Construction of a molecular clone of ovine enzootic nasal tumor virus.

BACKGROUND: Enzootic nasal tumor virus (ENTV-1) is an ovine betaretrovirus that has been linked to enzootic nasal adenocarcinoma (ENA), a contagious tumor of the ethmoid turbinates of sheep. Transmission experiments performed using virus isolated from cell free nasal tumor homogenates suggest that ENTV-1 is the causative agent of ENA; however, this etiological relationship has not been conclusively proven due to the fact that the virus cannot be propagated in vitro nor is there an infectious molecular clone of the virus. METHODS: Here we report construction of a molecular clone of ENTV-1 and demonstrate that transfection of this molecular clone into HEK 293T cells produces mature virus particles. RESULTS: Analysis of recombinant virus particles derived from the initial molecular clone revealed a defect in the proteolytic processing of Gag; however, this defect could be corrected by co-expression of the Gag-Pro-Pol polyprotein from the highly related Jaagsiekte sheep retrovirus (JSRV) suggesting that the polyprotein cleavage sites in the ENTV-1 molecular clone were functional. Mutagenesis of the molecular clone to correct amino acid variants identified within the pro gene did not restore proteolytic processing; whereas deletion of one proline residue from a polyproline tract located in variable region 1 (VR1) of the matrix resulted in production of CA protein of the mature (cleaved) size strongly suggesting that normal virion morphogenesis and polyprotein cleavage took place. Finally, electron microscopy revealed the presence of spherical virus particles with an eccentric capsid and an average diameter of about 100 nm. CONCLUSION: In summary, we have constructed the first molecular clone of ENTV-1 from which mature virus particles can be produced. Future experiments using virus produced from this molecular clone can now be conducted to fulfill Koch's postulates and demonstrate that ENTV-1 is necessary and sufficient to induce ENA in sheep.

Subtipos de virus del papiloma humano y lesiones intraepiteliales e invasoras de cérvix uterino en mujeres de la provincia de Ciudad Real / Subtypes of human Papillomavirus and intraepithelial invasive lesions of the uterine cervix in women in the area of Ciudad Real

Introducción: El papel oncogénico dei virus dei papíloma humano (VPH) en las lesiones intraepiteliales de cérvix uterino se ha descrito en numerosas publicaciones. Objetivo: Conocer la prevalencia y los subtipos de infección por VPH en pacientes con lesiones citológicas. Material y métodos: Durante dos años se han diagnosticado las triples tomas citológicas de 6300 mujeres. En todas las lesiones intraepiteliales y carcinomas invasores se determinó la presencia de ADN vírico dei VPH mediante reacción en cadena de polimerasa (RCP). Resultados: El VPH fue positivo en el 20 por ciento de las lesiones de bajo grado, en el 73 por ciento de las de alto grado y en el 50 por ciento de los carcinomas invasores. El subtipo más frecuente en lesiones de bajo grado fue "no upado". El subtípo 16 se asoció a lesiones de alto grado y a carcinoma invasor. En cuatro ocasiones se aisló más de un subtípo de VPH. Conclusiones: Los subtipos de VPH aislados son similares a los descritos en nuestro medio (AU)

Detection of type C virus particles in Japanese monkeys seropositive to adult T-cell leukemia-associated antigens.

Type C virus particles which were identical to adult T-cell leukemia virus (ATLV) in morphology were detected in phytohemagglutinin-stimulated peripheral lymphocytes from four out of four Japanese monkeys seropositive to adult T-cell leukemia-associated antigens. It is possible that non-human primates may be a natural reservoir of ATLV, and vector-borne transmission of ATLV from monkeys to humans should be explored.

Oral condyloma acuminatum. A case report with light microscopic and ultrastructural features.

A case of intraoral condyloma acuminatum with clinical, light microscopic, and ultrastructural features is presented. The presence of intranuclear virus particles is demonstrated by electron microscopy. To the best of our knowledge, the presence of viruses has not previously been reported in the oral lessions of this disease.

A marsupial oncovirus?

A virus-like particle was observed in two continuous cell lines derived from the marsupial Sminthopsis crassicaudata (Fat-tailed Dunnart). The development of the particle was similar to the development of D-type oncoviruses. Initially, a crescentof nucleoid material was observed near the nucleus in the region of the Golgi apparatus. This crescent developed into a doughnut-shaped-A-type particle which migrated through the cytoplasm towards the cell membrane where it budded either into a smooth membrane cytoplasmic vacuole or from the cell membrane. Only enveloped A-type particles were observed; no mature B-type, C-type or D-type particles were detected.

