Pure cultures of a trypanosomatid isolated from tomato fruits infected laboratory‐raised tomatoes and nymphs of the hemipieran coreid Phthia picta. The flagellate could be transmitted back and forth from tomatoes to insects. Light and electron microscopy studies were done on culture, tomato and insect forms. Examination of enzymes of the ornithine‐arginine metabolism revealed absence of arginase and presence of arginine deiminase and citrulline hydrolase. Monoclonal antibodies specific for Phytomonas spp. reacted positively with tomato and insect forms. Endonuclease digestion of the k‐DNA of various Phytomonas spp. revealed a unique, distinctive pattern for the tomato flagellate. This flagellate thus seems to constitute a separate species of Phytomonas which we now call Phytomonas serpens (Gibbs).

The immune cross-reactivity between Trypanosoma cruzi, the protozoan that causes Chagas' disease, and Phytomonas serpens, a trypanosomatid that infects tomatoes, was studied. Sera from patients with Chagas' disease presented a strong reactivity with P. serpens antigens by conventional serological assays such as indirect immunofluorescence (IIF) and direct agglutination test (DAT), confirmed after cross-absorption experiments. The results show that this protozoan is highly immunogenic and that rabbit and mouse hyperimmune serum raised against T. cruzi or P. serpens was able to recognize both T. cruzi and P. serpens antigens in immunofluorescence and agglutination assays. The antigenic cross-reactivity between T. cruzi and P. serpens was also demonstrated in vivo. BALB/c mice immunized by the intraperitoneal or oral route with P. serpens and later challenged with a lethal inoculum of T. cruzi blood forms showed a significant decrease in parasitemia and increase in survival compared to controls. A practical implication of these findings is that the ingestion by humans or animals of living plant trypanosomatids present in naturally infected edible fruits could potentially prime the immune response to T. cruzi antigens and interfere with the development of T. cruzi infection.

ABSTRACT. Trypanosomatids isolated from corn seeds and from digestive tract and salivary glands of Leptoglossus zonatus (Hemiptera, Coreidae) were obtained in pure cultures. In experimental transmission, the flagellates present in naturally infected insects were able to infect laboratory‐raised corn. A simplified liquid culture medium was established that increased parasite yield three‐ to five‐fold. Cultured and cloned parasites, and forms found in insects and corn as well, were studied by light and electron microscopy. A remarkable finding was the observation that the cultured strain 163M bears a surface coat similar to that observed in naturally occurring African trypanosomes. but not observed in trypanosomes in vitro. Based on the biochemical characteristics of the arknine‐ornithine cycle and on the presence of this cell coat, we propose that the strain 163M is a new species and name it Herpetomonas macgheei n. sp.

Trypanosomatids recently isolated from the plants Euphorbia pinea, E. characias, E. hyssopifolia, Manihoi esculenta (cassava) and Lycopersicon sp. (tomato) plus the McGhee‐Postell isolate of Phytomonas davidi have been examined for the presence of enzymes of ornithine‐arginine metabolism. Arginase (EC 3.5.3.1) was not detected in the flagellates examined whereas arginine deiminase (EC 3.5.3.6) and citrullinehydrolase (EC 3.5.1.20) were present in all organisms. Phytomonas davidi and the isolate from E. hyssopifolia, besides these enzymes, also had ornithine carbamoyltransferase (EC 2.1.3.3). The enzymic constitution of these flagellates is compared from a taxonomic standpoint to that of previously studied trypanosomatids.

Electron microscopy of salivary glands of the phytophagous hemipteran Phthia picta infected with Phytomonas serpens revealed the presence of flagellates in the gland periphery beneath the gland envelope, in the gland central lumen, between gland cells in the intercellular space and inside the gland cells. In the latter case, flagellates were found in the cytoplasm whether or not it was surrounded by a vacuolar membrane. Flagellates were always of the promastigote type, sometimes displaying a large twisted body. Morphological peculiarities of flagellates in different gland locations are recorded.

No abstract

Abstract. A Western blot method that uses antigens from culture promastigote forms of Leishmania (Viannia) braziliensis, L. (Leishmania) amazonensis, L. (Leishmania) tropica, and a trypanosomatid (strain 268T) isolated from naturally infected tomatoes was evaluated for laboratory diagnosis of American tegumentary leishmaniasis (ATL). Serum samples were obtained from 108 patients with ATL (group I), 23 chagasic patients (group II), 32 patients with other diseases (group III), and 78 healthy individuals (group IV). The overall analysis showed a sensitivity of 76.90%, 90.40%, 78.50%, and 87.90%, a specificity of 100%, 93.80%, 87.80%, and 77.10%, a positive predictive value of 100%, 94.00%, 89.50%, and 72.50%, a negative predictive value of 75.70%, 90.00%, 75.40%, and 90.20%, and a concordance coefficient kappa of 0.7358, 0.8400, 0.6491, and 0.6287 for L.(L.) tropica, and strain 268T antigens, respectively. The antigenic profile recognized by serum samples from patients with ATL and with Chagas' disease permits serologic distinction between these infections.

The most frequent form of acquisition of Chagas' disease in endemic areas was the transmission through the feces of contaminated triatominae. However, special attention should be paid in urban areas to transmission by blood transfusion, justifying the compulsory screening of blood donors. Early investigations at blood banks in the town of Londrina, Brazil, demonstrated that the seroprevalence of anti-Trypanosoma cruzi antibodies among blood donors was approximately 7.0% in the fifties9,34. Further studies demonstrated pratically the same seroprevalence until the eighties4,32,41. In an attempt to obtain data about the real dimension of the seropositivity for anti-Trypasonoma cruzi antibodies in the region, the authors carried out a large-scale study on 45,774 serum samples from blood donors of the Hemocentro of Hospital Universitário Regional do Norte do Paraná (HURNP), Universidade Estadual de Londrina. The immunological tests were done at the Division of Clinical Immunology of HURNP from May 1990 to December 1994. The serum samples were studied by the indirect hemagglutination assay (IHA, using kits commercially obtained from EBRAM) and by indirect immunofluorescence (IFI, using kits from LIO SERUM) with anti-human IgG conjugate (LABORCLIN). The results demonstrated that 643 serum samples were positive in both assay corresponding to a seroprevalence of 1.4%, i.e., a significant decrease in anti-Trypanosoma cruzi antibodies in the region in comparison with the previously mentioned rates. Data correlating sex and age of seropositive blood donors are presented, as well as the possible factors that may have contributed to the results observed.