Neospora caninum is a recently recognized protozoan parasite of animals. Until 1988, it was misdiagnosed as Toxoplasma gondii. Neospora caninum or Neospora-like parasites cause paralysis and death in dogs and neonatal mortality and abortion in cattle, sheep, goats and horses. Its life cycle is not known. Tachyzoites and tissue cysts are the only asexual stages known and the carnivorous definitive host is not known. Transplacental transmission is the only known natural route of infection.
Mononuclear cells, CD2+ T cells and T subsets (CD4+, CD8+) from HLA-typed malaria-naive donors were stimulated with isolated surface antigens (Ags) from Plasmodium falciparum merozoites (MSP183, MSP136, MSP2). Cell responses in lymphocyte proliferation assays were MHC-class II and mainly DR restricted. Donors could be grouped into high, non or low responders according to the proliferative response. The high responders possessed the combination DR7/DRw53 as a common HLA-restriction
element. Non and low responders did not have this Ag combination, but some were characterized by DQw1.
Individual donors did not show any Ag dependent response. CD45RA+ (naive, non-stimulated) enriched T cells from high-responders were strongly stimulated by the merozoite Ags, whereas stimulation of CD45R0+ (memory) enriched T cells was much lower.
The surface of the protozoan Gastrostyla steinii undergoes profound morphological changes during the encystment and excystment processes. Resorption of the various ciliary structures occurs progressively during differentiation of the free living cell into the resting cyst. In ciliar disassembly, layers of the cyst wall are deposited on the surface of the encysting organism. At excystation, the hatching trophozoite emerges from the protective wall through a cleft after the formation of the ciliary organelles.
Large numbers of cyclophosphamide- or carrageenan-pretreated immunosuppressed adult ddY mice died within 10 days after inoculation with several species of opportunistic bacteria, including P. aeruginosa, K. pneumoniae, E. coli, S. aureus and methicillin resistant S. aureus. When immunosuppressed mice were administered bacteria in combination with two 100 μg/mouse intramuscular doses of a newly synthesized peptide, Obiopeptide-1 (OP-1), survival rates increased significantly. At 24 and 48 hours after intraperitoneal inoculation with P. aeruginosa, counts of viable organisms from the livers, spleens, lungs, hearts, and kidneys of mice that were administered cyclophosphamide in combination with OP-1 were significantly lower than counts from mice that were administered cyclophosphamide alone. Bacteriocidal activity of peritoneal cells, neutrophils and monocyte-macrophages was higher in OP-1 pretreated mice than in non-OP-1 treated mice. This newly synthesized peptide, OP-1, is a potential immunomodulator which increases host resistance against bacterial infection. The peptide may also function as a nonspecific blood stimulating factor.