Eukaryotic expression of GP5 and M protein of porcine reproductive and respiratory syndrome virus and immunogenicity evaluation / 生物工程学报

In order to understand the prevalence and evolution of porcine reproductive and respiratory syndrome virus (PRRSV) in China and to develop subunit vaccine against the epidemic lineage, the genetic evolution analysis of PRRSV strains isolated in China from 2001 to 2021 was performed. The representative strains of the dominant epidemic lineage were selected to optimize the membrane protein GP5 and M nucleotide sequences, which were used, with the interferon and the Fc region of immunoglobulin, to construct the eukaryotic expression plasmids pCDNA3.4-IFNα-GP5-Fc and pCDNA3.4-IFNα-M-Fc. Subsequently, the recombinant proteins IFNα-GP5-Fc and IFNα-M-Fc were expressed by HEK293T eukaryotic expression system. The two recombinant proteins were mixed with ISA206VG adjuvant to immunize weaned piglets. The humoral immunity level was evaluated by ELISA and neutralization test, and the cellular immunity level was detected by ELISPOT test. The results showed that the NADC30-like lineage was the main epidemic lineage in China in recent years, and the combination of IFNα-GP5-Fc and IFNα-M-Fc could induce high levels of antibody and cellular immunity in piglets. This study may facilitate the preparation of a safer and more effective new PRRSV subunit vaccine.

Positive effects of porcine IL-2 and IL-4 on virus-specific immune responses induced by the porcine reproductive and respiratory syndrome virus (PRRSV) ORF5 DNA vaccine in swine

The purpose of this study was to investigate the effects of porcine interleukin (IL)-2 and IL-4 genes on enhancing the immunogenicity of a porcine reproductive and respiratory syndrome virus ORF5 DNA vaccine in piglets. Eukaryotic expression plasmids pcDNA-ORF5, pcDNA-IL-2, and pcDNA-IL-4 were constructed and then expressed in Marc-145 cells. The effects of these genes were detected using an indirect immunofluorescent assay and reverse transcription polymerase chain reaction (RT-PCR). Characteristic fluorescence was observed at different times after pcDNA-ORF5 was expressed in the Marc-145 cells, and PCR products corresponding to ORF5, IL-2, and IL-4 genes were detected at 48 h. Based on these data, healthy piglets were injected intramuscularly with different combinations of the purified plasmids: pcDNA-ORF5 alone, pcDNA-ORF5 + pcDNA-IL-2, pcDNA-ORF5 + pcDNA-IL-4, and pcDNA-ORF5 + pcDNAIL-4 + pcDNA-IL-2. The ensuing humoral immune responses, percentages of CD4+ and CD8+ T lymphocytes, proliferation indices, and interferon-gamma expression were analyzed. Results revealed that the piglets co-immunized with pcDNA-ORF5 + pcDNA-IL-4 + pcDNA-IL-2 plasmids developed significantly higher antibody titers and neutralizing antibody levels, had significantly increased levels of specific T lymphocyte proliferation, elevated percentages of CD4+ and CD8+ T lymphocytes, and significantly higher IFN-gamma production than the other inoculated pigs (p < 0.05).

Síndrome reprodutiva e respiratória dos suínos: uma breve revisäo / Porcine reproductive and respiratory syndrome: a brief review

A síndrome reprodutiva e respiratória dos suínos (Porcine Reproductive and Respiratory Syndrome - PRRS) é uma doença relativamente nova dos suínos que foi detectada primeiramente em 1985 nos Estados Unidos, e em 1990 no continente Europeu. A síndrome é causada pelo PRRS vírus (PRRSV), o qual foi incluído em uma nova família de vírus, a Arteriviridae. A infecçäo pelo PRRSV causa problemas reprodutivos em fêmeas gestantes, o quais säo caracterizados por abortos no final da gestaçäo e/ou parto precoce, onde pode-se observar um elevado número de fetos mumificados e natimortos; leitöes que nascem infectados säo fracos e economicamente inviáveis. Os problemas respiratórios causados pela infecçäo pelo PRRSV podem se manifestar em suínos de todas as faixas etárias, e säo semelhantes a influenza. Embora PRRS tem sido detectada na maioria dos países em que a suinocultura tem importância econômica significativa, näo há informaçöes publicadas a respeito da doença ou do vírus no Brasil. No entanto, devido as perdas econômicas significativas que essa síndrome causou nos países já afetados, e da possibilidade do vírus ser eventualmente introduzido nos rebanhos brasileiros, é necessário reconhecer a doença imediatamente, e tomar as devidas medidas para o diagnóstico e controle em casos de surtos de problemas reprodutivos e respiratórios.