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( Hoai Thu Dao ),( Van Tan Do ),( Quang Lam Truong ),( Tae-wook Hahn ) 한국미생물 · 생명공학회 2020 Journal of microbiology and biotechnology Vol.30 No.7
Actinobacillus pleuropneumoniae (APP) is a causative agent of porcine pleuropneumonia. Therefore, the development of an effective vaccine for APP is necessary. Here, we optimized the culture medium and conditions to enhance the production yields of Apx toxins in APP serotype 1, 2, and 5 cultures. The use of Mycoplasma Broth Base (PPLO) medium improved both the quantity and quality of the harvested Apx toxins compared with Columbia Broth medium. Calcium chloride (CaCl<sub>2</sub>) was first demonstrated as a stimulation factor for the production of Apx toxins in APP serotype 2 cultures. Cultivation of APP serotype 2 in PPLO medium supplemented with 10 μg/ml of nicotinamide adenine dinucleotide (NAD) and 20 mM CaCl<sub>2</sub> yielded the highest levels of Apx toxins. These findings suggest that the optimization of the culture medium and conditions increases the concentration of Apx toxins in the supernatants of APP serotype 1, 2, and 5 cultures and may be applied for the development of vaccines against APP infection.
Hoai Thu Dao,Quang Lam Truong,Van Tan Do,Tae-Wook Hahn 대한수의학회 2020 Journal of Veterinary Science Vol.21 No.2
Actinobacillus pleuropneumoniae (APP) causes a form of porcine pleuropneumonia that leads to significant economic losses in the swine industry worldwide. The apxIBD gene is responsible for the secretion of the ApxI and ApxII toxins and the pnp gene is responsible for the adaptation of bacteria to cold temperature and a virulence factor. The apxIBD and pnp genes were deleted successfully from APP serotype 1 and 5 by transconjugation and sucrose counter-selection. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants lost hemolytic activity and could not secrete ApxI and ApxII toxins outside the bacteria because both mutants lost the ApxI- and ApxII-secreting proteins by deletion of the apxIBD gene. Besides, the growth of these mutants was defective at low temperatures resulting from the deletion of pnp. The APP1ΔapxIBDΔpnp and APP5ΔapxIBDΔpnp mutants were significantly attenuated compared with wild-type ones. However, mice vaccinated intraperitoneally with APP5ΔapxIBDΔpnp did not provide any protection when challenged with a 10-times 50% lethal dose of virulent homologous (APP5) and heterologous (APP1) bacterial strains, while mice vaccinated with APP1ΔapxIBDΔpnp offered 75% protection against a homologous challenge. The ΔapxIBDΔpnp mutants were significantly attenuated and gave different protection rate against homologous virulent wild-type APP challenging.
Phylogenetic analysis of emerging infectious diseases in pigs and cattle during 2019-2022 in Vietnam
Van Tan Do,Hoai Thu Dao,Hung Vu Khac,Duc Tan Nguyen,Van Khien Do 강원대학교 산림과학연구소 2022 강원대학교 산림과학연구소 학술대회 Vol.2022 No.10
This work was conducted to review the phylogenetic of emerging viral infectious diseases in pigs and cattle during 2019- 2022 in Vietnam. Among of viral diseases in pigs, African swine fever (ASF) has caused the significantly economical lost. Analysis of the C-terminal end of p72 revealed that the ASFV strains in Vietnam belongs to genotype II, serogroup 8. The ORF5 sequence of the nineteen porcine reproductive and respiratory syndrome virus (PRRSV) isolates belonged to genotype 2. Among them, thirteen isolates belonged to lineage 8, together with the vaccine strain JAX1-R and isolates from Vietnam and China. One isolate was clustered into lineage 1 with isolates from Thailand. Phylogenetic analysis of porcine circovirus type 2 (PCV2) ORF2 from forty-three positive clinical samples showed that five isolates belonged to PCV2b and thirty-eight isolates belonged to PCV2d. A lumpy skin disease virus (LSDV) isolated in the first outbreak in Vietnam was 100% identical to viruses isolated in China (2019) based on the p32 and RP030 genes. These new findings are important for vaccine development to control these diseases in Vietnam.
