Lack of acute pathogenicity and toxicity in mice of an isolate of Metarhizium anisopliae var. anisopliae from spittlebugs.

A monospore strain of Metarhizium anisopliae var. anisopliae (EH-479/2), isolated in Mexico from Aeneolamia sp., was tested for oral acute intragastric pathogenicity and toxicity in CD-1 mice, including a thorough histological study. Animals were inoculated by gavage with one dose (10(8) conidia/animal) of viable (72 mice) and nonviable (24 mice) conidia and compared to 18 control mice. Clinical observations were done daily; mycological and histological tests were performed during necropsies at days 3, 10, 17, and 21 after the inoculation. At the end of the study, no mice showed clinical symptoms of illness, and the animals' mean weight corresponded to that of healthy adults. No inflammatory reactions were identified in analyzed organs, suggesting the nonimmunogenic status of this fungal strain. Evidence of fungal germination was noted in two lymph nodes and in liver and lung of one dead mouse, out of 72 viable-conidia treated mice. There was no evidence of toxicity symptoms in mice inoculated with nonviable conidia. The results obtained support the nonpathogenic and nontoxic status of this fungal strain when administered in a sole intragastric dose in mice.

[Infectivity of the entomopathogenic fungus Verticillium lecanii in mice and guinea pigs]. / Infectividad del hongo entomopatógeno Verticillium lecanii en ratones y cobayos.

The resistance of plague insects to chemical insecticides as well as the importance of a healthy environment demands an alternative for agricultural plagues. Among others, biological control seems an alternate strategy with fungal entomopathogens playing a relevant role. The hyphomycete Verticillium lecanii is a natural bioregulator of aphids, scales and white-flies that attack different agricultural plantations. Its use in biological control programs must be assessed previously by safety procedures such as its innocuity in mammals and useful animals and plants. The aim of this study was pointed at demonstrating the innocuity of V. lecanii in mice and guinea pigs. Two strains of the fungus were injected intraperitoneally (10(8) conidia/kg of animal weight) to 130 mice and 66 guinea pigs. Two control groups were included, one injected with heat-killed fungi and the other with sterile physiological saline. The animals were killed at 8, 30 and 70 days after infection, and mycological and histopathological studies performed in their organs. Negative results obtained with the live fungus in the same manner as the two control groups, suggest the innocuity of V. lecanii in mice and guinea pigs.

[Exoenzymes of dermatophytes isolated from acute and chronic tinea]. / Exoenzimas de dermatofitos aislados de tiñas agudas y crónicas.

The presence of five enzymes (deoxyribonuclease, elastase, lipase, caseinase and hemolysin) in 76 strains of dermatophytes 47 of Trichophyton rubrum, 10 of T. mentagrophytes, five of T. tonsurans, 10 of Microsporum canis and four of Epidermophyton floccosum) isolated from 30 cases of acute dermatophytosis and from 46 chronic ones was determined by a qualitative plate assay; in the same way, the presence of these five enzymes with the acute and chronic dermatophytosis was correlated. It was observed that three of the enzymes were produced by the strains with a meaningful frequency; deoxyribonuclease was produced by 84.2% of the strains; elastase by 82.9%; and lipase by 65.8%. In T. rubrum the DNase was produced in 100% of strains. DNase and elastase were related to fungi which caused acute or chronic dermatophytosis in 93.3/78.2% and 96.6/74% respectively. On the other hand, lipase was present in 76% of strains, the ones that caused the chronic infections.

Immunological separation of Entomophthorales genera.

Exoantigens from Erynia neoaphidis, Conidiobolus major, C. thromboides, C. obscurus, Zoophthora radicans, and Basidiobolus ranarum were obtained from culture filtrates of fungal material grown in a yeast extract, peptone dialysate, dextrose medium and were tested against specific hyperimmune antisera prepared from E. neoaphidis, C. major, C. thromboides, and B. ranarum by the immunodiffusion technique. Specific precipitins were observed for E. neoaphidis and B. ranarum, while cross-reactions were detected among C. major, C. thromboides, and C. obscurus. The results suggest that genera of Entomophthorales can be easily separated by this simple immunological procedure.

Dermatophytes isolated from laboratory animals.

In order to determine the presence of dermatophytes in healthy skin, 200 animals from the animal house of Faculty of Medicine, U.N.A.M., were studied; these were 50 rats, 50 rabbits, 50 mice, and 50 guinea pigs. Out of these 200 animals, 29.5% had positive isolation of Trichophyton mentagrophytes, var. lacticolor. The frequency variation was: rats 68%; rabbits, 36%; mice, 8%; and guinea pigs, 6%. Male rats and male rabbits, had the higher incidence of positives. The epidemiologic repercussion of these and the significance to use these animals in biomedical investigation is discussed.

[Study of the pathogenicity of Conidiobolus coronatus in experimental animals]. / Estudio de la patogenicidad de Conidiobolus coronatus en animales de experimentacion.

The pathogenicity of a strain of Conidiobulus coronatus isolated from Aenolamia postica was investigated in 152 mice, 42 guinea pigs and 47 hamsters. Four routes of inoculation were used: intraperitoneal, subcutaneous, intratracheal and scarification in the oral mucosa. Each animal was inoculated 3 times at 3 week intervals. Animals were sacrificed at 1, 8, 15, 45 of 225 days after the first inoculation. Observations of macroscopic lesions (nodules, abscesses, adhesions, etc.) direct examinations, cultures and histopathological studies of different tissues were performed. The aforementioned lesions of tissue were the most frequently found and all of them were resolved by spontaneous cure. The animals inoculated intraperitoneally and subcutaneouslly presented the highest number of postive results. The histopathological features at the 1st and 8th days after inoculation showed an acute inflamatory infiltrate with well preserved fungus filaments; at the 15th day granulomas with giant cells were observed containing fragmented and disintegrated fungal hyphae; at the 45th and 225th days a fibrosis reaction was observed and no fungal filaments, could be found. In no animal was rhinoentomophthoromycosis never reproduced, and according to these results it is considered that either this strain is not a pathogen or its pathogenicity is very low.