Protection of white leg shrimp (Litopenaeus vannamei) against white spot disease virus using oral recombinant bioencapsulated VP28

Aquaculture, is perceived as having the greatest potential to meet the growing demand for aquatic food. Crustaceans form one of the main value added components in aquaculture and among them, shrimp aquaculture is the predominant one. Industrial shrimp fanning, in combination with poor management in shrimp aquaculture, has quickly led to severe pollution in shrimp ponds, thereby creating a suitable environment for development of bacterial and virus diseases. White spot disease is one of the most deadly diseases that are caused heavy loss in all Penaeid shrimps family. In Iran during 2002 to 2004 in the Kuzestan province and in 2005 in Bushehr province, the most ponds and farms infected with white spot and the entire industry was facing threat of closure. Owing to the impact of WSSV infection to shrimp aquaculture, there is an urgent need to develop suitable strategies to protect cultured shrimps and make aquaculture more sustainable. Therefore, this study aimed to examine the possibility of protecting shrimp against white spot syndrome virus using bioencapsulated Anemia with E. coil containing the recombinant protein VP28, designed. Virus genome was extracted from naturally infected Litopenaeus vannamei in the Choebdch farms and VP28 gene by designed primers was amplified, extracted, purified and cloned in E. coli TGI. Protein expression evaluated and inactivated bacteria containing recombinant protein encapsulated in Artemia nauplii. White shrimp post larvae stage 5 were fed for 5 days with recombinant nauplii and twice on days 7 and 25 after feeding with Artemia nauplii were challenged with white spot virus. The results of the first experiment revealed that cumulative mortality percent in the group receiving the bacteria containing recombinant plasmid (pMal + VP28) was %14.44±1.11 and the relative percent survival %80.30±1.51. In this group the mortality rates in the various repetitions varied from the 13.33% to 16.66% and relative percent survival of 77.27% to 81.81%. in the Non-recombinant plasmid group (pMal) Mean percent mortality was% 33.33±3.84 and the Relative Percent Survival %54.54±5.24 and in the group that received bacteria contained no recombinant plasmid the Mean cumulative mortality percent was%48.88 ± 5.87 and Relative Percent Survival%33.33± 8.01.

Detection of viral diseases in shrimp Litopenaeus vannamei in Iran with emphasis on white spot disease prevention by using marine alga extract

Nowadays, following was expanded shrimp breeding and culture; viral diseases have been main problem which threatened shrimp industry in the country. Therefore, shrimp samples were obtained from different stages of Litopenaeus vannmei life cycle (larval, post larval, juveniles, adults and broodstocks) based on clinical signs in the breeding center and shrimp farming from Bushehr, Khozestan and Sistan and Baluchestan provinces. Viral diseases were detected by PCR (Polymerase Chain Reaction), histopathology and transmission electron microscopy (TEM) methods. Results of the PCR were indicated present white spot virus (WSV) in juveniles, sub adults and adults shrimp with medium intensity from three provinces, but it was not showed in larval and post larval stages. Histopathological sections were indicated hypertrophy and basophilic Cowdry type A formation in nucleus cells of gill, haematopoietic, lymphoid and epithelial's cuticles and intestinal tissues which was associated with small vacuoles increased in B cells of hepatopancreas tissue of infection shrimps. Transmission electronic microscopic studies were demonstrated that the length and diameter virus was detected, respectively, 300 ± 20 nm and 75 ± 5 nm. Considerable, results of the PCR were only displayed IHHNV in juvenile, adult and broodstock shrimps from breeding and farming center of Bushehr province. The main lesion pathology was formed eosinophilic Cowdry type A in nucleus cells of gill, haematopoietic, lymphoid and epithelial's cuticles and intestinal tissues. Whereas penaeid shrimps are lack specific immune system, hence, in the present study was used of marine alga (Lurensia snideria) collected from along costal Persian Gulf of Bushehr province for viral diseases were prevented. Powder alga extract were added with a ratio of 1 % to shrimp diet. Total haemocyte count (THC) and total protein plasma (TPP) were increased after 5 days of oral administration diets. When shrimps were infected by with spot virus experimentally, THC and TPP gradually were increased in both two groups (shrimps fed with diet containing alga extract and without alga extract) after 48h. Nevertheless; THC, TPP and survival of shrimp fed with diet containing alga extract were more than shrimp control in 15 days. So, oral administration Lurensia snideria extract was capable prevention infected L. vannamei via stimulant specific immune system.