Clinical signs caused by P1 infection were usually visible as tan-to-purple inguinal lymph nodes.

<p>Clinical signs caused by P1 infection were usually visible as tan-to-purple inguinal lymph nodes.</p

Growth curves of P1 virus in PK-15 cells.

<p>Intracellular virus (▪) and extracellular virus(⧫).</p

Electron micrographs of P1 particles, obtained from CsCl density gradients, and negatively stained with phosphotungstic acid.

<p>(A) Without addition of antiserum. Note the virus particles dispersed at random. (B) Exposure to anti-P1 antiserum generated in rabbit: antibody bridges link the P1 particles.</p

Immunochemical staining of PK15 cells transfected with rpSK-2P1.

<p>(A) or rpSK-P1 (B) or empty pSK (C) or untransfected cells were used (D). The presence of P1 antigen is indicated by blue-purple staining.</p

Histological patterns in different tissues of the pigs.

<p>(A) Brain of a P1-inoculated pig. Note subarachnoid arterioles and capillaries telangiectasias with a large number of red blood cells. (B) Microscopic section of a pig lung. Note interstitial pneumonia characterized by greatly thickened interlobular septum and alveolar septal thickening, a small number of alveolar septum fractures, some expansion of the alveoli filled with red blood cells. (C) Myocardial cells showed atrophy of a mild degree. (D) Note swelling of the bladder muscle cells (E) Histiocytic hyperplasia of follicles in the tonsils of the inoculated pigs. (F) Haemorrhage of the inguinal lymph nodes observed in P1 plasmid DNA transfected pigs characterized as erythrocyte infiltration and haemosiderin deposition in the expanding medullary sinus. HE staining was used for all panels. Magnification. ×40.</p

Schematic diagram of the P1 molecular DNA clones constructed.

<p>Schematic diagram of the P1 molecular DNA clones constructed.</p

Detection of tissue distribution of P1 by PCR in infected and control pigs.

<p>Detection of tissue distribution of P1 by PCR in infected and control pigs.</p

Detection of viremia (P1 DNA) by PCR in sera of infected and control pigs.

<p>Detection of viremia (P1 DNA) by PCR in sera of infected and control pigs.</p