Van Tan Do,Hoai Thu Dao,Tae-Wook Hahn 대한수의학회 2020 Journal of Veterinary Science Vol.21 No.6
A cold-adapted porcine reproductive and respiratory syndrome virus (CA-VR2332) was generated from the modified live virus strain VR2332. CA-VR2332 showed impaired growth when cultured at 37°C with numerous mutations (S731F, E819D, G975E, and D1014N) in the hypervariable region of the NSP2, in which the mutation S731F might play a vital role in viral replication at 30°C. Conserved amino acid sequences of the GP5 protein suggests that CA-VR2332 is a promising candidate for producing an effective vaccine against PRRSV infection. Further studies on replication and immunogenicity in vivo are required to evaluate the properties of CA-VR2332.
Van Tan Do,Quang Lam Truong,Hoai Thu Dao,Thi Lan Nguyen,Minna Shin,Kyeong Ryeol Shin,Tae-Wook Hahn 대한수의학회 2023 大韓獸醫學會誌 Vol.63 No.2
Porcine epidemic diarrhea (PED) is characterized by acute enteritis, watery diarrhea, weight loss, dehydration, and death, with high mortality in neonatal piglets. In this study, 3 virus isolates collected in Vietnam between 2016 and 2017 were propagated successfully in Vero cells at high virus titers. Sequence analysis of the fulllength spike (S) gene showed that all 3 isolates belong to genogroup 2b, which is closely related to other prevalent Asian strains. A comparison of the amino acid sequence revealed a 98.19% to 99.13% homology with the Vietnam isolates circulating during 2013–2015, suggesting that field PED viruses (PEDVs) are evolving continuously. Experiments in animals showed that the antisera from guinea pigs immunized with the vaccine strain resulted in higher levels (5 log2) of neutralizing antibodies against the homologous strain and a relatively moderate level of neutralizing antibodies against the field isolates. This finding would be helpful in selecting a PEDV strain for vaccine development.
Do, Van Tan,Truong, Quang Lam,Dao, Hoai Thu,Nguyen, Thi Lan,Kim, Jini,Hahn, Tae-Wook The Korean Society of Veterinary Science 2021 大韓獸醫學會誌 Vol.61 No.3
Porcine epidemic diarrhea (PED) is characterized by acute enteritis, watery diarrhea, weight loss, dehydration, and death with high mortality in neonatal piglets. In this study, 3 virus isolates collected in Vietnam between 2016 and 2017 were successfully propagated in Vero cells at high virus titers. Sequence analysis of the full-length spike (S) gene revealed that all 3 isolates belong to genogroup 2a, which is closely related to other prevalent Asian strains. Amino acid sequence comparisons revealed 98.19% to 99.13% homology with the Vietnam isolates circulating during 2013-2015, suggesting that field PED viruses (PEDVs) evolve continuously. Experiments in animals demonstrated that antisera from guinea pigs immunized with the vaccine strain resulted in higher levels (5 log<sub>2</sub>) of neutralizing antibody against the homologous strain, and showed a relatively lower level of neutralizing antibody against the field isolates. This finding would be helpful in choosing a PEDV strain for vaccine development.
Van Tan Do,Quang Lam Truong,Hoai Thu Dao,Thi Lan Nguyen,Jini Kim,Tae-Wook Hahn 대한수의학회 2023 大韓獸醫學會誌 Vol.63 No.1
Three isolates (HID9047, HID9048, and HID9049) were listed in the original text as belonging to subgroup 2a during phylogenetic analysis. However, it was later determined by adding PEDV reference strains that they actually belonged to subgroup 2b. Therefore, we retract the former article