Aleksandar Masic

Elastase-Dependent Live Attenuated Swine Influenza A Viruses Are Immunogenic and Confer Protection against Swine Influenza A Virus Infection in Pigs

ABSTRACT Influenza A viruses cause significant morbidity in swine, resulting in a substantial economic burden. Swine influenza virus (SIV) infection also poses important human public health concerns. Vaccination is the primary method for the prevention of influenza virus infection. Previously, we generated two elastase-dependent mutant SIVs derived from A/Sw/Saskatchewan/18789/02(H1N1): A/Sw/Sk-R345V (R345V) and A/Sw/Sk-R345A (R345A). These two viruses are highly attenuated in pigs, making them good candidates for a live-virus vaccine. In this study, the immunogenicity and the ability of these candidates to protect against SIV infection were evaluated in pigs. We report that intratracheally administrated R345V and R345A induced antigen-specific humoral and cell-mediated immunity characterized by increased production of immunoglobulin G (IgG) and IgA antibodies in the serum and in bronchoalveolar lavage fluid, high hemagglutination inhibition titers in serum, an enhanced level of lymphocyte proliferation, and higher numbers of gamma interferon-secreting cells at the site of infection. Based on the immunogenicity results, the R345V virus was further tested in a protection trial in which pigs were vaccinated twice with R345V and then challenged with homologous A/Sw/Saskatchewan/18789/02, H1N1 antigenic variant A/Sw/Indiana/1726/88 or heterologous subtypic H3N2 A/Sw/Texas/4199-2/9/98. Our data showed that two vaccinations with R345V provided pigs with complete protection from homologous H1N1 SIV infection and partial protection from heterologous subtypic H3N2 SIV infection. This protection was characterized by significantly reduced macroscopic and microscopic lung lesions, lower virus titers from the respiratory tract, and lower levels of proinflammatory cytokines. Thus, elastase-dependent SIV mutants can be used as live-virus vaccines against swine influenza in pigs.

Immunogenicity and protective efficacy of an elastase-dependent live attenuated swine influenza virus vaccine administered intranasally in pigs.

Influenza A virus is an important respiratory pathogen of swine that causes significant morbidity and economic impact on the swine industry. Vaccination is the first choice for prevention and control of influenza infections. Live attenuated influenza vaccines (LAIV) are approved for use in humans and horses and their application provides broad protective immunity, however no LAIV against swine influenza virus (SIV) exists in the market. Previously we reported that an elastase-dependent mutant SIV A/Sw/Sk-R345V (R345V) derived from A/Sw/Saskatchewan/18789/02 (H1N1) (SIV/Sk02) is highly attenuated in pigs. Two intratracheal administrations of R345V induced strong cell-mediated and humoral immune responses and provided a high degree of protection to antigenically different SIV infection in pigs. Here we evaluated the immunogenicity and the protective efficacy of R345V against SIV infection by intranasal administration, the more practical route for vaccination of pigs in the field. Our data showed that intranasally administered R345V live vaccine is capable of inducing strong antigen-specific IFN-γ response from local tracheo-bronchial lymphocytes and antibody responses in serum and respiratory mucosa after two applications. Intranasal vaccination of R345V provided pigs with complete protection not only from parental wild type virus infection, but also from homologous antigenic variant A/Sw/Indiana/1726/88 (H1N1) infection. Moreover, intranasal administration of R345V conferred partial protection from heterologous subtypic H3N2 SIV infection in pigs. Thus, R345V elastase-dependent mutant SIV can serve as a live vaccine against antigenically different swine influenza viruses in pigs.

The PI3K/Akt pathway inhibits influenza A virus-induced Bax-mediated apoptosis by negatively regulating the JNK pathway via ASK1.

It has previously been reported that influenza A virus infection activates the phosphatidylinositol 3-kinase (PI3K)/Akt pathway. In addition, it has been shown that the mutant influenza A virus PR8-SH3-mf-1, which is unable to activate the PI3K/Akt pathway, is more pro-apoptotic than the wild-type (WT) virus. However, the molecular pathways involved in regulating this process remain unknown. Here, it is reported that, although both WT and PR8-SH3-mf-1 viruses induced apoptosis, the PR8-SH3-mf-1 virus consistently showed greater potential to induce mitochondrial membrane disruption, cytochrome c release, and translocation and conformational change of Bax than the WT virus. Furthermore, the PR8-SH3-mf-1 virus was unable to phosphorylate apoptosis signal-regulating kinase 1 (ASK1) but induced higher levels of c-jun N-terminal kinase (JNK) phosphorylation than the WT virus. Blocking JNK activity could inhibit virus-induced Bax activation and apoptosis. These results reveal that, during influenza A virus infection, the PI3K/Akt pathway negatively regulates the JNK pathway via ASK1, thereby inhibiting JNK-dependent, Bax-mediated apoptosis.

