The green alga Chlamydomonas reinhardtii is a model organism for studying mechanism of the body in response to changes in environmental conditions, photosynthesis as well as chloroplast biogenesis and can be modified to produce high value proteins. In this study, we present results on the selection of cultural conditions for the growth of cell wall - deficient mutant C. reinhardtii (503 strain- control) and recombinant 503-2 strain expressing VP28 protein of White Spot Syndrome Virus (WSSV) in 250 ml flasks. Suitable conditions for the growth of both control and recombinant strains were TAP medium, temperature of 25 C, pH = 7, light intensity of 2 klux, C source - Trisbase, N source - nitrate and salinity of 50 - 100 mM. In these conditions, maximum cell density of the control and recombinant strains was 3.20 ± 0.08 x 106 and 2.96 ± 0.17 x 106 cells/ mL after 3 and 7 days of cultivation, respectively. The presence of vp28 gene in the recombinant microalgal strain was stably maintained at all levels of culture. The results of this paper will be a scientific basis for culturing the recombinant C. reinhardtii to obtain algal biomass which had high expression of surface VP28 protein of WSSV’s envelope for edible vaccine production vaccine by feeding in order to prevent white spot disease of shrimp.

Syringomycin E (SRE) is a phytotoxin produced by Pseudomonas syringae pv syringae with high potential as a safe and effective therapy for the control of human fungal infections and as a preservative for the food industry. In this study, 27 strains of P. syringae pv syringae were isolated from plums, potatoes, apricots and peaches, of which P. syringae pv syringae 120 (PS120) showed the highest SRE production levels. Furthermore, random mutagenesis induced by ultraviolet (UV) radiation resulted in the generation of a P. syringae pv syringae mutant that produced 30% more SRE than the parental strain PS120. To elucidate molecular mechanism underlying the higher SRE production ability of the mutant strain, syrB1 and syrB2 genes, which are known to be involved in SRE production, were cloned and sequenced. The nucleotide and amino acid sequences analysis showed that UV radiation induced numerous mutations at the AMP binding site on adenylation domain of syrB1, while no mutation was detected in syrB2 gene. Real-time polymerase chain reaction (PCR) results showed that expression of syrB1 gene in mutant strain was six-fold higher than that of PS120 strain. Taken together, these results suggest that the mutations at AMP binding site and overexpression of syrB1 were responsible for increased biosynthesis of SRE in P. syringae pv syringae.

Meningococcal bacterium Neisseria meningitidis is one of the major causes of meningitis worldwide. Currently in Vietnam, N. meningitidis B and C are the most prevalent invasive serogroups. N. meningitidis expresses two major transmembrane proteins, PorA and PorB, of which PorA showed high levels of polymorphism among strains and has been studied as one component of vaccines against N. meningitidis B. Polymorphisms in porA gene clustered into three variable regions VR1, VR2 and VR3. In this study, we sequenced the entired porA gene of 19 N. meningitidis strains isolated from military units in northern Vietnam during the period 2008 – 2017 in order to: (1) evaluate the polymorphism of porA gene at nucleotide level and predict its immuno-reactivity from annotated amino acide sequences; and (2) compare porA variants of Vietnamese strains with known strains worldwide. Our results showed a high level of polymorphisms among Vietnamese strains, with the highest polymorphism found in VR1, followed by VR2 and VR3. Notably, 5/19 strains in this study showed novel variants at VR2 with unknown immunological reactivity. This result suggested potential novel immunological characteristics of meningococcal strains from Vietnam.

White spot syndrome virus (WSSV) is the leading cause of shrimp mortality in farms all over the world. In Vietnam, for the last five to ten years, WSSV has always been among the top causes of diseases and loss in our shrimp aquaculture. VP28 and VP26 are two capsid proteins of WSSV that commonly used as biomarkers for diagnosis and target antigens for vaccine against WSSV. Recombinant VP28 (rVP28) has been studied and expressed in various expression systems including E. coli, yeast and baculovirus. rVP28 expressed in these systems showed effective protection against WSSV in shrimps, though there remains limitation on expression efficiency and safety. Recently, green microalgae Chlamydomonas reinhardtii has been widely used to express pharmaceutical proteins and edible vaccines for aquaculture thanks to its advantages as a safe and efficient host. C. reinhardtii is also used as nutrious natural food for shrimps due to its benefits towards shrimp health and growth. In this study, the codons of vp28 gene was adapted and chemically synthesized, and transformed into the nucleus genome of C. reinhardtii using electroporation. The presence of a codon optimized vp28 gene in C. reinhardtii genome was confirmed by colony PCR and sequencing; and its expression level was examined by RT-PCR. These results proved our success in creating transgenic C. reinhardtiii expressing rVP28 and set the foundation for our future research on edible vaccine against WSSV for shrimp.

The purpose of this study was to translate the Brief Autism Mealtime Behavior Inventory (BAMBI) questionnaire into Vietnamese to develop and validate the evaluation of feeding behavior in patients with Autism Spectrum Disorder (ASD). This cross - sectional research was conducted at 18 centers raising children with ASD in Vietnam from May 2021 to December 2021. After testing by Cronbach’s alpha index, all 18 factors were kept (Cronbach’s alpha > 0.7). Then, these 18 questions were included in exploratory factor analysis (EFA) resulting in 4 questions being eliminated (Loading factor > 0.5). The remaining 14 sentences that were built into a model with 5 factors and CFA confirmatory factor analysis showed that this BAMBI’s model is considered to be quite close to the fit model (CFI < 0.9), and divided them into 5 factors (according to EFA) with KMO = 0.757 and Barlett’s Test = 0.000, which was accepted. Therefore, the brief autism mealtime behavior Inventory may be a valid and accurate measuring instrument to evaluate mealtime and feeding difficulties in people with autism in Vietnam.