Avian IRF1 and IRF7 Play Overlapping and Distinct Roles in Regulating IFN-Dependent and -Independent Antiviral Responses to Duck Tembusu Virus Infection

Avian interferon regulatory factors 1 and 7 (IRF1 and IRF7) play important roles in the host’s innate immunity against viral infection. Our previous study revealed that duck tembusu virus (DTMUV) infection of chicken fibroblasts (DF1) and duck embryo fibroblasts (DEFs) induced the expression of a variety of IFN-stimulated genes (ISGs), including VIPERIN, IFIT5, CMPK2, IRF1, and IRF7. IRF1 was further shown to play a significant role in regulating the up-expression of VIPERIN, IFIT5, and CMPK2 and inhibiting DTMUV replication. In this study, we confirm, through overexpression and knockout approaches, that both IRF1 and IRF7 inhibit DTMUV replication, mainly via regulation of type I IFN expression, as well as the induction of IRF1, VIPERIN, IFIT5, CMPK2, and MX1. In addition, IRF1 directly promoted the expression of VIPERIN and CMPK2 in an IFN-independent manner when IRF7 and type I IFN signaling were undermined. We also found that non-structural protein 2B (NS2B) of DTMUV was able to inhibit the induction of IFN-β mRNA triggered by Newcastle disease virus (NDV) infection or poly(I:C) treatment, revealing a strategy employed by DTMUV to evade host’s immunosurveillance. This study demonstrates that avian IRF7 and IRF1 play distinct roles in the regulation of type I IFN response during DTMUV infection.     

苯丙氨酸二肽类化合物073对鸭乙型肝炎病毒DNA的抑制作用

目的观察苯丙氨酸二肽类化合物073对雏鸭乙型肝炎病毒DHBV-DNA的抑制效果。方法90只感染DHBV的北京雏鸭,随机分为5组:对照组,苯丙氨酸二肽类化合物073低、中、高剂量组(0.025g·kg-1、0.05g·kg-1和0.1g·kg-1)和拉米夫定组(0.05g·kg-1)。于给药前、给药d7、d14及停药后d3,各组雏鸭腿静脉取血,分离血清,样品点膜,标记DHBV-DNA探针,血清斑点杂交,放射自显影膜片斑点检测。以杂交斑点吸光度值进行自身和组间比较,并作鸭肝组织病理检查评价。结果苯丙氨酸二肽类化合物073低、中、高剂量组能明显降低鸭血清DHBV-DNA水平,给药d7、d14及停药后d3的抑制率与对照组比较,均有非常显著差异(P<0.01)。肝组织病理检查发现对照组鸭肝细胞的变性坏死较重,而苯丙氨酸二肽类化合物073中、高剂量组则较轻。结论苯丙氨酸二肽类化合物073对DHBV-DNA有明显的抑制作用,而且有保护肝细胞的作用。     

六月青皂苷抗鸭乙型肝炎病毒及保护肝细胞的研究

目的:观察六月青皂苷(the saponins of Liuyueqing,TLYQ)抗鸭乙型肝炎病毒(duck hepatitis Bvirus,DHBV)与保护肝细胞的作用。方法:将DHBV-DNA阳性麻鸭随机分为TLYQ高、中、低剂量治疗组、拉米夫定组和模型组,分别给予相应药物进行干预。用药前、后7 d,14 d及停药后7 d,取静脉血,检测DH-BV-DNA拷贝量和ALT/AST变化情况。结果:TLYQ大剂量组给药后d 7,d 14即能明显抑制DHBV-DNA,停药后仍有一定的抑制作用。中、低剂量组与模型组比较,有一定的病毒抑制作用。在用药后d 14,停药后d 7,ALT/AST较模型组明显下降,有显著性差异。结论:TLYQ具有有效抑制DHBV-DNA和保护肝细胞的作用。     

Genetic characterization of duck Tembusu virus in Thailand, 2015‐2017: Identification of a novel cluster

