Effect Of Resveratrol On Pseudorabies Virus-Induced Reproductive Failure

Pseudorabies virus (PrV) can infect a variety of animals in livestock production, and pig is the most susceptible animal. In sow, it can cause serious reproductive disorders resulting in huge economic losses. At present, vaccinnation or use of drugs are the common methods for the prevention and treatment of pseudorabies. Due to the limitation with stress, risks and resistance to drugs, lookng for feed additives with safety, no stress and high effeciency is of great significance. Resveratrol is a natural plant extract, studies have shown that it is involved in anti-oxidation, anti-inflammation, anti-virus and so on, which can effectively enhance the body’s resistance against diseases. Whether it has preventive effect against pseudorabies virus has not been reported.In this study, firstly, the effect of resveratrol on PrV infection in vitro were investgated through three different treatments; then, the effect of resveratrol on mouse reproductive failure was further studied in vivo by establishing a mouse reproductive failure model induced by PrV. The results are shown as following:1. In vitro experiments:relative cell viability and the amount of nucleic acid of the viral VP2 gene were detected using MTS assay and real time PCR after treatment. ①Treated cells with Resveratrol or infected cells with PrV to study their individual effect on cells:pre-treatment with 50 μM of resveratrol can improve cell viability within 24 h; PrV infection can affect cell viability as well an increasing amount of its VP2 nucleic acid with a time-dependent manner. ②Effects of resveratrol on PrV infection using three different treatments:i. cells were pretreated with resveratrol followed by PrV infection to study the preventive effect of resveratrol on PrV. Results showed that resveratrol could improve the viablity of the cells infected with PrV within a certain period of time.50 μM of RES inhibited the level of viral nucleic acid within 24 h, but promoted the proliferation of the virus with the time development, ii. Cells were infetecd with PrV followed by treatment of resveratrol to study the therapeutic effect of resveratrol on PrV infection. Results showed that treatment with 50 μM resveratrol could increase cells’relative viability within 36 h when compared to the PrV infected group, iii. Pre-mixed the resveratrol with PrV followed by cells’ infection to study whether there is a direct inactivative effect of resveratrol on PrV. Results showed that:whithin 36 h, cells relative relatively higher than the viral infected group when using 50 μM resveratrol.2. In vivo animal experiments:in this study, pre-treated mice with three different doses of resveratrol for two weeks, then established pregnancy followed by infection wih PrV to induce reproductive failure. The results show that:in PrV infection could induce mouse reproductive failure resulting in obvious severe maternal performance including miscarriage, stillbirth, low litter size and so on. Viral pathogen was further detected in the animal model:Ⅰ. weak signal of viral VP2 gene could be detected obly in brain tissues of the PrV infeted mice using PCR; Ⅱ. No signal was detected in other tissues as well cells infected with all tissue homogenates. Pretreated mice with different doses of resveratrol could prevent reproductive disorders caused by the PrV and the dose of 50 mg/kg/d showed a better preventive effect. Pretreatment with resveratrol could delay the survival time against the PrV attack and improve the daily gain of the neonates delivered by the PrV-infected mother mice. Levels of seral progesterone showed an increase trend when pretreated with resveratrol, but no significant difference was obtained.Based on the above mentioned results:resveratrol showed a certain effect against PrV in vitro; infection of PrV could cause reproductive disorders in mice and resveratrol showed a preventive effect on mice reproductive failure induced by PrV. These results can provide a theoretical basis for resveratrol developed as a function of feed additive products in animal production.