Effects of Feed Mixed with Lactic Acid Bacteria and Carbon, Nitrogen, Phosphorus Supplied to the Water on the Growth and Survival Rate of White Leg Shrimp (Penaeus vannamei) Infected with Acute Hepatopancreatic Necrosis Disease Caused by Vibrio parahaemolyticus.

This study aimed to evaluate the growth, survival rate, and resistance to acute hepatopancreatic necrosis disease (AHPND) of white leg shrimp (Penaeus vannamei) by using Lactobacillus plantarum, Lactobacillus fermentum, and Pediococcus pentosaceus mixed with feed, and at the same time supplying CNP in a ratio of 15:1:0.1 to the water. As a result, the treatments that shrimp were fed with feed containing lactic acid bacteria (LAB), especially L. plantarum, have increased shrimp growth, total hemocyte cells, granulocyte cells, and hyaline cells significantly (p < 0.05) in comparison to the control group. The supply of CNP to the water has promoted the intensity of V. parahaemolyticus effects on shrimp health and significantly decreased total hemocyte cells, granulocyte cells, and hyaline cells by 30-50% in the period after three days of the challenge, except in L. plantarum treatment, which had only a 20% decrease compared to other treatments. In CNP supplying treatments, the AHPND infected rate and mortality of shrimp were higher than those in other treatments. In summary, the supply of CNP had significantly reduced the shrimp's immune response and promoted the susceptibility of shrimp to AHPND in both cases of use with and without LAB-containing diets.

The influence of a GT repeat polymorphism on poly(I:C) induction of the grouper MxII gene promoter in GK cells.

Interferons play an important role in the fish innate immune system against viral infection by inducing the interferon stimulated genes, such as Mx gene. We cloned the MxII gene promoter from orange-spotted grouper and found three MxII gene promoters. All of them contained two interferon stimulated response elements (ISREs), and three dinucleotide repeat sequences located at 5' end of ISREs. Interestingly, there is a polymorphic GT repeat element located upstream of these ISREs. The three MxII gene promoters respectively contained 27, 29, and 31 GT repeats, namely EcMx_27, EcMx_29, and EcMx_31. To determine whether GT repeat element influence the MxII gene expression, the MxII gene promoters were subcloned into promoterless reporter plasmid and transfected into grouper kidney (GK) cells. The results showed that a significant induction by poly(I:C) was detected in GK cells transfected with pEcMx_31 (2.65 folds) whereas there was no induction in GK cells transfected with pEcMx_27 and pEcMx_29. However, the significant induction by nervous necrosis virus (NNV) infection was found in GK cells separately transfected with three reporter plasmids. These results suggest that the GT repeat element plays an important role in modulation of MxII gene expression and the induction by poly(I:C) and NNV may be mediated through different signal transduction pathways.

Complete Genome Sequence of Nervous Necrosis Virus Isolated from Orange-Spotted Grouper (Epinephelus coioides) in Taiwan.

The genome sequence of nervous necrosis virus strain KS1 isolated from orange-spotted grouper (Epinephelus coioides) was cloned and analyzed. The viral genome is composed of two single-stranded positive-sense RNA molecules, RNA1 and RNA2. Phylogenetic analysis shows that the virus strain KS1 belongs to the red-spotted grouper nervous necrosis virus genotype.