Treatment of canine parvoviral enteritis with interferon-omega in a placebo-controlled challenge trial

Transcriptional Differential Analysis of Nitazoxanide-Mediated Anticanine Parvovirus Effect in F81 Cells

Canine parvovirus (CPV) is a single-stranded DNA virus that can cause typical hemorrhagic enteritis, and it is one of the common canine lethal viruses. In previous studies, we screened the Food and Drug Administration (FDA)'s drug library and identified nitazoxanide (NTZ), which has anti-CPV capabilities. To investigate the potential antiviral mechanisms, we first reconfirmed the inhibitory effect of NTZ on the CPV by inoculating with different doses and treating for different lengths of time. Then, the differences in the transcription levels between the 0.1%-DMSO-treated virus group and the NTZ-treated virus group were detected using RNA-seq, and a total of 758 differential expression genes (DEGs) were finally identified. Further Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses of the DEGs revealed that these genes are involved in a variety of biological processes and/or signaling pathways, such as cell cycle, mitosis and cell proliferation and differentiation. A protein-protein interaction (PPI) analysis further identified hub genes associated with cell cycle and division among the DEGs. In addition, the expression levels of some of the enriched genes were detected, which were consistent with the high-throughput sequencing results. Moreover, when the cell cycle was regulated with cell cycle checkpoint kinase 1 (Chk1) inhibitor MK-8776 or Prexasertib HCl, both inhibitors inhibited the CPV. In summary, the transcriptome differential analysis results presented in this paper lay the foundation for further research on the molecular mechanism and potential targets of NTZ anti-CPV.

Clinical and inflammatory response to antiviral treatments in dogs with parvoviral enteritis

BACKGROUND

Canine parvoviral enteritis (CPE) is a fatal disease worldwide. The treatment of CPE is based mainly on supportive and symptomatic treatment. Antiviral addition to the treatment may result in a higher survival.

OBJECTIVES

This study evaluated the effects of antiviral treatments with a standardized treatment (ST) on the clinical and inflammatory response of dogs with naturally occurring CPE.

METHODS

Twenty-eight dogs with CPE caused by canine parvovirus type 2 were divided randomly into treatment groups. The ST group received fluid, antibiotic, antiemetic, and deworming treatments. The antiviral treatment groups received the same ST with an additional antiviral drug, recombinant feline interferon omega (rFeIFN-ω), oseltamivir (OSEL) or famciclovir (FAM).

RESULTS

Compared to the healthy control, the tumor necrosis factor-α, interleukin-1β, interferon (IFN)-α, IFN-γ, haptoglobin, and C-reactive protein values were high (p < 0.05) on day zero. At presentation, mild lymphopenia, neutropenia, and a high neutrophil to lymphocyte (LYM) ratio (NLR) were also observed. Adding rFeIFN-ω to the ST produced the best improvement in the clinical score with a decreased NLR, while leucocytes remained low and inflammatory markers stayed high on day three. The survival rates of the groups were 85.7% in ST+IFN, 71.4% in ST+OSEL, 71.4% in ST+FAM, and 57.1% in ST groups on day seven.

CONCLUSIONS

Antiviral drugs may be valuable in treating CPE to improve the clinical signs and survival. In addition, the decrease in NLR in favor of LYM may be an indicator of the early prognosis before the improvement of leukocytes, cytokines, and acute phase proteins in CPE.

Canine parvovirus-2: An Emerging Threat to Young Pets

Canine parvovirus-2 (CPV-2) is a highly contagious and key enteropathogen affecting the canine population around the globe by causing canine parvoviral enteritis (CPVE) and vomition. CPVE is one of the the leading causes of morbidity and mortality in puppies and young dogs. Over the years, five distinct antigenic variants of CPV-2, namely CPV-2a, CPV-2b, new CPV-2a, new CPV-2b, and CPV-2c, have emerged throughout the world. CPV-2 infects a diverse range of wild animals, and the newer variants of CPV-2 have expanded their host range to include felines. Despite the availability of highly specific diagnostics and efficacious vaccines, CPV-2 outbreaks have been reported globally due to the emergence of newer antigenic variants, expansion of the viral host range, and vaccination failures. The present chapter describes the latest information pertaining to virus properties and replication, disease manifestations in animals, and an additional recent updates on diagnostic, prevention and control strategies of CPV-2.

[Use of antimicrobials in acute canine diarrhea - overview of potential risks, indications and alternatives]

In Germany, antibiotics are frequently used in dogs with gastrointestinal disorders such as acute diarrhea. In line with global efforts to limit antibiotic use, this literature review aims to provide a guideline for the rational and judicious use of antibiotics in acute canine diarrhea. Antibiotics can lead to gastrointestinal side effects and may exert a negative influence on the intestinal microbiota in addition to increasing the occurrence of resistant bacteria. There is also evidence that chronic immunological diseases may be triggered by the administration of antibiotics. Therefore, these should not be administered in uncomplicated acute diarrhea without signs of sepsis or systemic inflammatory reaction. In addition, enteropathogenic bacteria usually do not play a role in the etiology of acute diarrhea. For select clinical entities such as acute hemorrhagic diarrhea syndrome, antibiotic therapy should only be recommended in cases displaying signs of bacterial translocation with subsequent sepsis. In the case of parvovirosis, on the other hand, the administration of antibiotics is unavoidable due to the immunological incompetence of the dog caused by the accompanying severe neutropenia.

Interferon therapies in small animals

Interferons (IFNs) are cytokines that play an important role in the immune response of animals and humans. A number of studies reviewed here have evaluated the use of human, canine and feline IFNs as treatments for infectious, inflammatory and neoplastic disease in dogs and cats. Recombinant canine IFN-γ is deemed an efficacious therapy for canine atopic dermatitis. Recombinant feline IFN-ω is effective against canine parvoviral enteritis and has also been recommended for canine atopic dermatitis. Based on limited evidence, recombinant canine IFN-α could be a topical treatment option for dogs with gingivitis and keratoconjunctivitis sicca. Conclusive evidence is lacking for other diseases and large randomised controlled trials are needed before IFNs can be recommended for other indications.

Update on Canine Parvoviral Enteritis

Canine parvoviral enteritis is one of the most common causes of morbidity and mortality in dogs worldwide. Tests can detect viral antigen in feces, and characteristic decreases in total leukocyte, neutrophil, and lymphocyte counts can increase the index of suspicion in affected cases and can be used to prognosticate morbidity and mortality. The standard of care for infected animals includes IV crystalloid and sometimes colloid fluids, antiemetics, broad-spectrum antibiotics, and early enteral nutrition. Vaccination induces protective immunity in most dogs. Vaccination, along with limiting exposure in young puppies, is the most effective means of preventing parvoviral enteritis in dogs.