Reverse genetics-generated elastase-dependent swine influenza viruses are attenuated in pigs.

Influenza A virus causes significant morbidity in swine, resulting in a substantial economic burden. Swine influenza virus (SIV) infection also poses important human public health concerns. It has been shown that conversion of the haemagglutinin (HA) cleavage site from a trypsin-sensitive motif to an elastase-sensitive motif resulted in attenuated viruses in mouse models. However, application of this attenuation approach in a natural host has not been achieved yet. Here, we report that using reverse genetics, we generated two mutant SIVs derived from strain A/SW/SK/18789/02 (H1N1). Mutant A/SW/SK-R345V carries a mutation from arginine to valine at aa 345 of HA. Similarly, mutant A/SW/SK-R345A encodes alanine instead of arginine at aa 345 of HA. Our data showed that both mutants are solely dependent on neutrophil elastase cleavage in tissue culture. These tissue culture-grown mutant SIVs showed similar growth properties in terms of plaque size and growth kinetics to the wild-type virus. In addition, SIV mutants were able to maintain their genetic information after multiple passaging on MDCK cells. Furthermore, mutant SIVs were highly attenuated in pigs. Thus, these mutants may have the potential to serve as live attenuated vaccines.

An elastase-dependent attenuated heterologous swine influenza virus protects against pandemic H1N1 2009 influenza challenge in swine

Influenza virus infections continue to cause production losses in the agricultural industry in addition to being a human public health concern. The primary method to control influenza is through vaccination. However, currently used killed influenza virus vaccines must be closely matched to the challenge virus. The ability of an elastase-dependent live attenuated influenza A virus was evaluated to protect pigs against the pandemic H1N1 2009 influenza virus. Pigs vaccinated intranasally or intratracheally with the elastase-dependent swine influenza virus (SIV) vaccine had significantly reduced macroscopic and microscopic lung lesions and lower viral loads in the lung and in nasal swabs. Thus, elastase-dependent SIV mutants can be used as live-virus vaccines against swine influenza in pigs. In addition, low levels of cross-neutralizing antibodies to H1N1 2009 were elicited prior to challenge by the swine adapted H1N1 avian strain vaccine.

Regulation of influenza A virus induced CXCL-10 gene expression requires PI3K/Akt pathway and IRF3 transcription factor.

Influenza A virus infects human airway epithelial cells, and induces the CXC chemokine gamma interferon (IFN-γ)-inducible protein CXCL-10/IP-10 production. To understand the regulation of CXCL-10, we investigated the role of PI3K/AKT pathway in regulating virus induced CXCL-10 production. Previously we have shown that wild type (WT) influenza A virus infection activates PI3K/AKT pathway, whereas PR8-SH3-mf-1 mutant virus is unable to activate this pathway. Here we report that WT influenza A virus infection induced CXCL-10 production in A549 cells. PR8-SH3-mf-1 mutant virus infection led to reduced level of CXCL-10 mRNA transcription and protein expression. To define the transcriptional regulation factors that are important in this process, we performed studies using several mutant CXCL-10 promoter-luciferase constructs. Mutation of either of four Forkhead binding sites and two NF-κB response elements in CXCL-10 promoter did not alter promoter activity induced by WT virus. However, mutation of ISRE binding site markedly reduced luciferase activity. Our data suggested that PI3K/AKT pathway contributes to influenza A virus induced CXCL-10 production. This process is involved in binding of IRF3 to the ISRE binding site in CXCL-10 promoter region.

An Eight-Segment Swine Influenza Virus Harboring H1 and H3 Hemagglutinins Is Attenuated and Protective against H1N1 and H3N2 Subtypes in Pigs

ABSTRACT Swine influenza virus (SIV) infections continue to cause production losses in the agricultural industry in addition to being a human public health concern. The primary method of controlling SIV is through vaccination. The killed SIV vaccines currently in use must be closely matched to the challenge virus, and their protective efficacy is limited. Live attenuated influenza vaccines (LAIV) provide strong, long-lived cell-mediated and humoral immunity against different influenza virus subtypes with no need for antigen matching. Here we report the generation of a new potential LAIV, an eight-segment SIV harboring two different SIV hemagglutinins (HAs), H1 and H3, in the genetic background of H1N1 SIV. This mutant SIV was generated by fusing the H3 HA ectodomain from A/Swine/Texas/4199-2/98 (H3N2) to the cytoplasmic tail, transmembrane domain, and stalk region of neuraminidase (NA) from A/Swine/Saskatchewan/18789/02 (H1N1) SIV. While this H1-H3 chimeric SIV, when propagated in vitro in the presence of exogenous neuraminidase, showed kinetics and growth properties similar to those of the parental wild-type virus, in vivo it was highly attenuated in pigs, demonstrating a great potential for serving as a dual LAIV. Furthermore, vaccination with the H1-H3 virus elicited robust immune responses, which conferred complete protection against infections with both H1 and H3 SIV subtypes in pigs.

