A non-haemagglutinating isolate of mink enteritis virus

A virus was isolated from mink showing clinical and pathological signs of mink enteritis. This virus was identified as mink enteritis virus (MEV) from results of serological tests, determination of its density in CsCl (1.415 g cm^?3), and morphology, including size (20 nm in diameter). The isolate was designated MEV-S. In contrast to other known MEV strains, the MEV-S isolate has no haemagglutinating (HA) activity with swine red blood cells (RBCs) at 4°C and pH 6.8.Neither was there any HA at other pH values and temperatures, or when worse, bovine and rhesus monkey RBC's were used.     

水貂肠炎病毒LN-10分离株的分离鉴定

为了解我国水貂肠炎病毒(MEV)的流行情况,本研究采用F81细胞从疑似患有肠炎的水貂粪便样品中分离出一株病毒,经形态学、血清学、动物回归试验和分子生物学鉴定,分离的病毒为MEV,命名为LN-10。对该病毒主要结构蛋白VP2基因进行克隆测序和基因进化分析表明,LN-10分离株VP2基因与GenBank中的其他18株MEV株核苷酸和氨基酸均有较高的同源性,分别为99.3%～100%和99%～100%,其中核苷酸同源性与ZYL-1株为100%,而氨基酸同源性与ZYL-1株和Manzhouli株均为100%。本研究为MEV分子流行病学调查和疫苗的研究奠定了基础。     

Virus enteritis of mink. A scanning electron microscopic investigation

Advanced lesions in the jejunal mucosa in virus enteritis of mink were studied by scanning electron microscopy. The changes were found to be in good accordance with those observed in the light microscope, and included ballooned degeneration of entero-cytes, epithelial desquamation, the occurrence of fibrinous pseudo-membranes, atrophy or total loss of villi; partially atrophied villi were frequently fused. In some areas there were incipient regenerative processes, including proliferation of ballooned cells which covered the luminal surface of the damaged jejunal wall.     

The molecular and serological investigation of Feline immunodeficiency virus and Feline leukemia virus in stray cats of Western Turkey

This study aimed to investigate the Feline immunodeficiency virus (FIV) / Feline leukemia virus (FeLV) infection prevalence among looking healthy stray cats in Western Turkey by serologic and molecular-based tests. A total of 1008 blood samples from the stray cats were used in this study. All samples were tested for FIV antibodies / proviral DNA and FeLV antibodies / antigens / proviral DNA. The genetic characterization and phylogenetic analysis of FeLV and FIV were carried out in this study. These cats also tested for Leishmaniasis and Toxoplasmosis previously. FIV Ab and proviral DNA detected in 25.2 % and 25.5 % of samples, respectively. FeLV Ab, Ag, proviral DNA positivity was in 45.2 %, in 3.3 %, in 69.7 %, respectively. The molecular detection and phylogenetic analysis of the current FeLV pol gene and FIV gag gene performed. The molecular characterization for the pol gene of FeLV (enFeLV and exFeLV) among Turkey's cat population was reported for the first time. The exFeLV pol sequences closer to the FeLV-A genotype, and the enFeLV pol sequences overlapped with other enFeLV. The current FIV gag sequences were clustered within the subtypes A, B, and C. The findings revealed FeLV subtype A and FIV subtype-A, subtype-B, subtype-C circulate among Turkish stray cats. Single and multiple co-infection positivity was found higher compared to previous reports.     

水貂细小病毒MEV-LT18株的分离鉴定及遗传进化分析

为了解河北地区水貂肠炎病毒(mink enteritis virus,MEV)的生物学特性,阐明其基因组与遗传进化等特征,采集疑似感染MEV致死貂的肠道组织,PCR鉴定为MEV阳性后,接种F81细胞进行病毒分离鉴定,通过电镜形态学观察、理化特性试验、血清学及分子生物学等试验方法进行验证。结果表明,成功鉴定并分离出1株MEV,命名为MEV-LT18株;电镜观察病毒粒子形态符合细小病毒形态特征;血凝试验发现该分离株不具有血凝性。对NS基因和VP2基因进行序列比对与遗传进化树分析,与Abashiri株进行氨基酸序列对比,结果显示在NS基因上有3处氨基酸发生非同义替换,分别为aa10(Val→Ile)、aa540(Val→Ala)、aa574(Val→Ile),在VP2基因上共有4处氨基酸发生非同义替换,分别为aa232(Ile→Val)、aa236(Thr→Ser)、aa300(Ala→Val)、aa411(Ala→Glu);系统进化树结果显示MEV-LT18株的NS基因和VP2基因分别与MEV-SDNH株和MEV-HLJ株亲缘关系最近,可能处于两者进化过程的过渡阶段。本研究对该地区水貂细小病毒的进化特征提供了一定的参考价值。     