Canine immunoglobulin F(ab')2 fragments protect cats against feline parvovirus virus infection

Feline parvovirus virus (FPV) causes severe diarrhea and leukopenia in felines, and threatening the health of wild and domestic felines. Currently, specific drugs to treat FPV have not yet been developed. In this study, IgG was extracted from inactivated FPV-immunized dog sera. Canine F(ab')₂ fragments were obtained from pepsin-digested IgG and then purified by protein-G column chromatography. The results showed that canine immunoglobulin F(ab')₂ fragments showed efficient neutralizing activity in vitro against FPV and had therapeutic and prophylactic effects in FPV infected cats. The anti-FPV-specific F(ab')₂ fragment can significantly alleviate the clinical symptoms of FPV infected cats and reduce the viral loads of the intestinal tract. These results indicated that the F(ab')₂ fragment prepared from inactivated FPV-immunized felines may be used as a prophylactic and therapeutic agent for diseases caused by FPV.

Clinical evaluation of hyperimmune plasma for treatment of dogs with naturally occurring parvoviral enteritis

OBJECTIVE

To evaluate the clinical efficacy of a single infusion of hyperimmune plasma (HIP) in dogs with canine parvovirus (CPV).

DESIGN

Prospective, randomized, placebo-controlled clinical trial.

SETTING

University teaching hospital.

ANIMALS

Client-owned dogs with naturally occurring CPV.

INTERVENTIONS

Dogs presenting for CPV treatment (n = 31) underwent cardiovascular resuscitation and were randomized to receive a single dose of either HIP (10 mL/kg IV) or placebo (0.9% sodium chloride [10 mL/kg IV]) during the first 6 hours of hospitalization. All dogs were treated with a standardized treatment protocol (IV fluid therapy [120 mL/kg/d isotonic crystalloids], cefoxitin [30 mg/kg IV q 8 h], maropitant [1 mg/kg IV q 24 h], and buprenorphine [0.01-0.02 mg/kg IV q 8 h]) until hospital discharge.

MEASUREMENTS AND MAIN RESULTS

Dogs treated with HIP (n = 16) demonstrated a lower shock index at 24 hours (median = 0.77, range: 0.5-1.5) than those treated with placebo (n = 15, median = 1.34, range: 0.5-1.7; P = 0.02). Plasma lactate concentration was lower at 24 hours in HIP-treated dogs (median = 1.3 mmol/L, range: 0.9-3.4 mmol/L) than in placebo-treated dogs (median = 2.1 mmol/L, range: 1.1-3.4 mmol/L; P = 0.01). There was no difference in duration of hospitalization when comparing HIP-treated dogs (median = 3.2 days, range: 0.83-10 days) to placebo-treated dogs (median = 2.83 days, range: 1-8.38 days; P = 0.35). Survival was 16 of 16 (100%) for the HIP group and 14 of 15 (93.3%) for the placebo group (P = 0.32).

CONCLUSIONS

HIP at 10 mL/kg IV administered to dogs with CPV within the first 6 hours of hospitalization improves markers of shock during the initial 24 hours of hospitalization. No effects were observed on duration of hospitalization or mortality; however, this study was underpowered to evaluate these effects. HIP was well tolerated in this population of critically ill dogs.

Antiviral Effects of Hydroxychloroquine and Type I Interferon on In Vitro Fatal Feline Coronavirus Infection

Feline infectious peritonitis (FIP) is a viral disease with a high morbidity and mortality by the FIP virus (FIPV, virulent feline coronavirus). Several antiviral drugs for FIP have been identified, but many of these are expensive and not available in veterinary medicine. Hydroxychloroquine (HCQ) is a drug approved by several countries to treat malaria and immune-mediated diseases in humans, and its antiviral effects on other viral infections (e.g., SARS-CoV-2, dengue virus) have been confirmed. We investigated whether HCQ in association with interferon-ω (IFN-ω) is effective for FIPV in vitro. A total of 100 μM of HCQ significantly inhibited the replication of types I and II FIPV. Interestingly, the combination of 100 μM of HCQ and 10⁴ U/mL of recombinant feline IFN-ω (rfIFN-ω, veterinary registered drug) increased its antiviral activity against type I FIPV infection. Our study suggested that HCQ and rfIFN-ω are applicable for treatment of FIP. Further clinical studies are needed to verify the combination of HCQ and rIFN-ω will be effective and safe treatment for cats with FIP.

Survival estimates and outcome predictors for shelter cats with feline panleukopenia virus infection

OBJECTIVE To determine survival estimates and outcome predictors for shelter cats with feline panleukopenia virus (FPV) infection. DESIGN Retrospective cohort study. ANIMALS 177 shelter cats with FPV infection. PROCEDURES Medical records of cats treated for FPV infection from 2011 through 2013 were reviewed to collect information pertaining to signalment; history; results of physical examination, CBC, serum biochemical analysis, and blood gas analysis; and treatments (antimicrobials, antiparasitics, antivirals, antiemetics, analgesics, crystalloid or colloid solutions, and blood products). Survival time and outcome predictors were determined by means of Kaplan-Meier estimation, logistic regression, and mixed-model ANOVA. RESULTS Median survival time after hospital admission was 3 days; 20.3% (36/177) of cats survived to discharge from the hospital. Risk of nonsurvival was greater in cats with (vs without) signs of lethargy, rectal temperature < 37.9°C (I00.2°F), or low body weight at hospital admission. Lower (vs higher) leukocyte count on days 3,4, and 7 of hospitalization, but not at admission, was associated with nonsurvival. Amoxicillin-clavulanic acid, antiparasitics, and maropitant but not interferon-ω were associated with survival, whereas glucose infusion was associated with nonsurvival. CONCLUSIONS AND CLINICAL RELEVANCE Results suggested that FPV infection carried a poor prognosis for shelter cats. Several variables measured at admission or during hospitalization were associated with outcome. Remarkably and contrary to the existing literature, leukopenia at admission had no association with outcome, possibly owing to early prevention of complications.

Feline Panleukopenia: A Re-emergent Disease

Feline panleukopenia (FPL) is caused by a Carnivore protoparvovirus infection. Feline parvovirus (FPV) causes most cases. When Canine parvovirus 2 (CPV-2) first emerged, it could not replicate in cats. All current CPV variants (CPV-2a-c) can infect cats to cause subclinical disease or FPL. Feline panleukopenia has re-emerged in Australia in shelter cats associated with failure to vaccinate. Parvoviruses can remain latent in mononuclear cells post-infection. Molecular methods such as polymerase chain reaction are used to determine the infecting strain. Current perspectives on causes, epidemiology, diagnosis, treatment, prognostic indicators, and management of outbreaks in shelters are reviewed.