Retrovirus-like particles in EBV-negative Burkitt's lymphoma cell line but not in EBV-DNA-positive lines from patients with ataxia telangiectasia and Down's syndrome.

Retrovirus-like particles can be recovered by arginine deprivation from the BJAB-1 Epstein-Barr virus (EBV) negative cell line derived from an African patient with typical Burkitt's lymphoma. These particles resemble retroviruses in their morphology and in their physicochemical properties. Particles with a similar morphology were obtained from derivative cell lines established by infecting BJAB-1 cells with EBV. On the other hand, retrovirus-like particles could not be induced in EBV-DNA-positive lymphoblastoid cell lines derived from non-leukaemic patients with ataxia telangiectasia and Down's syndrome and from a patient with infectious mononucleosis.

Glioblastoma multiforme: morphology and biology.

Glioblastoma multiforme, representing about 50% of all gliomas, encompasses a group of intrinsic tumours of the brain in later years (age peak around 50 years), the morphological hallmarks of which are an ensemble of variations in tumour cell and tissue structure featuring its biological malignancy. Glioblastoma, while sometimes appearing as a distinct "primary" tumour type, is usually accepted as an extreme manifestation of anaplasia and dedifferentiation of glia, mostly astrocytic. The astrocytic nature of most glioblastomas has been confirmed by ultrastructural studies and progressive differentiation of tumours maintained in organotypic tissue culture. Reproducible experimental models are particularly induced by oncogenic RNA (oncorna) viruses. The cell kinetic parameters are similar to those of other solid malignant tumours except for a comparatively low growth fraction of glioblastoma. The frequent occurrence of giant cells as well as of regressive changes with necrosis and vascular responses are indirect (secondary) indicators of malignancy which coincide with histochemical (enzymatic anisochronia) and biochemical data (lower level of glia specific S100 protein than in differentiated gliomas). Vascular proliferation, a characteristic feature of glioblastoma, may occasionally progress to sarcomatous transformation with development of gliosarcomas (mixed glial-mesenchymal tumours). While dissemination of glioblastoma through the cerebrospinal pathways is not uncommon, extraneural distant metastatic spread is rare, and usually observed after craniotomy. The results of modern neuro-oncology support the pathogenetic view that glioblastoma results from neoplastic transformation of glial elements with continuing dedifferentiation. This transformation can be experimentally induced by various factors including oncogenic DNA (oncorna) viruses by using a reverse transcriptase, while there is indirect evidence for an oncorna-virus information in human glioblastoma. The significance of immunological factors in the pathogenesis of brain tumours and in the course of neoplastic transformation of glia is not yet understood, but both morphological and immunological data are in favour of a cell mediated immunological reaction against tumour-specific antibodies. Since immunological factors and changes in cytokinetics are apparently active after the transformed tumour cells proliferate, all available therapeutic methods, including radiation, chemotherapy, and immunotherapy of glioblastoma only influence the final stages of neoplastic development with clinical manifestation of the tumour. In spite of modern combination and multimodality therapy schemes the prognosis of glioblastoma is still poor.

Oncornavirus-like particles in squirrel monkey (Saimiri sciureus) placenta and placenta culture.

Oncornavirus-like particles similar in morphology to type D particles were observed in 1 of 2 squirrel monkey (Saimiri sciureus) placentas. Intracytoplasmic type A particles, immature virus particles, and mature viruses with eccentric or occasionally centric nucleoids were associated with placental syncytiotrophoblasts. A spike layer typical of type B viruses was not detected in viral envelopes. Onvornaviruses, identical to those previously isolated from squirrel monkey tissues and similar to Mason-Pfizer monkey virus, were seen in cultures derived from the virus-positive squirrel monkey placenta cocultivated with a mink lung culture. The major morphologic difference between the in vivo and the in vitro squirrel monkey virus was in the nucleoid position of mature virus particles.

Ultrastructure of human prostatic epithelium. Secretion granules or virus particles?

The objective of this report is to demonstrate that only slight and superficial similarities exist between true virus particles and secretion granules in human prostatic epithelium. In spite of this, secretion granules have sometimes been called virus or virus-like particles. With the current interest in the possible role of viruses in the etiology of some human cancers, many investigations are in progress in search of human tumor viruses. The presence of RNA virus particles in normal as well as tumor tissues derived from animals and man, further complicates the picture. Also, in view of the fact that recent studies indicate an association between herpes simplex type 2 virus and cervical cancer, the possibility of the involvement of the same virus, which has a venereal mode of transmission, in prostatic and other genitourinary cancers in the human male has been considered. Investigators with peripheral interests in such studies are cautioned against making quick decisions on the nature of the "virus-like particles" often observed in secretory cells because these particles often happen to be cell organelles.