I. Background: ASFV causes a highly contagious hemorrhagic disease with a high mortality rates in domestic pigs. The virus has been isolated across various cell lines, but identifying a cell line to develop an effective commercial vaccine has been challenging which a major obstacle to effective vaccine development is identifying a commercial cell line that is suitable for high-yield viral replication.II. Methods and Results: The goal of this study was to identify a candidate commercial cell line for the replication of African swine fever virus (ASFV) by comparing several available cell lines with various medium factors. In the sensitivity test of cells, MA104 and MARC-145 had strong potential for ASFV replication. Next, MA104 cells were used to compare the adaptation of ASFV obtained from tissue homogenates and blood samples in various infectious media. At the 10th passage, the ASFV obtained from the blood sample had a significantly higher viral load than that obtained from the tissue sample (P = 0.000), exhibiting a mean Ct value = 20.39 ± 1.99 compared with 25.36 ± 2.11. For blood samples, ASFV grew on infectious medium B more robustly than on infectious medium A (P = 0.006), corresponding to a Ct value = 19.58 ± 2.10 versus 21.20 ± 1.47. ASFV originating from blood specimens continued to multiply gradually and peaked in the 15th passage, exhibiting a Ct value = 14.36 ± 0.22 in infectious medium B and a Ct value = 15.42 ± 0.14 in infectious medium A. However, there was no difference (P = 0.062) in ASFV growth between infectious media A and B when ASFV was cultured from tissue homogenates. III. Conclusions: A model was developed to enhance ASFV replication through adaptation to MA104 cells and the lack of mutation in serial culture passages may serve to maintain the immunogenicity of ASFV isolates when they are developed as vaccine candidates.

African swine fever (ASF) is a contagious haemorrhagic disease in pigs and has become endemic in several Vietnam provinces since the first outbreak in 2019. The presence of carriers and the recurrence of disease in the surviving swine herd after an ASF outbreak has not previously been properly evaluated. In this study, pigs naturally infected with an acute form of ASF were allowed to recover from the disease. A serological follow-up was conducted for more than 14 months with 14 convalescent gilts and their offspring. All convalescent animals had long lasting high serum antibody levels without persistent viremia. They also did not excrete virus via nasal discharge post-recovery.These convalescent pigs could partially perform as replacement gilts despite the fact that ASF affected reproductive performance. Here, we confirmed that there were neither the carriers of nor recurrence of disease in the convalescent pigs and their offspring following the outbreak of acute ASF. These findings may facilitate efforts to design a new farming model in ASF endemic provinces in Vietnam where there is a lack of a repopulation strategy due to the limited funding received from the local regulatory authorities.

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This quantitative study identifie factors affecting tourist perception in the context of rural tourism in Ca Mau province – the southernmost province of Vietnam, belonging to the Mekong Delta. In which, local culture, infrastructure and marketing communication has positive relation with tourist perception, while services & entertainment has negative relation. The research produced 400 structured questionnaires to collect data on these factors in Ca Mau, and found that there is a significant influence on tourist perception in rural tourism sector, which 58% changing in tourist perception is explained by the independent variables. The regression equation is set as: Y = 1.423 + 0.343X1 – 0.082X2 + 0.273X3 + 0.189X4 (Y= Tourist Perception; X1= Local Culture; X2= Services & Entertainment; X3= Infrastructure; X4= Marketing communication)

This study aimed to identify potential genetic diversity among African swine fever virus (ASFV) strains circulating in central and southern Vietnam. Thirty ASFV strains were collected from domestic pigs and convalescent pigs with ASFV-infected clinical signs from 19 different provinces of central and southern Vietnam during 2019–2021. A portion of the B646L (p72) gene and the entire E183L (p54), CP204L (p30), and B602L (CVR) genes were amplified, purified, and sequenced. Web-based BLAST and MEGA-X software were used for sequence analysis. Analysis of the partial B646L (p72) gene, the full-length E183L (p54) and CP204L (p30) genes, and the central hypervariable region (CVR) of the B602L gene sequence showed that all 30 ASFV isolates belonged to genotype II and were 100% identical to the previously identified strains in Vietnam and China. Analysis of the p72, p54, and p30 regions did not indicate any change in the nucleotide and amino acid sequences among these strains in 3 years of research. No novel variant was found in the CVR within the B602L gene. Analysis of the CVR showed that these ASFV strains belong to subgroup XXXII. The results of this study revealed that these ASFVs shared high homology with ASFV isolates detected previously in northern Vietnam and China. Taken together, the results of this study and a previous study in Vietnam showed high stability and no genetic diversity in the ASFV genome.