Oncolytic Viruses for Canine Cancer Treatment

Oncolytic virotherapy has been investigated for several decades and is emerging as a plausible biological therapy with several ongoing clinical trials and two viruses are now approved for cancer treatment in humans. The direct cytotoxicity and immune-stimulatory effects make oncolytic viruses an interesting strategy for cancer treatment. In this review, we summarize the results of in vitro and in vivo published studies of oncolytic viruses in different phases of evaluation in dogs, using PubMed and Google scholar as search platforms, without time restrictions (to date). Natural and genetically modified oncolytic viruses were evaluated with some encouraging results. The most studied viruses to date are the reovirus, myxoma virus, and vaccinia, tested mostly in solid tumors such as osteosarcomas, mammary gland tumors, soft tissue sarcomas, and mastocytomas. Although the results are promising, there are issues that need addressing such as ensuring tumor specificity, developing optimal dosing, circumventing preexisting antibodies from previous exposure or the development of antibodies during treatment, and assuring a reasonable safety profile, all of which are required in order to make this approach a successful therapy in dogs.

Bocavirus-Nachweis bei 4 Wochen alten Welpen mit akutem Durchfall

Zwei 4 Wochen alte, weibliche Dobermann-Welpen wurden mit akutem Durchfall und Erbrechen vorgestellt. Zusätzlich zeigten sie Niesen und Nasenausfluss. Aufgrund der klinischen Präsentation und einer Neutropenie bestand der hochgradige Verdacht einer Parvovirose. Die Tiere blieben mehrere Tage hospitalisiert und wurden symptomatisch therapiert. Eine parasitologische Kotuntersuchung sowie eine virologische Untersuchung des Kots auf eine Parvovirusinfektion (Polymerasekettenreaktion [PCR] und Immunelektronenmikroskopie) verliefen negativ. Mithilfe einer weiteren, neuen PCR ließ sich das Bocavirus identifizieren, sodass eine Infektion mit diesem Erreger als mögliche Diagnose infrage kommt. Dieser Fallbericht beschreibt eine noch wenig bekannte virale Welpenerkrankung mit erfolgreichem Therapieverlauf.

Interferon-omega: Current status in clinical applications

Since 1985, interferon (IFN)-ω, a type I IFN, has been identified in many animals, but not canines and mice. It has been demonstrated to have antiviral, anti-proliferation, and antitumor activities that are similar to those of IFN-α. To date, IFN-ω has been explored as a treatment option for some diseases or viral infections in humans and other animals. Studies have revealed that human IFN-ω displays antitumor activities in some models of human cancer cells and that it can be used to diagnose some diseases. While recombinant feline IFN-ω has been licensed in several countries for treating canine parvovirus, feline leukemia virus, and feline immunodeficiency virus infections, it also exhibits a certain efficacy when used to treat other viral infections or diseases. This review examines the known biological activity of IFN-ω and its clinical applications. We expect that the information provided in this review will stimulate further studies of IFN-ω as a therapeutic agent.

Type I interferons in the pathogenesis and treatment of canine diseases

Type I interferons (IFNs) such as IFN-α, IFN-β, IFN-ε, IFN-κ, and IFN-ω represent cytokines, which are deeply involved in the regulation and activation of innate and adaptive immune responses. They possess strong antiviral, antiproliferative, and immunomodulatory activities allowing their use in the therapy of different viral diseases, neoplasms, and immune-mediated disorders, respectively. Initially, treatment strategies were based on nonspecific inducers of type I IFNs, which were soon replaced by different recombinant proteins. Drugs with type I IFNs as active agents are currently used in the treatment of hepatitis B and C virus infection, lymphoma, myeloid leukemia, renal carcinoma, malignant melanoma, and multiple sclerosis in humans. In addition, recombinant feline IFN-ω has been approved for the treatment of canine parvovirus, feline leukemia virus, and feline immunodeficiency virus infections. However, the role of type I IFNs in the pathogenesis of canine diseases remains largely undetermined so far, even though some share pathogenic mechanisms and clinical features with their human counterparts. This review summarizes the present knowledge of type I IFNs and down-stream targets such as Mx and 2',5'-oligoadenylate synthetase proteins in the pathogenesis of infectious and immune-mediated canine diseases. Moreover, studies investigating the potential use of type I IFNs in the treatment of canine lymphomas, melanomas, sarcomas, and carcinomas, canine distemper virus, parvovirus, and papillomavirus infections as well as immune-mediated keratoconjunctivitis sicca and atopic dermatitis are presented. A separate chapter is dedicated to the therapeutic potential of IFN-λ, a type III IFN, in canine diseases. However, further future studies are still needed to unravel the exact functions of the different subtypes of type I IFNs and their target genes in healthy and diseased dogs and the full potential action of type I IFNs as treatment strategy.

Serum Derived Transfer Factor Stimulates the Innate Immune System to Improve Survival Traits in High Risk Pathogen Scenarios

Preclinical Research Transfer Factors (TFs) are low molecular weight (<5,000 daltons) biological response mediators. In the present study, a serum derived TF improved the ability of the recipient animal to survive high-risk infectious challenges (salmonellosis and canine parvoviral enteritis (CPV)) by altering the host's cytokine response profile. Mice mortally challenged with 5,000 colony-forming units of Salmonella experienced a group mortality of 73% while mice treated with a single 5 mg dose of the TF demonstrated a significant decrease in morbidity (7%, p ≤ 0.01). The splenic bacterial load in untreated mice was over 10,000 times higher than that in the TF treated mice. Twenty-four hours post-administration, the treated murine population expressed a rapid temporal increase in serum IL-6 (26-fold) and INF-γ (77-fold) concentrations. IL-6 can act as a critical signal regulating action against bacterial pathogens. A comparative double-blind study performed using dogs confirmed to be undergoing a canine parvovirus challenge showed that when conventional supportive therapy was supplemented with a single 5 mg TF dose there was a reduction (p ≤ 0.01) in group mortality (68% of the TF treated group survived versus 32% of the placebo group), an observation consistent with the observed increase in INF-γ, a cytokine associated with promoting antiviral activity. Drug Dev Res 78 : 189-195, 2017. © 2017 Wiley Periodicals, Inc.

Efficacy of feline anti-parvovirus antibodies in the treatment of canine parvovirus infection

OBJECTIVE

This prospective, randomised, placebo-controlled, double-blinded study aimed to evaluate efficacy of commercially available feline anti-parvovirus antibodies in dogs with canine parvovirus infection.

METHODS

First, cross-protection of feline panleukopenia virus antibodies against canine parvovirus was evaluated in vitro. In the subsequent prospective clinical trial, 31 dogs with clinical signs of canine parvovirus infection and a positive faecal canine parvovirus polymerase chain reaction were randomly assigned to a group receiving feline panleukopenia virus antibodies (n=15) or placebo (n=16). All dogs received additional routine treatment. Clinical signs, blood parameters, time to clinical recovery and mortality were compared between the groups. Serum antibody titres and quantitative faecal polymerase chain reaction were compared on days 0, 3, 7, and 14.