Comparisons of feline panleukopenia virus, canine parvovirus, raccoon parvovirus, and mink enteritis virus and their pathogenicity for mink and ferrets

Parvoviruses from mink (mink enteritis virus [MEV]), cats (feline panleukopenia virus [FPV]), raccoons (raccoon parvovirus [RPV]), and dogs (canine parvovirus [CPV]) were compared. Restriction enzyme analysis of the viral replicative-form DNA revealed no consistent differences between FPV and RPV isolates, but CPV and MEV isolates could be distinguished readily from other virus types. Feline panleukopenia virus, RPV, and MEV, but not CPV, replicated to high titers in mink. However, on the first passage, disease and microscopic lesions were observed only in mink inoculated with MEV. Feline panleukopenia virus and RPV isolates replicated in ferrets, but disease or microscopic lesions were not observed. Feline panleukopenia virus and RPV isolates could be passaged repeatedly in mink and ferrets. Virulence of FPV and RPV isolates was low compared with that of MEV, and only a single mink inoculated with FPV or with RPV developed clinical disease on the sixth passage of virus.     

Detection of mink enteritis virus in mink feces, using enzyme-linked immunosorbent assay, hemagglutination, and electron microscopy

Twenty-five mink were inoculated with mink enteritis virus (MEV). Fecal specimens were collected daily and were simultaneously evaluated for MEV antigen by use of a direct enzyme-linked immunosorbent assay (ELISA), hemagglutination (HA), and electron microscopy. Results of the evaluations indicated that MEV was shed in the feces on postinoculation days 5 and 6. The virus was not detectable by ELISA or HA after postinoculation day 6, although viruses were found in reduced numbers by use of electron microscopy. The ELISA was specific for MEV, and the sensitivity of the ELISA for MEV was comparable with that of HA.     

水貂肠炎病毒的分离及鉴定

应用细胞培养技术,从2006年山东某貂场送检的水貂病料中分离出1株水貂病毒,经PCR及VP2测序分析证明为水貂肠炎病毒(ZYL-MEV-1);动物感染试验表明是一株强毒株,培养1～20代细胞培养物对猪的红细胞血凝结果表明具有低血凝性,与2009年在大连地区流行的水貂肠炎病毒VP2的基因测序相比较同源率100%,提示此分离株可能为我国目前水貂肠炎病毒的主要流行株。     

水貂肠炎细小病毒分离鉴定

从送检的疑似水貂病毒性肠炎的水貂粪便中分离出一株病毒,经形态学、理化特性、血清学和动物试验鉴定表明,分离的病毒为水貂肠炎细小病毒。     

水貂肠炎病毒VP2基因的原核表达及间接ELISA方法的建立

为了对水貂肠炎病毒(MEV)疫苗免疫后抗体水平的监测和疫苗免疫效力的评价,本研究在分析MEV VP2蛋白抗原性的基础上,设计1对特异性引物克隆VP2蛋白抗原性较好的基因片段,将克隆的基因片段定向插入到pProEXHTb原核表达载体中,构建了VP2基因原核表达重组质粒pProEXHTb-VP2A,并实现在大肠杆菌BL21(DE3)中高效表达,经鉴定表达的重组蛋白以包涵体形式存在,免疫印迹试验表明获得的重组蛋白具有与抗体较好的反应原性.应用His-Bind亲和层析柱纯化重组蛋白VP2A,以纯化后的重组蛋白作为ELISA诊断抗原,并对反应条件进行优化,初步建立了检测MEV抗体的VP2A-ELISA方法.确定了抗原最佳包被浓度为9.65 μg/mL,血清最佳稀释倍数为1:10.判定标准为S/P值≥0.312为阳性,S/P值≤0.243为阴性,介于两者之间为疑似.该抗原不与犬瘟热病毒、阿留申病毒阳性血清反应,具有良好的特异性.采用VP2A-ELISA对180份水貂血清样品进行检测,结果显示VP2A-ELISA与HI试验的符合率达到87.8%,表明建立的间接ELISA方法具有较高的敏感性和特异性,为现地免疫貂群抗体检测和MEV流行病学调查提供了一种简便的血清学诊断方法.     

