Evaluation of cytotoxicity and antiviral activity of recombinant human interferon alfa-2a and recombinant human interferon alfa-B/D hybrid against bovine viral diarrhea virus, infectious bovine rhinotracheitis virus, and vesicular stomatitis virus in vitro

OBJECTIVE: To evaluate cytotoxicity and antiviral activity of recombinant human interferon alfa-2a and recombinant human interferon alfa-B/D hybrid against cytopathic and noncytopathic bovine viral diarrhea virus (BVDV), infectious bovine rhinotracheitis virus (IBRV), and vesicular stomatitis virus (VSV) in vitro. SAMPLE POPULATION: Primary bovine testicular cells and Mardin Darby bovine kidney cells. PROCEDURES: To evaluate cytotoxicity, cells were added to serial dilutions of each interferon. To evaluate antiviral activity of each interferon, interferons were serially diluted 1:10, and tissue culture cells were added; virus was then added at 3 time points. Prevention of viral infection by interferon was defined as failure to induce cytopathologic effect for VSV, IBRV, and cytopathic BVDV and failure to detect virus immunohistochemically for cytopathic and noncytopathic BVDV. RESULTS: No evidence of cytotoxicity in either cell line was detected after incubation with interferon alfa-2a or interferon alfa-B/D. However, reduced growth rates of tissue culture cells were detected for each interferon when undiluted interferon was tested. Comparable and profound antiviral activities against cytopathic and noncytopathic BVDV were evident for each interferon. Interferon alfa-2a and interferon a-B/D had comparable antiviral activities against VSV. Neither interferon had antiviral activity against IBRV. CONCLUSIONS AND CLINICAL RELEVANCE: The safety and marked in vitro antiviral activity against noncytopathic BVDV, cytopathic BVDV, and VSV suggest that interferons alfa-2a and alfa-B/D may be useful for treatment of natural disease after infection with these viruses.     

Lessons from the cat: development of vaccines against lentiviruses

Feline immunodeficiency virus (FIV) is a natural infection of domestic cats, which produces a disease with many similarities to human immunodeficiency virus (HIV) infection in man. The virus is an important cause of morbidity and mortality in pet cats worldwide. As such an effective vaccine is desirable both for its use in veterinary medicine and also as a model for the development of an HIV vaccine. A large number of candidate vaccines have been tested against feline immunodeficiency virus. These include inactivated virus and infected cell vaccines, DNA and viral vectored vaccines, subunit and peptide vaccines and vaccines using bacterial vectors. Ultimately, the development of inactivated virus and infected cell vaccines led to the release of the first licensed vaccine against FIV, in 2002. This review highlights some of the difficulties associated with the development of lentiviral vaccines and some of the lessons that have been learned in the FIV model that are of particular relevance to the development of HIV vaccines.     

The evolution of bovine viral diarrhea: a review

The economic importance of bovine viral diarrhea is increasing with the emergence of seemingly more virulent viruses, as evidenced by outbreaks of hemorrhagic syndrome and severe acute bovine viral diarrhea beginning in the 1980s and 1990s. It appears that evolutionary changes in bovine viral diarrhea virus were responsible for these outbreaks. The genetic properties of the classical bovine viral diarrhea virus that contribute to the basis of current diagnostic tests, vaccines, and our understanding of pathogenic mechanisms are now being reevaluated because of these "new" virus strains. This shift in virulence has confounded both nomenclature and the significance of current bovine viral diarrhea virus categorization. The purpose of this review is to summarize our current understanding of bovine viral diarrhea virus with a chronological review of prevailing scientific tenets and practices as described in clinical and scientific North American veterinary journals and textbooks. The first part of this review describes how we have arrived at our current understanding of the viruses, the diseases, and their nomenclature. The second part of the review deals with current concepts in virology and how these concepts may both explain and predict bovine viral diarrhea virus pathogenesis. By reviewing how knowledge of bovine viral diarrhea has evolved and the theories of how the virus itself is able to evolve, the interpretation of diagnostic tests are more effectively utilized in the control and treatment of bovine viral diarrhea virus associated disease.     