RESULTS

In vitro, canine parvovirus was fully neutralised by feline panleukopenia virus antibodies. There were no detected significant differences in clinical signs, time to clinical recovery, blood parameters, mortality, faecal virus load, or viral shedding between groups. Dogs in the placebo group showed a significant increase of serum antibody titres and a significant decrease of faecal virus load between day 14 and day 0, which was not detectable in dogs treated with feline panleukopenia virus antibodies.

CLINICAL SIGNIFICANCE

No significant beneficial effect of passively transferred feline anti-parvovirus antibodies in the used dosage regimen on the treatment of canine parvovirus infection was demonstrated.

Molecular characterization and biological activity of bovine interferon-omega3

Bovine interferon-omega3 (BoIFN-ω3) gene was amplified from bovine liver genomic DNA, which encodes a 195-amino acid protein containing a 23-amino acid signal peptide. Analysis of the molecular characteristics revealed that BoIFN-ω3 evolving from IFN-ω, contained four cysteine residues and five alpha helices, showing that BoIFN-ω3 presented the typical molecular characteristics of type I interferon. BoIFN-ω3 exhibited antiviral and antiproliferative activities, which exerted a protective effect against VSV in several mammalian cell lines, as well as against BEV, IBRV, and BVDV in MDBK cell. Moreover, BoIFN-ω3 was shown to be highly sensitive to trypsin, but remaining stable despite changes in pH and temperature. Additionally, BoIFN-ω3 induced the transcription of Mx1, ISG15, and ISG56 genes, as well as the expression of Mx1 protein in a time-dependent manner. These findings will be useful to further study BoIFN-ω in host's defence against infectious diseases, particularly viral infections. Furthermore, results will facilitate further research on the bovine interferon family.

•

BoIFN-ω3 presents antiviral activity on several mammalian cell lines and protective effect against VSV, BEV, IBRV, and BVDV.

•

BoIFN-ω3 exhibits antiproliferative activity and insensitivity to pH and temperature.

•

BoIFN-ω3 can activate the transcription of ISGs gene, as well as the expression of Mx1 in a time-dependent manner.

Identification of Inonotus obliquus polysaccharide with broad-spectrum antiviral activity against multi-feline viruses

•

Respiratory and gastrointestinal viruses are the main causes that contribute to acute and chronic infections in cats.

•

Inonotus obliquus polysaccharides (IOPs) are a potential drug for the prevention and treatment of cancer.

•

IOP can also act as a broad-spectrum antiviral drug against feline viral diseases.

•

IOP treatment induces its inhibitory actions directly on virus particles through blocking viral binding/absorpting.

Inonotus obliquus polysaccharides (IOPs) are a potential drug for the prevention and treatment of cancer, cardiopathy, diabetes, AIDs, pancreatitis and other diseases. In this study, we found that IOP can act as a broad-spectrum antiviral drug against feline viruses in the in vitro experiment. Using cell models of feline calicivirus (FCV), we demonstrated that IOP treatment was capable of exhibiting anti-FCV strain F9 activity in cell-based assays and also showed low cytotoxicity. Investigation of the mechanism of action of the compound revealed that IOP treatment induces its inhibitory actions directly on virus particles through blocking viral binding/absorpting. The inhibitory activity against other FCV isolates from China was also identified. More importantly, we found that IOP exhibited broad-spectrum antiviral activity against the feline herpesvirus 1, feline influenza virus H3N2 and H5N6, feline panleukopenia virus and feline infectious peritonitis virus that can contribute to respiratory and gastrointestinal diseases in cats. These findings suggest that IOP may be a potential broad-spectrum antiviral drug against feline viruses.

Canine parvoviral enteritis: an update on the clinical diagnosis, treatment, and prevention

Canine parvovirus type 2 is the cause of a highly contagious acute enteritis associated with high morbidity and mortality, with very low survival rates in untreated dogs. Although severe clinical disease typically occurs in dogs younger than 6 months of age, adults with insufficient immunity may potentially be affected. In this article, the current state of knowledge is reviewed regarding the diagnostic aspects of parvoviral enteritis, with special emphasis placed on the clinical relevance of the detection of viral antigens in the feces, detection of viral antibodies in the serum, or the polymerase chain reaction-based amplification of the viral DNA in the feces. In addition, the components of the supportive and symptomatic treatment aiming to optimize the outcome of the disease in the clinical setting are thoroughly reviewed. Immunization guidelines for the prevention of the disease are also updated.

Feline parvovirus infection and associated diseases

Feline panleukopenia, caused by the single-stranded DNA virus feline parvovirus (FPV), is a highly contagious and often lethal disease of cats and other Felidae. FPV, but also canine parvovirus (CPV) can be isolated from both healthy and diseased cats. In Germany, CPV was detected in only approximately 10% of feline samples, but in Southeast Asia, reports estimated that up to approximately 80% of diseased cats were infected with CPV. Infection spreads rapidly, especially in cells with high mitotic activity, such as bone marrow, lymphoid tissue and intestinal crypt cells. Anorexia, vomiting, diarrhoea, neutropenia and lymphopenia are common in clinically affected cases. In utero or neonatal infection can result in cerebellar hypoplasia. Depending on the severity of clinical signs, mortality ranges from 25 to 100%. Effective vaccination and thorough disinfection are of the utmost importance in the prevention of disease transmission in multi-cat households and animal shelters. If clinical signs develop, supportive treatment should be commenced. The efficacy of feline recombinant interferon and FPV antibodies has not been clearly demonstrated. Commercially available vaccines should induce protective immunity when administered according to current guidelines. Recent studies suggest that in some kittens, maternally derived antibodies (MDA) can persist for much longer than has been previously recognised. FPV serum antibody tests are available, but protection status needs to be interpreted with caution in kittens with MDA and a negative titre in adult cats does not necessarily denote lack of protection.

Immunological Effects of Recombinant Feline Interferon-ω (KT-80) Administration in the Dog

The immunological effects of recombinant feline interferon-omega (rFeIFN-omega ; KT-80, Toray) were examined on administration to healthy dogs. The activities of whole blood cells, macrophages, and natural killer cells were enhanced. Moreover, the whole blood activity was examined when KT-80 was administered to dogs which had been diagnosed as having natural canine parvovirus (CPV) infection. Only some cases in which the activity increased until 3 hr post-administration survived. These results suggest that rFeIFN-omega (KT-80) treatment enhanced the cellular immunity of normal dogs, and could exert significant therapeutic effects on only natural CPV infected dogs with induced continuous immunoenhancement.

