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• Pathogenesis of Hp-Prrsv in Crossbred Wild Pigs through Experimental Innoculation

  Do Tien Duy, Nguyen Pham Huynh

  Date Received: 23-11-2018 / Date Accepted: 05-03-2019

   Abstract PDF (VIETNAMESE)

  The objective of this study was to examine the pathogenesis of highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) in crossbred-wild pigs through experimentally infected model. Twenty eight healthy crossbred-wild pigs, 42-49 day-old, originated from CSFV-PRRSV-negative farms were allocated in two experimental groups.The findings in clinical signs and pathology showed that the acute phase of infection took place from 5 to 14 days post infection. The major manifestations were fever, anorexia, respiratory failure, eye discharge and swelling, shivering and death. Severe interstitial pneumonia happened in all infected animals and interstitial pneumonia accompanied with hemorrhage recorded in died pigs. The laboratory indicators (viremia in the blood/tissues, IHC score, IgG antibodies, IL-1) were in homology with clinical pathology in acute phase of the disease. There were variations ofthe antigen distribution in various tissues over time-points post infection. This virus was first detected intheepithelial cells of bronchioles, stomach, kidney, bile duct and hepatic cells. The study results demonstrated that HP-PRRSV might cause severe pathology, wide antigenic distribution in visceral organs and could be fatal in crossbred-wild pigs through experimental infection.

• Study on the Virulence Factors ofVibrio parahaemolyticusCaused Acute Hepatopancreatic Necrosis Disease (AHPND) in Farmed WhiteLegShrimp (Litopenaeus vanamei) in Thua Thien Hue Province

  Nguyen Ngoc Phuoc, Nguyen Thi Xuan Hong, Nguyen Cong Chung

  Date Received: 13-03-2020 / Date Accepted: 24-04-2020

   Abstract PDF (VIETNAMESE)

  The aim of this study was to identified the virulence factors and the pathogenesis of Vibrio parahaemolyticusin farmed white leg shrimp in Thua Thien Hue province. In this study, 8 isolates of V. parahaemolyticuswas recovered from diseased white leg shrimp that showed typical clinical signs of AHPND such as pale-to-white hepatopancreas (HP), significant atrophy of the HP, softshells, guts with discontinuous, or no contents, black spots or streaks visible within the HP. The bacteria were identified as V. parahaemolyticusby using API 20E kit (BioMerieux). Four of 8 isolates have been detected that caused AHPND by using IQ Plus™ AHPND/EMS Plasmid Kit. Data of this study showed that the production of caseinase, phospholipase, haemolysin and mobility of these isolates were significantly stronger than others. The LD50 of isolate that caused AHPND was 105 cfu/mL. By contrast, experimental shrimp were healthy without any clinical signs and no mortality was observed in the treatment immersed in the isolate lacking toxin genes. This study showed strong relationship between virulence factors and pathogenesis of V. parahaemoliticus caused AHPND in shrimp.

• Application of Immunohistochemistry to Detect Antigen of African Swine Fever Virus in Infected Pigs

   Nguyen Thi Hoa, Truong Quang Lam, Hoang Thi Thu Hien, Nguyen Huu Nam, Lai Thi Lan Huong, Bui Tran Anh Dao, Yamaguchi Ryoji, Nguyen Thi Lan

  Date Received: 30-07-2020 / Date Accepted: 08-09-2020

   Abstract PDF (VIETNAMESE)

  The study was conducted to detect antigen of African swine fever virus (ASFV) in the tissues of infected pigs, therefore, contributing to clarifying the pathogenesis of the virus and providing a scientific basis for the selection of disease samples suitable for research and diagnostics. Nine organs of 5 ASFV positive pigs were collected and stained immunohistochemistry to detect viral antigen. Resultsshowed that the ASF virus antigen was highly concentrated in organs such as lymph nodes and spleen, the lungs, liver and kidney; followed by brain, heart, intestines and stomach.Antigenwas detected in macrophage cells, mononuclear cells in many different organs, hepatocytes and renal tubular epithelial cells.

• Detection of Virus-Like Particles (VLPs)inOtter Clam Spat (Lutraria philippinarumReeve, 1854)Colected from Hatchery

  Dang Thi Lua, Phan Thi Van, Nguyen Thanh Thuy

  Date Received: 25-09-2018 / Date Accepted: 29-01-2019

   Abstract PDF (VIETNAMESE)

  Swollen siphon disease has been considered as a serious threat to otter clam farming in Vietnam. Virus-like particles (VLPs) were identified asthe main causative agent of the disease, however, the transmission pathway and the pathogenesis of the disease has not been clarified yet. In this study, by using electron microscopy analysis, some host species such as otter clam spat and venerid clam (Tapes dorsatus) were selected to screen for the presence of VLPs and VLPs were further analyzed and described their size, structure and location in the host cells. The studies showed that VLPs were found in otter clam spat that were sampled from the hatchery. This finding indicated that the otter clam spat is one of the causes of spead of the wollen siphon disease in otter clam. VLPs have rod-like shape with the size ranging from 70-90 nm x 600-1.000 nm. They consist of outer shell, outer membrance, inner membrance, coreand are located in the cytoplasm of the host cells. Thesestudiesare playsed as scientific basis for developing strategies for classification of VLPs and control, prevetion and treatment of swollen siphon disease in otter clam.

• Gene Expresssion of Cytokine and Toll-like Receptor Signaling molecule mRNA in Peripheral Blood Mononuclear Cells (PBMCs) from Pigs Co-infected with Porcine Reproductive and Respiratory Syndrome Virus and Porcine Circovirus

  Dong Van Hieu, Phan Hong Dien, Tran Thi Huong Giang, Wen Bin Chung

  Date Received: 18-03-2015 / Date Accepted: 18-05-2015

   Abstract PDF (VIETNAMESE)

  Field and experimental studies have shown that co-infection of PRRSV and PCV2 in pigs were quite common and thus the interactions between both viruses in the host might be critical to the pathogenesis of the disease. The exact interaction mechanisms are unknown and remained to be elucidated. In this study, the expression of cytokine mRNA as well as Toll like receptor signaling molecules associated with innate immunity in peripheral blood mononuclear cells (PBMCs) from pigs infected with PRRSV and/or PCV2 were investigated. Cytokine mRNA and TLR signaling molecule expression were determined by quantitative real-time polymerase chain reaction. Co-infection of pigs with PRRSV and PCV2 led to up-regulated expression of IL-1β and IL-10 mRNA and down-regulated expression of TNF-α and IL-6, IFN-α and IFN-β in PBMCs of pigs co-infected with PRRSV and PCV2. An increased expression of CD14 mRNA was noticed in pigs co-infected with PRRSV and PCV2. A down-regulated expression of IRF-1 and IRF-3 mRNA might also suppress the expression of IFNs that leads to the enhanced replication of PCV2 in pigs co-infected with PRRSV and PCV2.