Immunomodulation and immunodeficiency

This article briefly reviews the concepts of immunodeficiency and immunomodulation as they relate to selected skin diseases in the dog and cat. Immunodeficiency states are uncommon and may be associated with a subnormal or down-regulated immune system, including humoral deficiencies, such as IgA, and abnormal lymphocyte or neutrophil function. Establishing a causal relationship between a skin disease and presumed immunodeficient state has been difficult due to the rarity of such conditions, and the limited nature of the techniques used to characterise the immune system response. Severe combined immunodeficiency in dogs is a well characterised primary immunodeficiency state involving lymphocytes; retrovirus infection in cats may lead to an acquired immunodeficient state with some association with certain dermatological conditions although it remains unclear that infection is causally linked with disease. Immunomodulation usually implies stimulating the immune system along a beneficial pathway. Such a therapeutic approach may involve a wide variety of agents, for example intravenous immunoglobulin. There are few randomised controlled trials with veterinary patients that unequivocally demonstrate beneficial responses to immunomodulatory agents. Interferons are cytokines of major interest in human and veterinary medicine for their antiviral, anti-tumour and immunomodulatory effects. The advent of veterinary-licensed products containing recombinant interferon may enable demonstration of the efficacy of interferons for conditions such as canine papillomatosis and feline eosinophilic granuloma complex. Canine pyoderma has been treated with a number of presumed immunomodulatory agents with limited success. With more detailed knowledge of the pathogenesis of pyoderma it may be possible to develop efficacious immunomodulators.     

Comprehensive network map of transcriptional activation of chicken type I IFNs and IFN-stimulated genes

Chicken type I interferons (type I IFNs) are key antiviral players of the chicken immune system and mediate the first line of defense against viral pathogens infecting the avian species. Recognition of viral pathogens by specific pattern recognition receptors (PRRs) induce chicken type I IFNs expression followed by their subsequent interaction to IFN receptors and induction of a variety of IFN stimulated antiviral proteins. These antiviral effectors establish the antiviral state in neighboring cells and thus protect the host from infection. Three subtypes of chicken type I IFNs; chIFN-α, chIFN-β, and a recently discovered chIFN-κ have been identified and characterized in chicken. Chicken type I IFNs are activated by various host cell pathways and constitute a major antiviral innate defense in chicken. This review will help to understand the chicken type 1 IFNs, host cellular pathways that are involved in activation of chicken type I IFNs and IFN stimulated antiviral effectors along with the gaps in knowledge which will be important for future investigation. These findings will help us to comprehend the role of chicken type I IFNs and to develop different strategies for controlling viral infection in poultry.     

Viral metagenomics as an emerging and powerful tool in veterinary medicine

New diseases continue to emerge in both human and animal populations, and the importance of animals, as reservoirs for viruses that can cause zoonoses are evident. Thus, an increased knowledge of the viral flora in animals, both in healthy and diseased individuals, is important both for animal and human health. Viral metagenomics is a culture-independent approach that is used to investigate the complete viral genetic populations of a sample. This review describes and discusses the different possible steps of a viral metagenomic study utilizing sequence-independent amplification, high-throughput sequencing, and bioinformatics to identify viruses. With this technology, multiple viruses can be detected simultaneously and novel and highly divergent viruses can be discovered and genetically characterized for the first time. This review also briefly discusses the applications of viral metagenomics in veterinary science and lists some of the viruses discovered within this field.     

Antiviral therapy for ocular viral disease.

Ophthalmic manifestations of viral disease are commonly encountered in veterinary practice. Although the number of antiviral agents is rapidly increasing, the efficacy of many of these drugs against animal viral pathogens may not be known. Furthermore, some of these newer medications may, in fact. be toxic to animal patients. Continued research on the efficacy of these medications in treating viral diseases of veterinary importance is warranted.A thorough review of the ever-growing body of literature is imperative before instituting any new or unknown antiviral therapy.At this time, feline HSV-1 infections remain the most well understood of the ocular viral infections that veterinary practitioners may be called on to treat. Ironically, the number of antiviral agents proven to be effective in naturally occurring clinical cases of FHV-I remains quite limited. With new medications being investigated, this paucity of information on efficacious antiviral therapeutic agents will hopefully improve.     

Applications of DNA amplification techniques in veterinary diagnostics

An overview of the principles of the polymerase chain reaction, ligase chain reaction, self-sustained sequence replication and Q replicase is given. The application of these methods for the diagnosis of veterinary infectious and hereditary diseases as well as for other diagnostic purposes is discussed and comprehensive tables of reported assays are provided. Specific areas where these DNA-based amplification methods provide substantial advantages over traditional approaches are also highlighted. With regard to PCR-based assays for the detection of viral pathogens, this article is an update of a previous review by Belák and Ballagi-Pordány (1993).These two authors contributed equally to this review and are listed in alphabetical order.     

