Vaccination of Plasmid DNA Encoding Somatostatin Gene Fused with GP5 Gene of Porcine Reproductive and Respiratory Syndrome Virus Induces Anti-GP5 Antibodies and Promotes Growth Performance in Immunized Pigs

Comparative transcriptome profiling of low light tolerant and sensitive rice varieties induced by low light stress at active tillering stage

Low light intensity is a great limitation for grain yield and quality in rice. However, yield is not significantly reduced in low light tolerant rice varieties. The work therefore planned for comparative transcriptome profiling under low light stress to decipher the genes involved and molecular mechanism of low light tolerance in rice. At active tillering stage, 50% low light exposure for 1 day, 3 days and 5 days were given to Swarnaprabha (low light tolerant) and IR8 (low light sensitive) rice varieties. Illumina (HiSeq) platform was used for transcriptome sequencing. A total of 6,652 and 12,042 genes were differentially expressed due to low light intensity in Swarnaprabha and IR8, respectively as compared to control. CAB, LRP, SBPase, MT15, TF PCL1 and Photosystem I & II complex related gene expressions were mostly increased in Swarnaprabha upon longer duration of low light exposure which was not found in IR8 as compared to control. Their expressions were validated by qRT-PCR. Overall study suggested that the maintenance of grain yield in the tolerant variety under low light might be results of accelerated expression of the genes which enable the plant to keep the photosynthetic processes moving at the same pace even under low light.

Efficacy and safety of an oral somatostatin DNA vaccine without antibiotic resistance gene in promoting growth of piglets

This study aimed to evaluate the efficacy and safety of an oral DNA vaccine against somatostatin (SS) (pGS/2SS-asd, encoding two copies of somatostatin genes) mediated by attenuated Salmonella choleraesuis C500 without antibiotic resistance gene on piglets growth. A total of 50 piglets were uniformly divided into five groups. The animals in the first three groups were orally given vaccine in dose of either 5 9 1010, 5 9 109 or 5 9 108 colony-forming units (CFU).The remaining two groups were orally administered with either bacteria C500(containing pVAX-asd plasmid without somatostatin gene) or phosphate buffered saline (PBS) as controls. The results indicated that the vaccine induced SS-specific antibodies in a dose-dependent pattern. Compared with the PBS control, animals in the high-dose group showed lower SS levels and higher growth hormone (GH) levels in sera. Average daily gain of animals in the high dose group was increased by 32.88% and 26.46% during 4 and 8 weeks,respectively. Anti-SS antibodies were positively correlated with either GH levels or average daily gain at week 8 after primary immunization (P < 0.05). Faecal,soil and water samples originating from immunized piglets and surrounding environment were collected. The target gene (the fusion gene GS/2SS) of C500(pGS/2SS-asd) was not detected by PCR amplification in these samples,indicating that the surrounding environment was not contaminated by residual recombinant bacteria. In conclusion, the vaccine without antibiotic resistance gene is attributable to improve growth performance of piglets through an influence on GH secretion. Moreover, the immunization did not contaminate the surrounding environment of animals.

Immune responses in pigs induced by recombinant DNA vaccine co-expressing swine IL-18 and membrane protein of porcine reproductive and respiratory syndrome virus

In this study, two DNA vaccines, which express the membrane (M) protein of porcine respiratory and reproductive syndrome virus (PRRSV) (pEGFP-M) and co-express both M and swine IL-18 (pEGFP-IL18-M), were constructed and their abilities to induce humoral and cellular responses in piglets were comparatively evaluated. Experimental results showed that both recombinant DNA vaccines could not elicit neutralizing antibodies in the immunized piglets. However, both DNA vaccines elicited Th1-biased cellular immune responses. Notably, pigs immunized with the plasmid pEGFP-IL18-M developed significantly higher levels of IFN-γ and IL-2 production response and stronger specific T-lymphocyte proliferation response than the pigs inoculated with the plasmids pEGFP-M and pEGFP-IL18 (P < 0.05). These results illustrated that co-expression of M and IL-18 proteins could significantly improve the potency of DNA vaccination on the activation of vaccine-induced virus-specific cell-mediated immune responses in pigs, which may be used as a strategy to develop a new generation of vaccines against highly pathogenic PRRSV.

Oral and intranasal administration of somatostatin DNA vaccine mediated by attenuated Salmonella enterica serovar Typhimurium to promote growth of piglets

An attenuated strain of Salmonella typhimurium has been used as a carrier for oral and intranasal genetic immunization. Here, we evaluate the efficacy of a vaccine strain of S. typhimurium. CSO22 (pGM-CSF/SS, plasmid granulocyte-macrophage colony-stimulating factor/somatostatin) expressing two copies of SS genes. A total of 115 piglets, aged 2 months old, were either orally or intranasally immunized against the vaccine strain CSO22 (pGM-CSF/SS) with three dosages (5 × 10(10) colony forming units (CFU), 5 × 10(9) CFU and 5 × 10(8) CFU). For oral immunization, the specific anti-SS antibodies were detected in the immunized piglets. The levels of SS antibodies in the high-dose immunized group (5 × 10(10) CFU) were significantly higher than that in the phosphate buffered saline immunized group (P < 0.01) and 40% of animals were positive in SS antibodies in the high-dose immunized group. Moreover, the weight gain of the high-dose group was increased by 20.86%, 10.26% and 15.30% during 4, 8 and 12 weeks, respectively, after immunization in comparison to the control. For intranasal immunization, the growth of the low-dose group was increased by 10.23% in the whole test period (12 weeks). In conclusion, our results suggest that the recombinant strain could elicit anti-SS antibodies and improve the growth performance of immunized piglets, and that the oral immunization program is better than the intranasal program.

Construction of a fusion protein expression vector pGS/2SS-M4GFP without antibiotic resistance gene and its subcellular localization in different cell lines

A novel plasmid pGS/2SS-M4GFP was constructed in the present study by recombination of GS/2SS gene and enhanced green fluorescent protein (M4GFP) sequence. The GS/2SS fusion gene encoding two copies of somatostatin genes was firstly introduced into pVAX-asd vector in which the kanamycin resistance cassette was replaced by the asd cassette. The M4GFP gene was then fused into 3' end of GS/2SS gene in the proper reading frame. After purified, plasmid pGS/2SS-M4GFP was transfected into different cell lines derived from pig kidney and human cancer cells. The transcription process of GS/2SS gene was confirmed by RT-PCR, and the localization as well as expression of GS/2SS-M4GFP fusion protein was observed by confocal microscopy and ELISA. Transfection results revealed that sole M4GFP was localized within the cytosol and the nucleus, while fusion protein GS/2SS-M4GFP was localized only in the cytoplasm. Furthermore, it should be noted that subcellular localization of GS/2SS-M4GFP was not specific to one cell line, but appeared to be common across a variety of cell lines. These results provide for the first time valuable evidence that M4GFP is a versatile tool to trace GS/2SS protein and pave the way for further study on its tissue distribution and immunological mechanism in vivo.