Duck Tembusu virus (DTMUV) infected cases have increasingly been observed in several duck farms in Thailand since its first report in 2013. However, information on the genetic characteristic of DTMUVs recently circulating in ducks in Thailand is limited. In this study, we investigated the geographic distribution and genetic characteristic of DTMUVs recently circulating in ducks in Thailand during 2015–2017. Of the 288 clinical samples obtained from 89 ducks farms located in duck raising areas of Thailand, 65 samples (22.57%) of 34 duck farms (38.20%) were DTMUV positive. Our results demonstrated that DTMUV was extensively distributed in duck raising areas of Thailand. Phylogenetic analysis of the E and NS5 genes revealed that DTMUVs circulating in Thailand were divided into three distinct clusters, including cluster 1, subcluster 2.1 and a novel cluster 3. Among these three clusters, subcluster 2.1 was a predominant cluster of DTMUV circulating in duck populations in Thailand during 2015–2017. It is interesting to note that a novel cluster of DTMUV (cluster 3), which was genetically different from any of the previously reported DTMUV clusters, was first identified in this study. In conclusion, our data demonstrated the circulation of different clusters of DTMUV and the presence of a novel DTMUV cluster in ducks in Thailand. This study highlights the high genetic diversity of DTMUVs in Thailand and the necessity of the routine surveillance of DTMUV for early detection, prevention and control of newly emerging DTMUVs.     

Development of an in-house ELISA for detection of antibodies against Enterococcus cecorum in Pekin ducks

ABSTRACT

Enterococcus cecorum (EC) is known to cause skeletal lesions in broiler chickens and also systemic infections in Pekin ducks. Despite the importance of the pathogen, there is still a lack of serological diagnostic tools for the detection of EC infections. Here we describe the development of an in-house indirect enzyme-linked immunosorbent assay (ELISA) for the detection of EC-specific antibodies and its application by examination of 67 sera from experimentally infected Pekin ducks, 710 field samples from four Pekin duck breeder flocks previously vaccinated with inactivated vaccines, and 80 samples from commercial Pekin ducks coming from vaccinated parent flocks. All groups that had been experimentally inoculated via the air sac route were positive in the new ELISA, with significantly (P?≤?0.05) increased mean sample/positive (S/P) ratios of 0.71–2.70 at days 7, 14 and 21 post-infection, while orally inoculated ducks and the EC-free control group remained negative with mean S/P ratios of 0.0–0.15. Antibodies were also detected in each of four vaccinated Pekin duck breeder flocks; 67.8% of the samples were antibody positive. The highest S/P ratios were found between 16 and 26 weeks (median S/P ratios from 0.15 to 1.03), but antibodies were still detected in some serum samples in weeks 61–67 post-hatch. No antibodies were detected in the commercial Pekin ducks. Antibody development in the ducks may be influenced by the composition of the inactivated vaccine. The new ELISA provides a useful tool for investigations of response to EC infections and vaccinations.     

Retrospective investigation and molecular characteristics of the recombinant Muscovy duck parvovirus circulating in Muscovy duck flocks in China

The recombinant Muscovy duck parvovirus (rMDPV) has been recently characterized and identified in China. However, whether other additional rMDPV field isolates exist, and whether these strains possess common molecular characteristics, remain to be explored. In this retrospective study, two new rMDPV isolates, namely, JH06 and JH10, were identified through genome sequencing and recombination analysis. JH06, JH10, and four previously characterized rMDPV strains (SAAS-SHNH, ZW, FJM3, and PT97) underwent the same recombination events in a 1.1-kb region in their VP3 genes and displayed highly consistent beginning and ending breakpoints. JH06, JH10, SAAS-SHNH, ZW, and FJM3, but not PT97, underwent recombination in their P9 promoter regions. In both recombination events, the classical MDPV strain YY acted as the major parent, whereas the virulent strain DY16 and the vaccine strain SYG61v of goose parvovirus (GPV) served as the minor parents. The sequence alignments of inverted terminal repeats (ITRs) revealed that rMDPV strains shared higher identities (96.0%–97.2%) with classical MDPV strains than with GPV and contained typical one-nucleotide-pair deletions in the palindromic stems of their ITRs. This work elucidated the common molecular characteristics and differences of six rMDPV strains. The results of this work will facilitate the preparation of an efficacious vaccine for the protection of Muscovy ducks against rMDPV infection.     

Use of muscovy duck embryo fibroblasts for the isolation of viruses from wild birds

Summary Techniques are described for the preparation, cryopreservation, and inoculation of Muscovy duck embryo cell cultures. The procedure yields a susceptible reproducible cell culture system for the isolation and cultivation of viruses from wild birds.     

金定鸭肠粘膜碱性磷酸单酯酶氨基酸组成的初步分析

以金定鸭肠粘膜为材料，用正丁醇抽提，丙酮沉淀，分离出粗酶，经弱碱型阴离子纤维素ＤＥＡＥ－３２和Ｓｅｐｈａｄｅｘ Ｇ－２００柱层析，得到纯化倍数为１３８倍的碱性磷酸单酯酶。ＳＤＳ－ＰＡＧＥ检测酶液纯度，氨基酸自动分析仪测定其氨基酸组成，比较不同来源的碱性磷酸单酯酶氨基酸的组成。