Treatment of canine hemangiosarcoma: 2000 and beyond

Canine hemangiosarcoma (HSA) is an aggressive and malignant neoplasia with a grave prognosis. Surgery and chemotherapy have limited success in prolonging survival times and increasing quality of life in dogs with HSA. Advances in medical oncology are resulting in increased survival rates and a better quality of life for veterinary cancer patients. An understanding of mechanisms of metastasis has led to the development of new treatments designed to delay or inhibit tumor spread. Promising new treatment options include novel delivery systems (inhalation or intracavitary chemotherapy); use of immunomodulators such as liposome-encapsulated muramyl tripeptide-phosphatidylethanolamine; antimetastatic agents such as inhibitors of angiogenesis (interferons, thalidomide), matrix metalloproteinase inhibitors, and minocycline; dietary modifications; and gene therapy. Inhibitors of angiogenesis seem to be safe and, unlike conventional chemotherapy, do not induce drug resistance. Although many of the newer approaches are still under development and review, the use of multimodality therapy incorporating innovative treatment modalities may offer the best therapeutic option for dogs affected with HSA.     

Quality documentation challenges for veterinary clinical pathology laboratories

An increasing number of veterinary laboratories worldwide have obtained or are seeking certification based on international standards, such as the International Organization for Standardization/International Electrotechnical Commission 17025. Compliance with any certification standard or quality management system requires quality documentation, an activity that may present several unique challenges in the case of veterinary laboratories. Research specifically addressing quality documentation is conspicuously absent in the veterinary literature. This article provides an overview of the quality system documentation needed to comply with a quality management system with an emphasis on preparing written standard operating procedures specific for veterinary laboratories. In addition, the quality documentation challenges that are unique to veterinary clinical pathology laboratories are critically evaluated against the existing quality standards and discussed with respect to possible solutions and/or recommended courses of action. Documentation challenges include the establishment of quality requirements for veterinary tests, the use or modification of human analytic methods for animal samples, the limited availability of quality control materials satisfactory for veterinary clinical pathology laboratories, the limited availability of veterinary proficiency programs, and the complications in establishing species-specific reference intervals.     

Viral interference with MHC class I antigen presentation pathway: the battle continues

CD8+ cytotoxic T lymphocytes (CTLs) play a critical role in the defense against viral infections. In general, CD8+ CTLs recognize antigenic peptides in the context of the major histocompatibility complex (MHC) class I molecule. The MHC class I molecules are expressed on almost all the nucleated cells in the body. The trimolecular complex consisting of the class I heavy chain, beta2-microglobulin and the peptide are generated by the MHC class I antigen presentation pathway. This pathway is designed to sample the intracellular milieu and present the information to the CTLs trafficking the area. This rigorous sampling of intracellular environment enables the CTLs to quickly identify and eliminate the cells that synthesize non-self proteins as a result of a viral infection. Many viruses, including several viruses of veterinary importance, have evolved astounding strategies to interfere with the MHC class I antigen presentation pathway, as a means of evading the CTL response of the host. This review focuses on the diverse mechanisms of viral evasion of the MHC class I antigen presentation pathway with particular emphasis on viruses of veterinary importance.     

Pharmacology of the fluoroquinolones: a perspective for the use in domestic animals

The fluoroquinolones are a class of compounds that comprise a large and expanding group of synthetic antimicrobial agents. Structurally, all fluoroquinolones contain a fluorine molecule at the 6-position of the basic quinolone nucleus. Despite the basic similarity in the core structure of these molecules, their physicochemical properties, pharmacokinetic characteristics and microbial activities can vary markedly across compounds. The first of the fluoroquinolones approved for use in animals, enrofloxacin, was approved in the late 1980s. Since then, five other fluoroquinolones have been marketed for use in animals in the United States, with others currently under investigation. This review focuses on the use of fluoroquinolones within veterinary medicine, providing an overview of the structure-activity relationship of the various members of the group, the clinical uses of fluoroquinolones in veterinary medicine, their pharmacokinetics and potential interspecies differences, an overview of the current understanding of the pharmacokinetic/pharmacodynamic relationships associated with fluoroquinolones, a summary of toxicities that have been associated with this class of compounds, their use in both in human and veterinary species, mechanisms associated with the development of microbial resistance to the fluoroquinolones, and a discussion of fluoroquinolone dose optimization. Although the review contains a large body of basic research information, it is intended that the contents of this review have relevance to both the research scientist and the veterinary medical practitioner.     