Potencial antiviral da quercetina sobre o parvovírus canino

Avaliou-se o efeito do flavonoide quercetina na replicação do parvovírus canino in vitro por meio do ensaio de determinação da atividade virucida (ensaio 1), ensaio de determinação da atividade sobre a célula (ensaio 2) e ensaio de tempo de adição das drogas em diferentes etapas do ciclo replicativo viral (ensaio 3). A quercetina apresentou significante atividade antiviral, com valores máximos de redução do título viral de 96,3% no ensaio 1, 90% no ensaio 2 e 90% no ensaio 3. Os efeitos mais expressivos ocorreram nas etapas de adsorção e penetração viral. Os resultados deste trabalho sugerem a importância da quercetina para a medicina veterinária.

Stimulation with a class A CpG oligonucleotide enhances resistance to infection with feline viruses from five different families

Domestic cats are commonly affected by viral pathogens that induce lengthy infections with fatal outcomes. Prevention of viral propagation is of primordial importance in shelters and catteries, where cats from different backgrounds have narrow contacts. Oligonucleotides (ODN) containing cytosine-phosphate-guanosine motifs of class A (CpG-A) are highly potent synthetic inducers of innate antiviral mechanisms. The aim of this study was to test their ability to modulate innate immune responses and prevent viral replication as stand-alone agents in the domestic cat. CpG-A stimulation of feline peripheral blood mononuclear cells (PBMCs) enhanced their proliferation, increased the presence of co-stimulatory molecules on their surface and influenced their gene expression profiles in an antiviral orientation. Incubation of the supernatants of CpG-A stimulated PBMCs with feline cell lines of epithelial and fibroblastic origin induced expression of the antiviral myxovirus resistance (Mx) gene in these target cells, which also showed enhanced resistance to feline viruses from five distinct families, namely Coronaviridae, Herpesviridae, Caliciviridae, Parvoviridae, and Retroviridae. Most importantly, subcutaneous administration of CpG-A in domestic cats systemically increased the expression of Mx, reaching maximal levels within 24 h. Plasma from treated cats could furthermore inhibit viral replication in vitro. Altogether, our data highlight the promising potential of CpG-A to induce a preventive antiviral state in the cat and to protect feline populations against a broad range of virus infections.

Induction of a systemic antiviral state in vivo in the domestic cat with a class A CpG oligonucleotide

The evolution of cats as a solitary species has pressured feline viruses to develop highly efficient transmission strategies, the ability to persist within the host for long periods of time and the aptitude to adapt to natural and vaccine-induced immunological pressures. These characteristics render feline viruses particularly dangerous in catteries, shelters and rescue homes, were cats from different backgrounds live in close proximity. The possibility to induce short-term resistance of newcomer cats to a broad variety of viruses could help prevent the dissemination of viruses both within and outside such facilities. Oligonucleotides (ODN) containing unmethylated cytosine phosphate guanosine (CpG) motifs stimulate innate immune responses in mammals. We have previously shown that ODN 2216, a class A CpG ODN, promotes the expression by feline immune cells of potent antiviral molecules that increase resistance of feline fibroblastic and epithelial cell lines to five common feline viruses. With the aim to test the safety and extent of the biological effects of ODN 2216 in the domestic cat, we performed an initial in vivo experiment in which two cats were injected the molecule once subcutaneously and two additional cats received control treatments. No side effects to administration of ODN 2216 were observed. Moreover, this molecule induced the expression of the myxovirus resistance (Mx) gene, a marker for the instigation of innate antiviral processes, in blood as well as in oral, conjunctival and rectal mucosa cells, indicating systemic biological activity of the molecule with protective potential at viral entry sites. Mx mRNA levels were already elevated in blood 6 h post injection of ODN 2216, reached peak levels within 24 h and returned to basal values by 96–192 h after administration of the molecule. Similar induction patterns were observed in all analyzed mucosal cells. Plasma collected from treated cats at regular intervals until 96–192 h could moreover induce Mx mRNA expression in fcwf-4 cells and increase resistance of these cells to feline calicivirus inoculation. Finally, Mx mRNA levels measured in blood correlated with the degree of viral inhibition that was induced by plasma from the same cat and the same experimental time point. Our results altogether underline the promising potential of ODN 2216 in promoting antiviral defense mechanisms and inducing temporary resistance to viral infections in vivo in the domestic cat.

Clinical evaluation of a single dose of immune plasma for treatment of canine parvovirus infection

OBJECTIVE

To evaluate the efficacy of administration of a single 12-mL dose of canine parvovirus (CPV)-immune plasma for treatment of CPV enteritis.

DESIGN

Prospective, randomized, double-blinded, placebo-controlled clinical trial.

ANIMALS

14 dogs with naturally occurring CPV enteritis.

PROCEDURES

Dogs were assigned to treatment groups on the basis of randomization tables and were administered a single i.v. dose of CPV-immune plasma (treatment group) or an equivalent volume of saline (0.9% NaCl) solution (placebo group) within 18 hours after admission to the hospital. Treatment and outcome variables evaluated included neutrophil, monocyte, and CPV counts; number of days of hospitalization; changes in body weight; and cost of treatment.

RESULTS

When dogs treated with CPV-immune plasma were compared with dogs treated with saline solution, there were no significant differences detected among neutrophil or monocyte counts, magnitude of viremia, weight change, number of days of hospitalization, or cost of treatment.

CONCLUSIONS AND CLINICAL RELEVANCE

Administration of a single 12-mL dose of immune plasma soon after the onset of CPV enteritis in dogs was not effective in ameliorating clinical signs, reducing viremia, or hastening hematologic recovery.

The innate antiviral immune system of the cat: molecular tools for the measurement of its state of activation

The innate immune system plays a central role in host defence against viruses. While many studies portray mechanisms in early antiviral immune responses of humans and mice, much remains to be discovered about these mechanisms in the cat. With the objective of shedding light on early host-virus interactions in felids, we have developed 12 real-time TaqMan(®) qPCR systems for feline genes relevant to innate responses to viral infection, including those encoding for various IFNα and IFNω subtypes, IFNβ, intracellular antiviral factor Mx, NK cell stimulator IL-15 and effectors perforin and granzyme B, as well as Toll-like receptors (TLRs) 3 and 8. Using these newly developed assays and others previously described, we measured the relative expression of selected markers at early time points after viral infection in vitro and in vivo. Feline embryonic fibroblasts (FEA) inoculated with feline leukemia virus (FeLV) indicated peak levels of IFNα, IFNβ and Mx expression already 6h after infection. In contrast, Crandell-Rees feline kidney (CrFK) cells inoculated with feline herpes virus (FHV) responded to infection with high levels of IFNα and IFNβ only after 24h, and no induction of Mx could be detected. In feline PBMCs challenged in vitro with feline immunodeficiency virus (FIV), maximal expression levels of IFNα, β and ω subtype genes as well as IL-15 and TLRs 3, 7 and 8 were measured between 12 and 24h after infection, whereas expression levels of proinflammatory cytokine gene IL-6 were consistently downregulated until 48h post inoculation. A marginal upregulation of granzyme B was also observed within 3h after infection. In an in vivo experiment, cats challenged with FIV exhibited a 2.4-fold increase in IFNα expression in blood 1 week post infection. We furthermore demonstrate the possibility of stimulating feline immune cells in vitro with various immune response modifiers (IRMs) already known for their immunostimulatory properties in mice and humans, namely Poly IC, Resiquimod (R-848) and dSLIM™, a synthetic oligonucleotide containing several unmethylated CpG motifs. Stimulation of feline PBMCs with dSLIM™ and R-848 effectively enhanced expression of IFNα within 12h by factors of 6 and 12, respectively, and Poly IC induced an increase in Mx mRNA expression of 28-fold. Altogether, we describe new molecular tools and their successful use for the characterization of innate immune responses against viruses in the cat and provide evidence that feline cells can be stimulated by synthetic molecules to enhance their antiviral defence mechanisms.

