Replication of duck plague virus in artificially infected ducks detected by in situ hybridization / 病毒学报

Replication of duck plague virus(DPV) in artificially infected ducks were detected by in situ hybridization (ISH) which employed a 37bp oligonucleotide as probe designed according to DPV DNA sequence in GenBank. The results indicated that DPV DNA was detected in liver, intestine and bursa Fabricius at 4 h, in spleen and esophagus at 6h, in thymus at 12h post infection; DPV DNA in lung and kidney was detected only in dead ducks and no positive signal was detected in muscle, heart, cerebrum and pancreas. DPV DNA was distributed in cell nucleus and cytoplasm. Hepatocytes, sinus endodermal cells and Kuffer's cells were the mainly infected cell types in liver. DPV DNA was mainly detected in epithelium of villi, in lamina propria of intestinal villi of duodenum, in stratum spinosum of esophagus, and in epithelium, cortex, medulla of bursa Fabricius. The positive signals were mainly detected in medulla of thymus, lymphocytes and macrophages of spleen. The research suggests that ISH is a direct and specific method in detecting DPV DNA in paraffin sections and it's also a good method for virus diagnosis and DNA location of DPV.

Studies on porcine reproductive and respiratory syndrome virus morphogenesis in Marc-145 cell and the ultrastructural changes of the infected cells / 病毒学报

Electron microscopy was employed for ultrastructural observation of Marc-145 cells infected with porcine reproductive and respiratory syndrome virus (PRRSV) SC1 strain and studied the virus morphogenesis in infected cells. The results demonstrated that PRRSV was spherical and enveloped. The virion is 45-65 nm in diameter and its nucleocapsid was approximately 25-30 nm. PRRSV entered Marc-145 cells by endocytosis, and replicated in the cytoplasm. The mature viruses were released from infected cells by budding or exocytosis. The main ultrastructural changes of the infected cells were as follows: increased number of cytoplasmic vacuoles, dilated endoplasmic reticulum, mitochondria underwent hyperplasia with its ridges swollen, sloughed, and eventually vacuolated. Typical apoptosis was also observed in the infected Marc-145 cells, which included microvilli sloughing off the cell, appearance of apoptotic bodies and cell fragmentation.