Use of oromucosally administered interferon-alpha in the prevention and treatment of animal diseases

Interferon-alpha (IFN-alpha) is well known as a clinically effective antiviral and antineoplastic therapeutic agent. It has also been shown to have immunoregulatory properties. IFN-alpha stimulates a cell-mediated innate immune response and then participates in the transition of the initial host innate response to an effective adaptive immune response. IFN-alpha is produced in small quantities in nasal secretions during viral infections, prompting many authors to suggest that low-dose oromucosal administration of IFN-alpha effectively mimics nature. Moreover, the injectable high-dose interferon therapy currently approved for various human disorders causes numerous side effects. By contrast, oromucosal administration of IFN-alpha is not associated with toxic effects. Another distinct advantage is ease of administration: the IFN can be dissolved in drinking water or administered by nebulization to the oral or nasal cavity. This review describes the current state of knowledge concerning orally administered IFN-alpha, of both human and animal origin, as a prophylactic or therapeutic agent in veterinary medicine. We present the effects of IFN-alpha in such animals as cattle, pigs, horses, cats, dogs and chickens, and attempt to explain its mechanism of action following oromucosal administration. It is hoped that this review of the medical literature on the use of IFN-alpha in animals will give practitioners a better understanding of the challenges and benefits of using this interesting cytokine in clinical practice.     

INVITED REVIEW—NEUROIMAGING RESPONSE ASSESSMENT CRITERIA FOR BRAIN TUMORS IN VETERINARY PATIENTS

The evaluation of therapeutic response using cross‐sectional imaging techniques, particularly gadolinium‐enhanced MRI, is an integral part of the clinical management of brain tumors in veterinary patients. Spontaneous canine brain tumors are increasingly recognized and utilized as a translational model for the study of human brain tumors. However, no standardized neuroimaging response assessment criteria have been formulated for use in veterinary clinical trials. Previous studies have found that the pathophysiologic features inherent to brain tumors and the surrounding brain complicate the use of the response evaluation criteria in solid tumors (RECIST) assessment system. Objectives of this review are to describe strengths and limitations of published imaging‐based brain tumor response criteria and propose a system for use in veterinary patients. The widely used human Macdonald and response assessment in neuro‐oncology (RANO) criteria are reviewed and described as to how they can be applied to veterinary brain tumors. Discussion points will include current challenges associated with the interpretation of brain tumor therapeutic responses such as imaging pseudophenomena and treatment‐induced necrosis, and how advancements in perfusion imaging, positron emission tomography, and magnetic resonance spectroscopy have shown promise in differentiating tumor progression from therapy‐induced changes. Finally, although objective endpoints such as MR imaging and survival estimates will likely continue to comprise the foundations for outcome measures in veterinary brain tumor clinical trials, we propose that in order to provide a more relevant therapeutic response metric for veterinary patients, composite response systems should be formulated and validated that combine imaging and clinical assessment criteria.     

A feline retrovirus induced T-lymphoblastoid cell-line that produces an atypical alpha type of interferon

A cell-line, designated LSA-1, was derived from a thymic lymphosarcoma that occurred in a cat with experimentally induced feline leukemia virus (FeLV) infection. LSA-1 cells possessed surface receptors and antigens of normal T-lymphocytes, but were unresponsive to interleukin-2 stimulation. The LSA cell-line was found to constitutively produce and release an interferon into the culture supernatants. Production of this interferon was enhanced in certain clones of the original LSA-1 cell lines. The interferon produced by LSA-1 cells and some of its clones was compared to the standard alpha, beta, and gamma interferons of cats. Unlike alpha and beta interferons, which were acid, SDS, and heat stable, LSA interferon was acid labile and SDS and heat stable. In comparison, standard feline gamma interferon was acid, SDS, and heat labile. LSA interferon had a molecular weight of 20,000 daltons, compared to 17-19,000 daltons for gamma, 19-25,000 for beta, and 25-45,000 daltons for alpha interferons. Standard feline interferons were active only on cat cell lines, with the exceptions of alpha interferon, which also reacted with MDCK canine cells. LSA interferon resembled the standard feline alpha interferon because it also reacted with feline and canine cells. It was concluded that LSA interferon was an atypical acid labile alpha interferon, resembling in this respect the abnormal alpha interferon seen in humans with AIDS and SLE, and mice with retrovirus infections. LSA-1 cells produced high levels of FeLV structural proteins but very little infectious virus. This effect was due to endogenously produced interferon; LSA cell clones that were selected for low interferon production produced much higher levels of infectious FeLV than parent cells or clones selected for high interferon production. Cat cells pretreated with LSA or with standard feline alpha and beta interferons, and then infected with FeLV, produced high levels of FeLV proteins but very little infectious virus.     

