RESUMO
Although alginate is known as an immunostimulant in shrimp, the comprehensive and simultaneous study on its activity to resolve the relationship of the hematological parameters, upregulation of immune-related gene expression, and resistance to pathogen has not been found in shrimp. We performed experiments to evaluate the effect and mechanism of alginate from S. siliquosum on Pacific white shrimp immune system. Hematological parameters were examined after oral administration of Na alginate in the shrimp. White spot syndrome virus (WSSV) was injected to the shrimp at 14 days, and its copy number was examined quantitatively (qRT-PCR). Immune-related gene expression was evaluated by qRT-PCR. Alginate increased some hematological immune parameters of shrimp. Before WSSV infection, expression levels of Toll and lectin genes were upregulated. The lectin gene were upregulated post infection, and the Toll gene in all the treatments were downregulated, except the shrimps fed with alginate at 6.0 g kg-1 at 48 h post infection (hpi). The shrimps fed with alginate at 6.0 g kg-1 were the most resistant and gave the least WSSV copy number at 48 hpi. Resistance of shrimps fed the alginate-supplemented diets against WSSV was significantly higher compared to that of the control treatment with 56% and 10% of survival rates, respectively. Oral administration of alginate did not affect the growth and total protein plasma. At 120 h post challenge, alginate treatment at 6.0 g kg-1 exhibited the highest survival rate. It is concluded that oral administration of alginate enhanced the innate immunity by upregulating immune-related gene expression. Consequently, the enhancement of the shrimp innate immunity improves the resistance against WSSV infection.
Assuntos
Alginatos/administração & dosagem , Resistência à Doença/efeitos dos fármacos , Imunidade Inata/efeitos dos fármacos , Penaeidae/efeitos dos fármacos , Sargassum/química , Vírus da Síndrome da Mancha Branca 1/efeitos dos fármacos , Administração Oral , Alginatos/isolamento & purificação , Animais , Proteínas de Artrópodes/genética , Proteínas de Artrópodes/imunologia , Resistência à Doença/genética , Dosagem de Genes , Regulação da Expressão Gênica , Genes Virais/efeitos dos fármacos , Interações Hospedeiro-Patógeno/genética , Interações Hospedeiro-Patógeno/imunologia , Lectinas/genética , Lectinas/imunologia , Penaeidae/genética , Penaeidae/imunologia , Penaeidae/virologia , Transdução de Sinais , Receptores Toll-Like/genética , Receptores Toll-Like/imunologia , Vírus da Síndrome da Mancha Branca 1/genética , Vírus da Síndrome da Mancha Branca 1/metabolismoRESUMO
The Total Haemocyte Count (THC), phenoloxidase (PO), Superoxide Dismutase (SOD) activity, Phagocytic Activity/Index and Total Protein Plasma (TPP) were examined after feeding the white shrimp Litopenaeus vannamei with diets supplemented with three different types of alginates (acid, calcium and sodium alginates). Immune-related genes expression was evaluated by quantitative Real Time PCR (qRT-PCR). Results indicated that the immune parameters directly increased according to the doses of alginates and time. The 2.0 g kg(-1) of acid and sodium alginate treatments were gave better results. Four immune-related genes expression i.e. LGBP, Toll, Lectin, proPO were up regulated. It is therefore concluded that the supplementation of alginate of Sargassum siliquosum on the diet of L. vannamei enhanced the innate immunity as well as the expression of immune-related genes. It is the first report on the simultaneous evaluation of three alginate types to enhance innate immune parameters and immune-related genes expression in L. vannamei.