Pathological changes in masked palm civets experimentally infected by severe acute respiratory syndrome (SARS) coronavirus.

Masked palm civets are highly susceptible to infection with the severe acute respiratory syndrome coronavirus (SARS-CoV). Infected animals become less aggressive and develop pyrexia, lethargy and diarrhoea. The present study describes the spectrum of histopathological changes in the lung, spleen, lymph node, liver, small intestine, kidney and cerebrum of civets infected experimentally with SARS-CoV.

Direct evidence of reassortment and mutant spectrum analysis of a very virulent infectious bursal disease virus.

The complete genomic sequence of very virulent infectious bursal disease virus (vvIBDV) Gx strain was determined, including the sequences of segment A, encoding the precursor polyprotein, and segment B, encoding the viral RNA polymerase (VP1) and 5'- and 3'-untranslating regions. Alignment of segment A of Gx with the sequences of 12 other vvIBDV strains showed 97.5% to 99.

Construction and characterization of porcine circovirus type 2 carrying a genetic marker strain.

Porcine circovirus type 2 (PCV2) is the primary causative agent of post-weaning multisystemic wasting syndrome in pigs. To generate a genetic marker strain of PCV2, the full-length genome of the virus was amplified using PCR, and two copies of the genome were ligated in tandem to construct an infectious molecular clone. A Sal I restriction enzyme site was inserted into the clone as a genetic marker, and the recombinant plasmid was transfected into porcine kidney cells to generate mutant virus.

Changes in VP3 and VP5 genes during the attenuation of the very virulent infectious bursal disease virus strain Gx isolated in China.

A very virulent infectious bursal disease virus (vvIBDV) Gx strain with high pathogenicity was attenuated through replication in specific-pathogen free (SPF) chicken embryos and in chicken embryo fibroblast (CEF) cell cultures. The changes in nucleotide sequences and the deduced amino acid sequences of VP3 and VP5 genes during attenuation were obtained. Sequence analysis of selected passages from numbers 0 to 20 in CEF's (designated here Gx to CEF-20) showed that there were no amino acid changes detected in the VP3 and VP5 genes before CEF-9.

Preparation and evaluation of anti-SARS coronavirus IgY from yolks of immunized SPF chickens.

Severe acute respiratory syndrome (SARS) is a recently discovered viral disease, characterized by fever, cough, acute fibrinous pneumonia and high infectivity. Specific pathogen-free (SPF) chickens were immunized with inactivated SARS coronavirus and their eggs were harvested at regular intervals. Yolk immunoglobulin (IgY) was extracted using the water dilution method, followed by further purification on a Sephadex G-75 column.