Prospects for molecular vaccines in veterinary parasitology

Despite the profound developments in recombinant DNA technology there is only one marketed recombinant vaccine (for human viral hepatitis B). The development of others proceeds with great difficulty. Molecular vaccines against veterinary parasites are at the utmost pole of complexity in the spectrum of potential vaccines since these parasites are complex eukaryotic organisms, often dwelling at mucosal surfaces where anamnestic responses are problematic, where the immunogenicity of the parasite components is poorly understood and where the effector mechanisms of immunity are unresolved. Cloning a "protective" gene is only the first step, and perhaps the easiest, in a long process which will be necessary to develop vaccines against parasites. Additional steps will involve comprehensive analyses of the immunological responses to ensure that vaccine antigens contain the correct epitopes to induce appropriate immune effector mechanisms for parasite elimination and immunological memory and that these responses are not genetically restricted. The great expectations for recombinant vaccinia-based vaccines must be modified substantially in the light of recent evidence indicating immunological and other constraints on this approach. The use of anti-idiotype vaccines is an underexplored opportunity for practical parasite vaccines since they have several potentially important advantages. The need to include T cell antigenic peptides in peptide vaccines to extend the range of genetic responsiveness and to induce anamnestic responses is now clear. New algorithms for the prediction of such sites exist and these can be tested experimentally with synthetic peptides. There are no major technical obstacles to the development of vaccines for parasites which cannot be overcome. However substantial long term basic research is needed over a range of disciplines to achieve this worthwhile objective.     

猪Ⅰ型干扰素融合表达及其抗病毒活性检测

采用重叠延伸PCR(splicing by overlap extension PCR,SOE-PCR)技术将猪I型干扰素PoIFN-α和PoIFN-β成熟肽基因进行连接,构建表达载体pET30a-PoIFN-α/β进行融合表达,利用细胞病变抑制试验检测融合干扰素rPoIFN-α/β抗病毒活性,并与非融合干扰素rPoIFN-α和rPoIFN-β进行比较分析。结果表明,在PK-15细胞上,融合干扰素rPoIFN-α/β表现出较强的抗病毒活性,其对VSV、PRRSV、CSFV、PRV、PPV、PASTV、PEDV和TGEV的抗病毒活性明显高于非融合干扰素,体现了一定的叠加效应,可以用于猪病毒性疾病的防治。     

Myasthenia gravis in dogs with an emphasis on treatment and critical care management

Objective – To review the human and veterinary literature on the pathophysiology of myasthenia gravis (MG) and describe treatment options for clinical use in people and animals. Data Sources – Human and veterinary clinical reports, studies and reviews, textbooks, and recent research findings in MG from 1996 present, with a focus on treatment and patient management. Human Data Synthesis – MG is a well‐described condition in people with new research and treatment options available. Many of the newest therapeutic options available in veterinary medicine for MG are based on current strategies used in people with this condition. Seronegative MG is well described in people and provides insight to clinical cases encountered in veterinary medicine when the index of suspicion is high though serologic tests are negative. Veterinary Data Synthesis – Previous studies in veterinary medicine focused on the use of acetylcholinesterase inhibitors as the main form of treatment in canine MG. Recent studies, mainly case series and case reports, emphasize the use of immunomodulatory treatments as an alternative for long‐term treatment. However, there are no randomized, controlled studies on treatment with immunomodulatory therapy for MG in dogs available to assess the efficacy of this treatment strategy. Conclusions – Although early recognition of clinical signs is most important in the outcome of patients with MG, further understanding the pathophysiology of MG may lead to earlier diagnosis and novel treatment strategies. The discovery of additional autoantibodies against striated muscle proteins in dogs, should enhance our understanding of diseases affecting the neuromuscular junction. In addition, clinical data for canine MG could be applied to other autoimmune disorders.     

Cystatin C: A New Renal Marker and Its Potential Use in Small Animal Medicine

The occurrence of chronic kidney disease is underestimated in both human and veterinary medicine. Glomerular filtration rate (GFR) is considered the gold standard for evaluating kidney function. However, GFR assessment is time‐consuming and labor‐intensive and therefore not routinely used in practice. The commonly used indirect GFR markers, serum creatinine (sCr) and urea, are not sufficiently sensitive or specific to detect early renal dysfunction. Serum cystatin C (sCysC), a proteinase inhibitor, has most of the properties required for an endogenous GFR marker. In human medicine, numerous studies have evaluated its potential use as a GFR marker in several populations. In veterinary medicine, this marker is gaining interest. The measurement is easy, which makes it an interesting parameter for clinical use. This review summarizes current knowledge about cystatin C (CysC) in humans, dogs, and cats, including its history, assays, relationship with GFR, and biological and clinical variations in both human and veterinary medicine.