Search

Search Results

• CHARACTERIZATION OF KTY-06 FIELD PRRS STRAIN ISOLATED IN VIETNAM AND EVALUATION OF ANTIBODY PRODUCING OF THE INACTIVATED VIRUS IN PIG

  Nguyen Thi Lan, Trinh Dinh Thau, Yamaguchi Ryoji, Nguyen Van Giap, Luong Quoc Hung, Nguyen Thi Yen, Nguyen Huu Nam, Nguyen Thi Hoa

  Date Received: 01-09-2016 / Date Accepted: 30-11-2016 / Date Published: 02-07-2025

   Abstract PDF (VIETNAMESE)

  KTY-06 virus strain was isolated from 2-week-old piglet in a PRRS outbreak in Northern Vietnam in 2015 that had clinical signs, gross findings, and microsopic lesions specific with HP-PRRS. Results of a phylogenetic analysis of the open reading frame 5 region of the KTY-06 strain showed it to be a North American genotype and classified into sublineage 8.7, in which highly pathogenic Chinese PRRSV strains are also clustered. Passaging in Marc-145 cells, KTY-06 gradually induced 35% up to 100% CPE between 36 to 60 hours post inoculation. The titer of KTY-06 was 1.74 x 105 TCID50/25µl. Of which, titer of the free viruses in the supernatant was higher than the titer of the cell associated virusese. Formalin-inactivated KTY-06 was able to stimulate pigs to produce specific antibodies against PRRSV. The immune response was detectable 14 day post immunization (dpi) (S/P ratio was 0.697 ± 0.271), peaked at 42 dpi (S/P ratio was 1.197 ± 0.256), and then declined at 49 dpi. The results suggest that KTY-06 was a candidate for strain selection for producing PRRS vaccine.

  DOI: https://doi.org/10.31817/tckhnnvn.2016.14.10.

• Biological Characteristics of PRRSVirus Strain Kty-Prrs-05 Isolated in Vietnam through Cultured Passages

  Le Thi Toan, Nguyen Huu Nam, Pham Hong Ngan, Le Van Hung

  Date Received: 23-02-2016 / Date Accepted: 03-05-2016

   Abstract PDF (VIETNAMESE)

  The PRRSV strain studied in this research was KTY-PRRS-05, isolated from pigs carrying “blue ear” disease (PRRS) from Haiphong city, Vietnam. The cell line of MARC-145 was suitable to isolate PRRS virus. Virus quickly replicated in such cells and caused typical cytopathogenic effect (CPE), i.e cells clumped and sloughed from the bottoms of culture flask. PRRS virus caused CPE in MARC-145 cells as early as 24 hours post inoculation (hpi); after 84hpi, almost of cells were detached from surface of the culture flasks. Viral load could get 105 TCID50/25́l) in each sub-culture passage. Viral load freely released in medium was higher than that inside cells. The viral titer multiplied in MARC-145 cells increased continuously at 48 hours post inoculation, then maximized at 72 hours withlog10 TCID50 of 4,83. In the present research, some biological characteristics, including CPE, viral load, and the growth curve of PRRSV isolates (KTY-PRRS-05) were identified and compared with those of vaccine virus. These results are useful for selecting PRRS virus in production of PRRS vaccine or antigen in development of test kit for diagnosis.

• Study on Some Biological and Molecular Biological Characteristicsof the KTY-PRRS-01 Virus Strain Isolated in Vietnam

  Pham Van Son, Nguyen Thi Lan, Nguyen Van Cam, Nguyen Ba Hien

  Date Received: 27-02-2017 / Date Accepted: 25-04-2017

   Abstract PDF (VIETNAMESE)

  The study was carried out on the KTY-PRRS-01 virus strain isolated in Vietnam. The PRRSV strains were cultured for 5thconsecutive generations on the Marc145 cell and in each passage the virus was tested for biology and molecular biology characteristics. The results of the study showed that through 5th passages, the ability to multiply and destroy the cells of the original virus over time had no significant difference in the generations. The virus began to multiply and had cytopathogenic effect after 48 hours post - infection, cytopathogenic effect reached 80% at 72 hours post - infection, and the cells were completely destroyed after 84 hours post - infection. TCID50 of virus was stable through 5th passages with a titre from 3,03x106/ml to 7,12x106/ml. The ORF5 and ORF7 gene sequences of the virus strain through 5th passages were sequenced. Sequences of these genes showed no difference in nucleotide sequences as well as amino acids through 5th passages. Thus the KTY-PRRS-01 virus strain is stable in biological and molecular biology characteristics over 5th passages.