Developmentally regulated transcripts and evidence of differential mRNA processing in Giardia lamblia.

Although encystation and excystation are crucial to transmission of Giardia lamblia, little is known about the regulation of these very distinct differentiation processes. Fingerprinting of giardial mRNA populations throughout the time course of differentiation demonstrated complex patterns in mRNA differential display. Certain transcripts appeared or increased, while others decreased or disappeared at specific times, in response to physiologic stimuli that mimic key stages in parasite descent through the host gastrointestinal tract.

Bovine vaginal antibody responses to immunoaffinity-purified surface antigen of Tritrichomonas foetus.

Bovine trichomoniasis is a prevalent sexually transmitted disease of cattle caused by the protozoan Tritrichomonas foetus. Currently, diagnosis is most often made by culture. In order to provide a faster immunodiagnostic approach, a specific enzyme-linked immunosorbent assay (ELISA) was investigated.

Giardia lamblia: post-translational processing and status of exposed cysteine residues in TSA 417, a variable surface antigen.

Giardia lamblia develops and thrives within the harsh and variable environment of the human small intestine. To survive this environment, Giardia has evolved a unique family of antigenically variable, extremely cysteine-rich surface proteins. We have characterized the expression of one of these antigens, TSA 417, at the gene and protein levels.

Molecular analysis of a gene encoding a serum-resistance-associated 76 kDa surface antigen of Haemophilus somnus.

Haemophilus somnus is a Gram-negative bacterial bovine pathogen which can cause disease or be carried asymptomatically. We previously showed that four serum-sensitive isolates from asymptomatic carriers lacked a 13.4 kb sequence of chromosomal DNA that was present in two virulent serum-resistant strains.

Site-directed mutations in the relaxase operon of RP4.

Mutations were constructed by site-directed mutagenesis in the relaxase operon of the broad-host-range plasmid RP4. The mutations were constructed in smaller plasmids, recombined into the 60-kb RP4 plasmid, and tested for their ability to transfer. The relaxase operon contains the transfer genes traJ, traH, and traI, which are involved in nicking at the transfer origin to generate the single strand destined to be transferred to the recipient cell.

Human secretory and serum antibodies recognize environmentally induced antigens of Giardia lamblia.

The variability in duration and severity of infection with Giardia lamblia is likely to be due to trophozoite interactions with immune and nonimmune components of the small intestinal milieu. Despite its potential importance, nothing is known of the isotype or the specificity of the secretory antibody response to G. lamblia.