Canine parvovirus

Since its emergence in 1978, canine parvoviral enteritis has remained a common and important cause of morbidity and mortality in young dogs. The continued incidence of parvoviral enteritis is partly due to the virus's capability to "reinvent" itself and evolve into new, more virulent and resistant subspecies. This article reviews current knowledge about the virus, its epidemiology, clinical manifestation, diagnosis, management, and prevention.

Use of oseltamivir in the treatment of canine parvoviral enteritis

OBJECTIVE

To determine if oseltamivir with standard therapy for canine parvoviral enteritis ameliorates disease morbidity, mortality, or both; to document significant adverse effects associated with its use.

DESIGN

Prospective, randomized, blinded, placebo-controlled clinical trial.

SETTING

University veterinary teaching hospital.

ANIMALS

Thirty-five dogs.

INTERVENTIONS

Standard therapy was administered to all dogs. Treatment dogs also received oseltamivir, while control dogs received an equivalent volume of placebo.

MEASUREMENTS AND MAIN RESULTS

Dogs were monitored daily according to a clinical scoring system, physical parameters, and diagnostic evaluations. Dogs in the treatment group gained a significant percentage of weight during hospitalization (mean, +2.6%; SD, 7.1%) versus the control dogs (mean, -4.5%; SD, 6.9%) (P=0.006). Treatment dogs did not have any significant changes in their white blood cell (WBC) count, while control dogs experienced a significant drop in their WBC counts during their initial stay. In addition, it did not appear that oseltamivir use was associated with any major adverse clinical effects.

CONCLUSIONS

While a clear advantage to the use of oseltamivir was not established, a significant weight loss during hospitalization, as well as a significant decrease in WBC count were documented in the control group. No major adverse effects were identified that could be associated with oseltamivir administration. Based on these results, the true role of oseltamivir in the treatment of parvoviral enteritis remains speculative, although it is believed that further investigation is warranted.

Molecular characterization of feline type I interferon receptor 2

The cDNA sequence of feline interferon receptor 2 (feIFNAR2) was generated using RT-PCR method in present study. This gene included 1,572 bp and encoded a 523 aminoacid (aa) protein with a 35 aa signal peptide. The deduced protein shared 61% amino acid identity to the human IFNAR2. There were two fibronectin type III (FBN-III) domains of about 110 residues in the extracellular domain. Homology modeling of feIFNAR2 presented a similar structure with other IFN receptors. The ELISA and FACS experiments demonstrated that the protein could bind to feIFN-alpha or feIFN-omega. However, antiviral activity assay found that feIFN-omega had broader species spectrum compared with feIFN-alpha. To define the functional differences, several point mutations of feIFNAR2 were constructed and the relative affinities of feIFN-alpha or feIFN-omega for feIFNAR2 and mutants were evaluated. The results suggested that feIFN-alpha and feIFN-omega had different binding sites on feIFNAR2. T75 and M77 on feIFNAR2 were hotspots for binding to feIFN-alpha, but not to feIFN-omega. These findings suggested that the cloned feline IFNAR2 interacted with both feIFN-alpha and feIFN-omega, however, not sharing the same binding sites.

Characterization and virus-induced expression profiles of the porcine interferon-omega multigene family

Interferon-omega is a member of the type I interferon family. In this work, 8 functional porcine interferon-omega genes and 4 pseudogenes present on porcine chromosome 1 were identified in the porcine genome database by BLAST scanning. Their genetic and genomic characteristics were investigated using bioinformatics tools. Then the PoIFN-omega functional subtype genes were isolated and expressed in BHK-21 cells. The PoIFN-omega subtypes possessed about 10(4) to 10(5) units of antiviral activity per milliliter. PoIFN-omega 7 had the highest antiviral activity, about 20 times that of PoIFN-omega 4, which had the lowest antiviral activity. Differential expression of the subtypes was detected in PK15 cells and porcine peripheral blood mononuclear cells (PBMCs) in response to pseudorabies virus and poly(I).poly(C). Expression of PoIFN-omega 2/-omega 6 was up-regulated to the greatest extent by virus infection.

Panleucopénie féline aiguë : à propos d’un cas traité avec succès par l’interféron-ω

La panleucopénie féline est une infection virale (due à un petit parvovirus FPV). Ce virus est très stable et capable de survivre une année à température ambiante dans les matières organiques sur un support solide. Quasiment tous les chats sensibles sont exposés et infectés au cours de leur première année de vie. La forme aiguë de la maladie est fréquente, avec hyperthermie, anorexie et léthargie, précédant de trois ou quatre jours les premiers signes cliniques. Dans la plupart des cas, la mortalité peut être évitée par un traitement symptomatique et des soins appropriés. Cependant, la maladie, dans sa forme aiguë, est souvent associée à une bactériémie chez les jeunes chats non vaccinés, pouvant se révéler mortelle. Lorsqu’un traitement symptomatique n’est pas suffisamment efficace, le recours à une thérapie antivirale pourrait être une alternative. L’interféron recombinant félin oméga a été utilisé avec succès selon un protocole d’administration décrit, le statut médical du chat étant suivi avant, pendant et après le traitement mis en place.

Feline panleukopenia. ABCD guidelines on prevention and management

OVERVIEW

Feline panleukopenia virus (FPV) infects all felids as well as raccoons, mink and foxes. This pathogen may survive in the environment for several months and is highly resistant to some disinfectants.

INFECTION

Transmission occurs via the faecal-oral route. Indirect contact is the most common route of infection, and FPV may be carried by fomites (shoes, clothing), which means indoor cats are also at risk. Intrauterine virus transmission and infection of neonates can occur.

