Adriana Méndez-Bernal

Rhabdomyosarcomas are rarely reported in reptiles, and this is, to the authors′ knowledge, the second one described in a tortoise. A male captive terrestrial tortoise of at least 11 years of age ( Gopherus berlandieri ) was presented with a reddened growth of the distal aspect of the right posterior limb, measuring approximately 4.5 cm. The affected limb was amputated, and radiologic evaluation of the sample revealed osteolysis of the phalanges and peripheral inflammation. Initial histopathologic examination showed a nonencapsulated, high cellularity neoplastic lesion conformed by poorly differentiated cells with unappreciable or scant cytoplasm and a nucleus with one or two prominent nucleoli. Occasionally, bigger, eosinophilic, strap cells with evident cross‐striations were present and stained red by Masson′s trichrome stain. The tissue resulted negative for immunohistochemistry staining with MyoD1 and myogenin markers, yet transmission electron microscopy showed electron‐dense bands compatible with Z‐band remains which constitutes a high certainty criterion for the diagnosis of rhabdomyosarcomas. This case highlights the advantages of ultrastructural studies over the more commonly performed immunohistochemistry studies in the diagnosis of neoplasia in nondomestic animals.

A short‐tailed female bat ( Carollia perspicillata ), 1 year old, died without apparent signs of the disease while on display at an amusement park in the Municipality of Montemorelos, Nuevo León, Mexico. Amphophilic nuclear inclusion bodies were observed in the intestinal epithelia, corresponding to the virus of the adenovirus genera. Although there have been no reported adenovirus cases of this bat species in Mexico, through an anatomopathological study and support from the microscopic, ultrastructural, and molecular findings of intestinal lesions, a diagnosis of enteritis caused by Adenovirus Type 2 was made. To the authors’ knowledge, the case described herein is the first report of infection by Adenovirus Type 2 in a short‐tailed bat in Mexico.

Exosomes are extracellular microvesicles of endosomal origin (multivesicular bodies, MVBs) constitutively released by eukaryotic cells by fusion of MVBs to the plasma membrane. The exosomes from Leishmania parasites contain an array of parasite molecules such as virulence factors and survival messengers, capable of modulating the host immune response and thereby favoring the infection of the host. We here show that exosomes of L. mexicana amastigotes (aExo) contain the virulence proteins gp63 and PP2C. The incubation of aExo with bone marrow‐derived macrophages (BMMs) infected with L. mexicana led to their internalization and were found to colocalize with the cellular tetraspanin CD63. Furthermore, aExo inhibited nitric oxide production of infected BMMs, permitting enhanced intracellular parasite survival. Expressions of antigen‐presenting (major histocompatibility complex class I, MHC‐I, and CD1d) and costimulatory (CD86 and PD‐L1) molecules were modulated in a dose‐dependent fashion. Whereas MHC‐I, CD86 and PD‐L1 expressions were diminished by exosomes, CD1d was enhanced. We conclude that aExo of L. mexicana are capable of decreasing microbicidal mechanisms of infected macrophages by inhibiting nitric oxide production, thereby enabling parasite survival. They also hamper the cellular immune response by diminishing MHC‐I and CD86 on an important antigen‐presenting cell, which potentially interferes with CD8 T cell activation. The enhanced CD1d expression in combination with reduction of PD‐L1 on BMMs point to a potential shift of the activation route towards lipid presentations, yet the effectivity of this immune activation is not evident, since in the absence of costimulatory molecules, cellular anergy and tolerance would be expected.