and...

Role of GPIs in cell signaling and host immune response

Except for their role in membrane insertion of surface proteins in T. gondii, the biological junctions of GPIs are presently unknown. In other eukaryotic systems, GPIs can display functions involved in signal transduction. One possible function of the GPI anchor might be to allow a closer association of the proteins with themselves and other surface proteins in the membrane (Tomavo, 1996). Consistent with this idea, genetically engineered transmembrane-anchored SAG1 does not show the usual...

Models based on systemic infection

As can be seen in some 20 publications, meanwhile, the most frequently used animal for systemic infection models is the mouse. Basically, two different methods have been employed to establish the disease 1. Infection of pregnant mice to induce the development of ocular lesions in the pups (Hay et al., 1981, 1984 Hutchison et al., 1982 Lee et al., 1983 Dutton et al., 1986) 2. Systemic infection of mice which then predominantly develop ocular manifestations (Gazzinelli et al., 1994 Olle et al.,...

The mitochondrial genome

Despite considerable variation in size and gene content among species, all mitochondrial genomes known to date encode apocytochrome b (cob) and cytochrome c oxidase I (coxl). Cytochrome c oxidase III (cox3) is nearly invariant, missing from the mitochondrial genome only in some green algae. Mitochondrial genomes also invariably encode eubacterial-like large and small subunit rRNAs (reviewed in Gillham, 1994 Lang et al., 1999 Gray et al., 2004). The T. gondii mitochondr-ial genome has proven...

Densegranule protein function more hypotheses than functions

As mentioned above, to date the function of most dense-granule proteins remains unknown. At the tachyzoite stage, their burst of secretion into the PV following host-cell invasion and their selective targeting within the PV compartment suggest that they might contribute significantly to the structural organization of this new compartment and or have important functions in PV metabolism (Dubremetz et al., 1993 Cesbron-Delauw et al., 1994 Carruthers and Sibley, 1997). BLAST searches performed on...

Toxoplasmosis In Humans

Three pathologists - Wolf, Cowen, and Paige, from New York, USA - first conclusively identified T. gondii in an infant girl who was delivered full term by Caesarean section on 23 May 1938 at Babies' Hospital, New York (Wolf et al., 1939a, 1939b). The girl developed convulsive seizures at 3 days of age, and lesions were noted in the maculae of both eyes through an ophthalmoscope. She died when a month old, and an autopsy was performed. At post mortem, brain, spinal cord, and right eye were...

Toxoplasmosis In Other Animals

Mello (1910), in Turin, Italy, first reported fatal toxoplasmosis in a domestic animal (a 4-month-old dog) that died of acute visceral toxoplasmosis. Over the next 30 years, canine toxoplasmosis was reported in Cuba, France, Germany, India, Iraq, Tunisia, the USSR, and the USA (Dubey and Beattie, 1988). Campbell et al. (1955) found that most cases of clinical toxoplasmosis were in dogs infected with canine distemper virus (CDV). Even vaccination with live attenuated CDV vaccine can trigger...

Energy metabolism

The mitochondrion is commonly described in introductory biology classes as the powerhouse of the cell. It is the site of the tricarboxylic acid cycle and the electron transport chain, which act in concert to efficiently convert the products of glucose catabolism to ATP. The other functions of the organelle often get little mention. However, while mitochondrial respiration is key for aerobi-cally respiring cells, many parasite cells are found in environments with low oxygen tension and rely at...

Why does T gondii exhibit this patchwork of MICs

The vast MIC repertoire of T. gondii may be correlated with the broad host-cell specificity in vitro and the spreading of infection in all organs in toxoplas-mosis, contrasting with the high cell and organ specificity found in Plasmodium. Apicomplexa show variable cell specificity, particularly at different stages of infection specificity may be related to the MIC repertoire, quite different from one genus to the other, and dependent upon the stage in the life cycle. MIC gene deletion in T....

T gondii displays a uniquely simple pathway for amylopectin synthesis

Using bioinformatic searches, several gene candidates encoding enzymes that are probably involved in amylopectin biosynthesis were identified Coppin et al., 2005 . These putative enzymes can be grouped in two classes 1. Enzymes that are involved in amylopectin synthesis, such as amylopectin synthase, branching enzymes, UDP-glucose pyrophosphorylase, isoamylase, indirect debranching enzyme, a-1, 4-glucanotransferase, and glycogenin 2. Enzymes for amylopectin degradation, like a-amylase, dikinase...