DISEASE SIGNS

Cats of all ages may be affected by FPV, but kittens are most susceptible. Mortality rates are high - over 90% in kittens. Signs of disease include diarrhoea, lymphopenia and neutropenia, followed by thrombocytopenia and anaemia, immunosuppression (transient in adult cats), cerebellar ataxia (in kittens only) and abortion.

DIAGNOSIS

Feline panleukopenia virus antigen is detected in faeces using commercially available test kits. Specialised laboratories carry out PCR testing on whole blood or faeces. Serological tests are not recommended, as they do not distinguish between infection and vaccination.

DISEASE MANAGEMENT

Supportive therapy and good nursing significantly decrease mortality rates. In cases of enteritis, parenteral administration of a broad-spectrum antibiotic is recommended. Disinfectants containing sodium hypochlorite (bleach), peracetic acid, formaldehyde or sodium hydroxide are effective.

VACCINATION RECOMMENDATIONS

All cats - including indoor cats - should be vaccinated. Two injections, at 8-9 weeks of age and 3-4 weeks later, are recommended, and a first booster 1 year later. A third vaccination at 16-20 weeks of age is recommended for kittens from environments with a high infection pressure (cat shelters) or from queens with high vaccine-induced antibody levels (breeding catteries). Subsequent booster vaccinations should be administered at intervals of 3 years or more. Modified-live virus vaccines should not be used in pregnant queens or in kittens less than 4 weeks of age.

Oxidative stress indices in gastroenteritis in dogs with canine parvoviral infection

Gastroenteritis of viral origin has emerged as a major cause of morbidity and mortality in dogs during the last two decades. Amongst the viral etiologies responsible for gastroenteritis in dogs, canine parvovirus (CPV) is considered as the most pathogenic. The disease is characterized by hemorrhagic enteritis, bloody diarrhoea and myocarditis in young pups. The present study was carried out to examine alterations in oxidative stress indices in the erythrocytes from dogs suffering from gastroenteritis with or without canine parvoviral infection as confirmed by CPV-DNA amplification from faeces using specific primers for CPV-2 as well as CPV-2a and CPV-2b variants by polymerase chain reaction (PCR). The present investigation utilized clinical cases of dogs with signs of acute diarrhea (n = 56), and 14 more apparently healthy dogs of similar age group. Erythrocytic oxidative stress indices such as lipid peroxides level and antioxidant enzymes like superoxide dismutase and catalase activity, and blood micro-mineral (iron, copper, cobalt and zinc) status were analyzed in each dog (n = 70). The acute cases of gastroenteritis in dogs were associated with altered erythrocytic lipid peroxidation as evident by estimation of malonaldehyde (MDA) concentration. The activities of antioxidant enzymes catalase and superoxide dismutase, the first line of antioxidant defense against damaging effects of free radicals, were also altered. The alterations in oxidative stress indices were more pronounced in cases with involvement of canine parvovirus as compared to parvo-negative cases. Our results also revealed decreased blood zinc level in diarrhoea in dogs irrespective of involvement of canine parvovirus.

Evaluation of inflammation and immunity in cats with spontaneous parvovirus infection: consequences of recombinant feline interferon-omega administration

Administration of recombinant feline interferon-ω (rFeIFN) has been proposed for the prophylaxis of canine and feline parvovirosis. In the present study, the influence of the administration of rFeIFN on blood markers of inflammation (α-globulins, α₁-acid glycoprotein) and immune system activation (γ-globulins, IgG, IgM, specific anti-feline parvovirus IgG or IgM) was evaluated in a cattery developing an outbreak of feline panleukopenia due to feline parvovirus (FPV) infection few days after initial administration of rFeIFN. Kittens (n = 23) were injected with rFeIFN (1 MU/kg subcutaneoulsy, once a day for 3 days) and their blood parameters were compared with those of 17 untreated cats. Cats that survived the outbreak were vaccinated and re-sampled 1 month after the last rFeIFN administration. Time of emergence of clinical signs and survival rate were not significantly different between the two groups. Controls and treated cats surviving the infection had high levels of γ-globulins, total- and anti-FPV specific IgGs, likely due to passive transfer of maternal immunity. Compared to controls, treated kittens had lower levels of α₁-globulins and higher mean values of γ-globulins and immunoglobulins. Data from samples collected after vaccination revealed a higher level of γ-globulins, total- and anti-FPV specific IgGs in treated kittens, compared with controls, suggesting that rFeIFN stimulates antibody production. Based on this results, rFeIFN should be administered to the queen, to increase passive maternal immunity, or to kittens before introduction in a potentially contaminated environment.

Cloning and characterization of a novel feline IFN-omega

The interferons (IFNs) are a large family of multifunctional secreted protein involved in antiviral defense, cell growth regulation, and immune activation. The human IFNs are used worldwide as antiviral drugs. Here, we present cDNAs encoding 13 novel feline IFN-omega (FeIFN-omega) subtypes that share 95%-99% amino acid sequence identity. FeIFN-omega2 and FeIFN-omega4 have seven additional amino acids at position 109 that are not present in other subtypes. Sequence identity of the present FeIFN proteins encoded by the 13 subtypes is approximately 57% compared with human IFN-omega (HuIFN-omega). All 13 FeIFN-omega subtypes were expressed in Escherichia coli using a periplasmic expression system. The antiviral activity of each product was evaluated in vitro. In addition, subtype FeIFN-omega2 was cytoplasm expressed in E. coli and secretion expressed in Pichia pastoris. The purified mature recombinant protein demonstrated significant antiviral activity on both homologous and heterologous animal cells in vitro.

Feline herpes dermatitis treated with interferon omega

This case report describes the diagnosis, demonstration and treatment of feline herpes virus‐induced facial dermatitis in a cat. The cat was successfully treated with interferon omega (IFN‐ω).

Enhancement of Porcine Circovirus 2 Replication in Porcine Cell Lines by IFN-γ Before and After Treatment and by IFN-α After Treatment

Stimulation of the porcine immune system causes increased replication of porcine circovirus 2 (PCV2) in vivo. In the present study, we investigated whether various cytokines (interleukin-1 [IL-1], IL-6, IL-10, tumor necrosis factor-alpha [TNF-alpha], interferon-alpha [IFN-alpha], and IFN-gamma) are able to influence PCV2 infection in vitro. No changes were observed in IL-1, IL-6, TNF-alpha, or IL-10-treated cells. However, it was demonstrated that IFN- alpha and IFN-gamma influenced PCV2 infection in porcine kidney cells (PK-15) and porcine monocytic cells (3D4/31). IFN-gamma added to the culture medium before, during, or after inoculation increased the number of PCV2 antigen- positive cells, respectively, by 418%, 171%, and 691% in PK-15 cells and by 706%, 114%, and 423% in 3D4/31 cells. IFN-alpha pretreatment decreased the number of infected PK-15 cells. When it was added after inoculation, IFN-alpha enhanced PCV2 infection by 529% in PK-15 cells and by 308% in 3D4/31 cells. The effect of both IFNs on PCV2 infection was dose dependent and could be blocked with IFN-alpha or IFN-gamma neutralizing antibodies. Leukocyte-derived porcine IFN-gamma induced a similar effect on PCV2 infection. Treatment of PK- 15 cultures with IFN-gamma caused a 20 times higher production of progeny virus. Confocal microscopy studies showed that the enhancing effect of IFN-gamma on PCV2 infection was achieved by increased internalization of PCV2 virionlike particles (VLPs). Binding of the VLPs to the cell or expression kinetics of PCV2 proteins in infected cells were not altered by IFN-gamma treatment. To our knowledge, this study reports the first enhancement of a viral infection by treatment with type I or type II IFNs.