Comparison of the viral proteins of canine parvovirus-2, mink enteritis virus and feline panleukopenia virus

Canine parvovirus-2 (CPV-2), Mink enteritis virus (MEV) and feline panleukopenia virus (FPV) were produced using identical cell culture and purification techniques. The distributions of the haemagglutinating activity of the three different parvoviruses in a CsCl gradient were similar with haemagglutinating peaks identified at 1.48–1.49, 1.42, 1.36 and 1.30–1.31 g cm^?3. The number and distribution of the viral proteins and the equivalent protein molecular weights are similar for all three viruses in SDS-polyacrylamide gels (10%). Four viral proteins were identified and their molecular weights were determined: protein A (77 500–79 500), protein B (63 000–63 500), protein C (61 500–63 000) and protein D (50 000–55 000). The viral protein D although reported for some other parvoviruses has not previously been demonstrated in CPV-2, MEV or FPV.     

Feline leukemia virus and feline immunodeficiency virus.

Ophthalmic manifestations of FeLV or FIV infection can occur in all ocular tissues and may be manifestations of direct viral effects or secondary to viral-related malignant transformation. Additionally, the manifestations of common feline ophthalmic pathogens may be more severe and poorly responsive to therapy because of the immunosuppressive effects of FeLV or FIV infection. Prompt diagnosis of underlying viral infection in cats with ophthalmic disease is paramount for accurate diagnosis and prognosis and is required for appropriate therapeutic decision making.     

Enzyme immunoassay studies on the serological response of turkeys to hemorrhagic enteritis virus

An enzyme-linked immunosorbent assay (ELISA) was developed for the detection of antibodies in turkey serum to hemorrhagic enteritis virus. The ELISA antigen was extracted from turkey spleens and partially purified with fluorocarbon. Antibodies were demonstrated in serum samples of breeding and meat flocks that had been naturally exposed to infection. These samples were also examined in parallel by agar-gel precipitin (AGP); most of the sera were AGP-positive. ELISA, however, was more sensitive in detecting antibodies in day-old sera that were AGP-negative. The passively acquired antibodies were no longer detected by 4 weeks of age. A brisk but short-lived secondary response was detected by ELISA in the sera of turkeys immunized with beta-propiolactone-inactivated extract of infected spleens.     

Feline leukemia virus infection and diseases.

Feline leukemia virus is a naturally occurring, contagiously transmitted and oncogenic immunosuppressive retrovirus of cats. The effects of FeLV are paradoxical, causing cytoproliferative and cytosuppressive disease (eg, lymphoma and myeloproliferative disorders vs immunodeficiency and myelosuppressive disorders). In the first few weeks after virus exposure, interactions between FeLV and hemolymphatic system cells determine whether the virus or the cat will dominate in the host/virus relationship--persistent viremia and progressive infection or self limiting, regressive infection will develop. The outcome of these early host/virus interactions is revealed in the diagnostic assays for FeLV antigenemia and viremia. The latter, in turn, predict the outcome of FeLV infection in cats. Known host resistance factors include age and immune system functional status. Known virus virulence factors are magnitude of exposure and virus genotype. Molecular analysis of FeLV strains indicated that natural virus isolates exist as mixtures of closely related virus genotypes and that minor genetic variations among FeLV strains can impart major differences in pathogenicity. The genetic coding regions responsible for cell targeting and specific disease inducing capacity (eg, thymic lymphoma, acute immunosuppression, or aplastic anemia) have been mapped to the virus surface glycoprotein and/or long terminal repeat regions for several FeLV strains. Infection by specific FeLV strains leads to either malignant transformation or cytopathic deletion of specific lymphocyte and hemopoietic cell population, changes that prefigure the onset of clinical illness. Another notable feature of the biology of FeLV is that many cats are able to effectively contain and terminate viral replication, an important example of host immunologic control of a retrovirus infection and a process that can be selectively enhanced by vaccination. Thus, FeLV infection serves as a natural model of the multifaceted pathogenesis of retroviruses and as a paradigm for immunoprophylaxis against an immunosuppressive leukemogenic retrovirus.