title: Inhibition of highly pathogenic porcine reproductive and respiratory syndrome virus replication by recombinant pseudorabies virus-mediated RNA interference in piglets.
abstract: Highly pathogenic porcine reproductive and respiratory syndrome virus (HP-PRRSV) is a variant of porcine reproductive and respiratory syndrome virus (PRRSV) which, in recent years, has caused heavy economic losses to swine-producing areas. Although current vaccines are somewhat prophylactic, they provide only limited protection. Furthermore, there are currently no effective anti-HP-PRRSV drugs. Consequently, it is necessary to develop novel antiviral strategies. In the present study, three recombinant pseudorabies viruses (PRV) expressing siRNAs against the ORF7 of HP-PRRSV strain HN1 (PRV gG-/siRNAN1, PRV gG-/siRNAN2, and PRV gG-/siRNAN3) were evaluated for the inhibition of HP-PRRSV replication. The results indicated that recombinant PRV-mediated siRNA could significantly decrease the replication of traditional PRRSV strain H1 at mRNA and protein levels in Marc-145 cells. Moreover, one recombinant PRV (PRV gG-/siRNAN2) was found to be inhibit the multiplication of HP-PRRSV strain HN1 effectively in Marc-145 cells at both the protein and ORF7 mRNA level. Twenty 21-day-old healthy weaned piglets were divided into four groups of five piglets each. Groups 1 and 2 were injected i.m. with PRV gG-/siRNAN2 and PRV gG-/siRNANeg individually. The piglets in group 3 were challenged with the HP-PRRSV control. After 24h, the piglets in groups 1-3 were challenged i.m. with HP-PRRSV strain HN1, while those in group 4 were i.m. administered with PBS as a negative control. The results showed that HP-PRRSV in serum and lung samples from piglets was effectively inhibited by PRV gG-/siRNAN2. The clinical signs and gross lesions of piglets inoculated with PRV gG-/siRNAN2 were significantly less invasive than those of the PRV gG-/siRNANeg group and HP-PRRSV control group. These results showed that siRNAs mediated by recombinant PRV could effectively suppress HP-PRRSV replication in vitro as well as in vivo. RNAi mediated by recombinant PRV presents a potential novel method to prevent HP-PRRSV infections in swine. However, the protective efficiency of PRV gG-/siRNAN2 should be assessed in a larger number of piglets in future studies.
authors.affiliation: Department of Veterinary Medicine, Henan University of Animal Husbandry Economy, Mingli Road, Zhengzhou 450046, People's Republic of China. Electronic address: caosuf2000@163.com.
authors.forename: Su-fang
authors.initials: SF
authors.lastname: Cao
authors.affiliation: College of Animal Science, Xinjiang Agriculture University, Nongda East Road 311, Wulumuqi 830052, People's Republic of China.
authors.forename: Qing-yong
authors.initials: QY
authors.lastname: Guo
authors.affiliation: Department of Veterinary Medicine, Henan University of Animal Husbandry Economy, Mingli Road, Zhengzhou 450046, People's Republic of China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
mesh_terms: D000818:Animals; D004261:DNA Replication; D015316:Genetic Therapy / Q000379:methods / Q000662:veterinary*; D011558:Herpesvirus 1, Suid / Q000235:genetics*; D019318:Porcine Reproductive and Respiratory Syndrome / Q000235:genetics / Q000473:pathology / Q000517:prevention & control*; D019316:Porcine respiratory and reproductive syndrome virus / Q000235:genetics / Q000378:metabolism*; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011897:Random Allocation; D013552:Swine; D014779:Virus Replication
chemical_list: D034741:RNA, Small Interfering
keywords: HP-PRRSV; RNAi; Recombination pseudorabies virus; siRNA