An update on aspects of viral gastrointestinal diseases of dogs and cats

Viruses commonly cause gastrointestinal illnesses in dogs and cats that range in severity from mild diarrhoea to malignant neoplasia. Perpetual evolution of viruses is reflected in changing disease patterns, so that familiar viruses are sometimes discovered to cause new or unexpected diseases. For example, canine parvovirus (CPV) has regained the ability to infect felids and cause a panleucopenia-like illness. Feline panleucopenia virus (FPV) has been shown to cause fading in young kittens and has recently been implicated as a possible cause of feline idiopathic cardiomyopathy. Molecular scrutiny of viral diseases sometimes permits deeper understanding of pathogenesis and epizootiology. Feline gastrointestinal lymphomas have not, in the past, been strongly associated with retroviral infections, yet some of these tumours harbour retroviral proviruses. Feline leukaemia virus (FeLV) may play a role in lymphomagenesis, even in cats diagnosed as uninfected using conventional criteria. There is strong evidence that feline immunodeficiency virus (FIV) can also be oncogenic. The variant feline coronaviruses that cause invariably-fatal feline infectious peritonitis (FIP) arise by sporadic mutation of an ubiquitous and only mildly pathogenic feline enteric coronavirus (FECV); a finding that has substantial management implications for cat breeders and veterinarians. Conversely, canine enteric coronavirus (CECV) shows considerable genetic and antigenic diversity but causes only mild, self-limiting diarrhoea in puppies. Routine vaccination against this virus is not recommended. Although parvoviruses, coronaviruses and retroviruses are the most important known viral causes of canine and feline gastrointestinal disease, other viruses play a role. Feline and canine rotaviruses have combined with human rotaviruses to produce new, reassortant, zoonotic viruses. Some companion animal rotaviruses can infect humans directly. Undoubtedly, further viral causes of canine and feline gastrointestinal disease await discovery.

Expression of feline interferon-alpha subtypes in Esherichia coli, and their antiviral activity and animal species specificity

Two kinds of FeIFN-alpha consisting of 166 amino acids (aa) and 171 aa were expressed in Escherichia coli, and the purified proteins were tested for antiviral activity on homologous and heterologous animal cells. Crude FeIFN induced in feline cells revealed antiviral activity on both homologous and heterologous animal cells. In contrast, both types of recombinant FeIFN-alpha revealed antiviral activity only on the feline cells. All of the FeIFN-alpha subtypes showed high activity to vesicular stomatitis virus, and the three species of feline viruses belonging to different families.

The biological effects of five feline IFN-alpha subtypes

IFN-alpha has been shown to induce both antiviral and antiproliferative activities in animals. This report describes the biological activity of five recently identified feline IFN-alpha subtypes expressed in the Chinese hamster ovary (CHO) cell line (rfeIFN-alpha1[CHO], rfeIFN-alpha2[CHO], rfeIFN-alpha3[CHO], rfeIFN-alpha5[CHO] and rfeIFN-alpha6[CHO]) and the feIFN-alpha6 subtype expressed in and purified from Pichia pastoris (rfeIFN-alpha6[P. pastoris]). The rfeIFN-alpha[CHO] subtypes were tested for antiviral activity against either Vesicular stomatitis virus (VSV) or feline calicivirus (FCV) infected feline embryonic fibroblast cell line (AH927) or Crandell feline kidney cell line (CRFK). Antiviral activity was induced against both VSV and FCV infected AH927 cells and VSV infected CRFK cells by all five of the rfeIFN-alpha[CHO] subtypes and rfeIFN-alpha6[P. pastoris]. In addition, the IFN-alpha inducible Mx gene (associated with antiviral activity) was upregulated in vivo 24 h following treatment with rfeIFN-alpha6[P. pastoris], compared to baseline levels seen prior to treatment. All of the rfeIFN-alpha[CHO] subtypes and rfeIFN-alpha6[P. pastoris] exhibited antiproliferative activity in the FeT-J cell line (an IL-2 independent feline T-cell line). Both necrosis and apoptosis were observed in rfeIFN-alpha6[P. pastoris]-treated FeT-J cells. The rfeIFN-alpha3[CHO] subtype consistently exhibited lower antiviral and antiproliferative activity compared to that observed with the other four rfeIFN-alpha[CHO] subtypes. In summary, this paper demonstrates that five previously described feIFN-alpha subtypes induce both antiviral and antiproliferative activities in vitro and are capable of upregulating the feMx gene in vivo.

Use of recombinant feline interferon and glucocorticoid in the treatment of feline infectious peritonitis

A total of 12 clinically ill cats previously diagnosed as feline infectious peritonitis (FIP) were treated with a combination of recombinant feline interferon and glucocorticoid. A complete remission (over 2 years) and a partial remission (2 to 5 months) were observed in four (33.3%) and four (33.3%) cases, respectively. Those that survived for more than 2 years were all older cats (6 to 16 years old) with the effusive form of FIP.

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.

Treatment of canine parvoviral enteritis with interferon-omega in a placebo-controlled field trial

The clinical efficacy of a recombinant feline interferon (IFN) (type omega) was evaluated under field conditions for the treatment of dogs with parvoviral enteritis. In this multicentric, double-blind, placebo-controlled trial, 94 dogs from one to 28 months old were randomly assigned to two groups which were treated intravenously either with IFN (2.5 million units/kg) or placebo once a day for three consecutive days, and monitored for clinical signs and mortality for 10 days. Each dog received individual supportive treatment The data from 92 interpretable cases (43 IFN-treated and 49 placebo) showed that the clinical signs of the IFN-treated animals improved significantly in comparison with the control animals, and that there were only three deaths in the IFN group compared with 14 deaths in the placebo group (P = 0.0096) corresponding to a 4.4-fold reduction. Alternative analyses of the data taking into account the prior vaccination status of the dogs against canine parvovirus suggested that the IFN therapy resulted in a 6.4-fold reduction in mortality (P = 0.044) in the unvaccinated cohort, a significant reduction when compared with the vaccinated cohort.