12 research outputs found
PRRSV: Study of in vivo cell tropism and virus-induced apoptosis by in situ detection techniques
We have extensively used the techniques of in situ hybridization
and immunohistochemistry to detect the cells and tissues that are targeted during
infection with pathogenic strains of PRRSV. We found some important exceptions to
the generally accepted concept that macrophages are the main or only type of cell
to be infected by PRRSV in vivo. In the lung, we found that pneumocytes type II of
the alveolae can become infected by PRRSV. Our most prominent finding regarding cell
tropism is the notion that PRRSV can infect important cells other than macrophages during
the pathogenesis of testicular infection. The testicular infection by PRRSV centers on two
types of cells: (i) epithelial germ cells of the seminiferous tubules, primarily spermatids
and spermatocytes, and (ii) macrophages, which are located in the interstitium of the testis.
Formation of multi-nucleated giant cells (MGCs) and abundant germ cell depletion and death
are observed. Importantly, by use of in situ TUNEL reaction we obtained evidence that
such germ cell death occurs by apoptosis. Simultaneously with these testicular alterations,
we have observed that there is a significant increase in the number of immature sperm cells
(mainly MGCs, spermatids and spermatocytes) in the ejaculates of PPRSV-inoculated boars,
that these cells are infected with PRRSV, and that in all likelihood are responsible for
the venereal transmission of PRRSV. We observed that the presence of PRRSV in semen ceases
when viremia subsides, thus suggesting that the hematogenous route (sp. blood-borne infected
macrophages) is the way in which testes are continuously seeded with PRRSV. In the female
gonad we found that there is a frank infection by PRRSV in macrophages of the atretic
follicles of the ovarium, and some minor involvement of stromal and granulosa cells.
Importantly, we did not find any evidence of ova infection and/or perpetuation of PRRSV
in these tissues or in the embryo, thus making the female gonad an unlikely site of
persistence. In our experience, the lymphoid tissues, including tonsils, have been
the most consistent site where the virus could be detected the longest. The apoptosis
caused by PRRSV in testes is massive and affects many more cells than those affected by
PRRSV infection. We extended our search for apoptosis to the most consistent target sites
of PRRSV, lung and lymphoid tissues, using in situ (immunohistochemistry for PRRSV antigens
and TUNEL reaction for apoptosis), biochemical (DNA electrophoresis for detection of DNA
fragmentation), and electron microscopy for ultra-structural morphologic studies. We
confirmed that PRRSV infection resulted in widespread apoptosis in the lungs and lymphoid
tissues of infected pigs. While the apoptosis affecting alveolar macrophages in the lungs
was easily recognizable, we suspect that apoptosis affects some other cells in the alveolae
and also in the germinal cells of the lymphoid tissue. As we had seen previously in testes,
virus infection-induced apoptotic cells were more abundant than PRRSV-infected cells in all
tissues. Again in this case double-labeling experiments demonstrated that the majority of
apoptotic cells did not co-localize with PRRSV-infected cells. Besides the direct apoptogenic
effect of PRRSV on the infected cell, our findings suggest the existence of an indirect
mechanism for the induction of apoptosis in non-infected, bystander cells. A direct effect
of the whole virus or one viral component (i.e. p25) at the level of the cell membrane
(without penetrating the cell) can not be ruled out at this time. However, it seems plausible
to us that apoptogenic cytokines (i.e. tumor-necrosis-factor, TNF) could be released in the
environment that surrounds the testicular seminiferous tubules, alveola of the lung or
germinal centers of lymph nodes. A putative source of these cytokines could be PRRSV-infected
macrophages, which besides being the most prominent cell in PRRSV-infected tissues, are
known to enhance the TNF secretion when infected by viruses
Pneumonia intersticial em bovinos associada à ingestão de batata-doce (Ipomoea batatas) mofada
Demodicose suína no norte do estado do Rio de Janeiro: relato de caso
Um leitão oriundo de um criatório do norte do estado do Rio de Janeiro, mantido no biotério do Hospital Veterinário da Universidade Estadual do Norte Fluminense Darcy Ribeiro e utilizado como caso piloto de projeto de pesquisa para investigações sobre o acesso videolaparoscópico retal (NOTES - Natural Orifice Translumenal Endoscopic Surgery), foi eutanasiado e necropsiado. Amostras do ponto de acesso do tubo de inserção na região mucocutânea anal foram colhidas, fixadas em formalina neutra tamponada a 10%, processadas por inclusão em parafina e coradas pela hematoxilina e eosina para histologia. Observou-se o comprometimento de folículos que, dilatados, exibiam formações que lembravam Demodex spp. cortados em vários sentidos e, por se tratar de ácaros espécie-específicos, concluiu-se como D. phylloides. Na citopatologia, o ácaro foi recuperado e identificado a fresco, mostrando-se alongado, com quatro pares de patas ventrais e no terço anterior do corpo. Este se refere ao primeiro registro de demodicose suína no estado do Rio de Janeiro