Pathological Diagnoses and Whole-genome Sequence Analyses of the Jaagsiekte Sheep Retrovirus in Xinjiang, China / 病毒学报

To carry out pathologic diagnoses and whole-genome sequence analyses of the Jaagsiekte sheep retrovirus (JSRV) in Xinjiang, China, we first observed sheep suspected to have the JSRV. Then, the extracted virus suspension was observed by transmission electron microscopy (TEM). Total RNAs from lungs of JSRV-infected sheep were extracted and reverse-transcribed using a cDNA synthesis kit. Six pairs of primers were designed according to the exogenous reference virus strain (AF105220). Reverse transcription-polymerase chain reaction was carried out from JSRV-infected tissue, and the whole genome of the JSRV sequenced. Our results showed: flow of nasal fluid ("wheelbarrow test"); different sizes of adenoma lesions in the lungs; papillary hyperplasia of alveolar epithelial cells; alveolar cavity filled with macrophages; dissolute nuclei in central lesions. TEM revealed JSRV particles with a diameter of 88 nm to 125. 4 nm. The full-length of the viral genome sequence was 7456 bp. BLAST analyses showed nucleotide homology of 96% and 95% compared with that of the representative strain from the USA (AF105220) and UK (AF357971). Nucleotide homology was 89.8% and 89.9% compared with the endogenous Jaagsiekte sheep retrovirus, Inner Mongolia strain (DQ838493) and USA strain (EF680300). The specific pathogenic amino-acid sequence "YXXM" was found in the TM district, similar to the exogenous JSRV: this gene has been reported to be oncogenic. This is the first report of the complete genomic sequence of the exogenous JSRV from Xinjiang, and could lay the foundation for study of the biological characteristics and pathogenic mechanisms of the pulmonary adenomatosis virus in sheep.

Cloning and sequencing analyses of the complete genome of the provirus of the Inner-Mongolia pandemic strain of the Jaagsiekte sheep retrovirus / 病毒学报

To investigate the kinship between the Inner Mongolia pandemic strain and representative strains of the Jaagsiekte sheep retrovirus (JSRV), total DNA from the lung tissue of a JSRV-infected sheep in Inner Mongolia was used to clone fragments of gag, pro and pol genes. The recombinant plasmid pMD-JSRV (including complete genomic sequence of the JSRV strain isolated from Inner Mongolia) was constructed by linking all the cloned fragments with long terminal repeat (LTR) and env gene fragments (cloned previous and reserved by our research team). Sequence analyses revealed that the genome was 7690 bp in length and contained several typical molecular markers for exogenous form of JSRV. These included the Sca I restriction site in the gag gene, two predicted "CCHC" motifs of zinc finger in the encoded nucleocapsid protein and the predicted "YXXM" motif in the TM region of Env. Homology analyses showed that the virus strain belonged to the JSRV type II. pMD-JSRV and AF105220 strains shared a nucleotide identification of 95%. The full length genomic clone of JSRV could provide a molecular basis for an infectious JSRV molecular clone as well as an experimental platform to study the detection and pathogenesis of JSRV.

Morphopathological study of naturally occurring ovine pulmonary adenocarcinoma in sheep in Fars province, Iran

Ovine pulmonary adenocarcinoma [OPA] is a contagious and transmissible lung cancer of sheep resembling human bronchiolo-alveolar carcinoma. In the present study, lungs of 9400 sheep slaughtered in Fars province, Iran were examined morphopathologically. The OPA was diagnosed in the lungs of 21 [0.22%] out of 9400 sheep. Frequency of involvement of different lobes in the affected lungs was included apical lobe [62%], cardiac lobe [33%], middle lobe [33%], diaphragmatic lobe [62%] and accessory lobe [5%]. In 12 sheep, the classical form observed as firm, white to grayish coalescing masses mostly in the cranio-ventral lobes associated with wet cut surface and frothy fluid in the airways. In 9 sheep, atypical lesions observed as small clearly demarcated nodules mostly in diaphragmatic lobes associated with dry cut surface and minor fluid in the airways. Histopathological changes were almost similar in the two forms. They consisted of an acinar or papillary growth of neoplastic cells in the alveoli and polypoid proliferation of bronchiolar epithelium. There were variable amounts of connective tissue, myxomatous foci and infiltration of lymphocytes and plasma cells in the interstitial tissue of the affected alveoli. No metastatic lesion was observed in the lymph nodes. The findings of this study show that atypical and classical forms represent different stages or manifestations of a single disease spectrum

A specific PCR assay and a nested PCR assay for the screening of ovine pulmonary adenomatosis / 病毒学报

Ovine pulmonary adenomatosis (OPA) is a naturally occurring contagious lung tumor of sheep which was caused by an exogenous retrovirus of sheep, jaagsiekte retrovirus (JSRV). Although no specific circulating antibodies against the virus coud be detected in infected sheep, exogenous JSRV proviral DNA sequences (exJSRV) and JSRV RNA transcripts could be detected in lung tumors, lymphoreticular system and peripheral blood mononuclear cells (PBMC) from sheep affected by OPA. The sheep genome carried 15 to 20 copies of endogenous retrovirus loci (enJSRV) that were similar to JSRV in structural genes but the divergene in U3. Therefore, primers specific for the U3 sequences of exJSRV were designed for the specific PCR and nested PCR (n-PCR). Sensitivity between specific PCR assay and n-PCR assay was compared by using serial dilutions of positive plasmid pJSRV-LTR in a background of 700ng sheep genome DNA. Sensitivity of n-PCR was ten-fold higher than specific PCR. The n-PCR was only available in blood test for detection of JSRV infected sheep and might be useful in epidemiological studies and disease control of OPA.