Clinical observations and safety profile of oral herbal products, Souroubea and Platanus spp; A pilot-toxicology study in dogs.

Abstract This pilot-study evaluated the toxicity and safety profile of two herbal products Souroubea spp Botanical Blend (SSBB) and Platanus Tree Bark (PTB) after oral administration to dogs at elevated doses for 28 days. SSBB and PTB botanicals are the major active ingredients of Sin Susto™, a novel natural product for the treatment of anxiety in dogs. Three healthy female dogs were administered elevated doses of either SSBB, PTB or a placebo and then monitored for the occurrence of any systemic and local adverse events. Data from this pilot-study revealed that SSBB and PTB had no untoward effects on the health of dogs and were deemed safe which enabled the design and execution of a larger controlled target safety and toxicology study for Sin Susto™. Abstract Ova preliminarna studija procenjuje toksičnost i bezbednost dva biljna sastojka Souroubea spp Botanical Blend (SSBB) i Platanus Tree Bark (PTB) nakon oralne primene kod pasa u povišenim dozama u trajanju od 28 dana. Biljne mešavine SSBB i PTB su dva glavna aktivna sastojka u Sin Susto™, novog prirodnog proizvoda registrovanog za preventivu/smanjenje anksioznosti kod pasa. Tri zdrave ženke pasa su primale povišene doze SSBB, PTB ili placebo nakon čega je praćena pojava sistemskih ili lokalnih neželjenih efekata. Podaci iz ovog preliminarnog istraživanja su pokazali da SSBB i PTB nisu izazvali nikakve neželjene efekte kod pasa i mogu se smatrati bezbednim što je omogućilo dalje istraživanje i izvođenje kontrolisanih ispitivanja u cilju demonstriranja bezbednosti i toksičnosti preparata Sin Susto™ kod pasa.

The in Vitro and in Vivo Anti-Cancer Potential of Mycobacterium Cell Wall Fraction (MCWF) Against Canine Transitional Cell Carcinoma of the Urinary Bladder

Abstract Transitional cell carcinoma (TCC), is the most common form of urinary bladder cancer in dogs and represents 2% of all reported canine cancers. Canine TCC is usually a high-grade invasive cancer and problems associated with TCC include urinary tract obstruction and distant metastases in more than 50% of affected dogs. TCC is most commonly located in the trigone region of the bladder precluding complete surgical resection. Current treatment options for TCC in dogs include medical therapy, surgery or radiation. Mycobacterium Cell Wall Fraction (MCWF) is a biological immunomodulator derived from non-pathogenic Mycobacterium phlei. MCWF possesses a potential in multiple veterinary areas such as anticancer therapy, palliative care and treatment of infectious diseases in both small and large animals. MCWF is considered a bifunctional anti-cancer agent that induces apoptosis of cancer cells and stimulates cytokine and chemokines synthesis by cells of the immune system. Here we report the results from in vitro and in vivo studies that could suggest use of MCWF as an additional treatment option for TCC in dogs. Particularly, we demonstrated that MCWF induces a concentration dependent inhibition of proliferation of K9TCC cells which was associated with the induction of apoptosis as measured by the proteolytic activation of caspase-3 and the degradation of PARP. Furthermore, we demonstrated the safety and potential for in vivo MCWF treatment efficacy in dogs bearing stage T2 TCC by reducing clinical signs, and improving the quality of life in dogs with TCC.

Mycobacterium cell wall fraction immunostimulant (AMPLIMUNE™) efficacy in the reduction of the severity of ETEC induced diarrhea in neonatal calves

Abstract Calf diarrhea is a common disease in young animals and the primary cause of productivity and economic losses to cattle producers worldwide. According to the report from the National Animal Health Monitoring System for U.S. dairy, more than fifty percent of the deaths of un-weaned calves is attributed to severe diarrhea. Enterotoxigenic Escherichia coli (ETEC) strain K99+ remains the most common pathogen isolated from calves which are younger than three days of age. Dam vaccination and the use of antimicrobials remain the most used prophylactic and treatment options for calf diarrhea. The rise in antibiotic resistance around the world has been a major concern and new alternative therapies have been explored. Mycobacterium Cell Wall Fraction (MCWF) is a biological immunomodulator that has a potential in multiple veterinary health services such as the treatment and prevention of infectious diseases and anticancer therapy in both small and large animals. The efficacy of the MCWF in reducing the severity of neonatal calf diarrhea and its associated mortality, following challenge with ETEC K99+ was evaluated. Twenty-three calves were placed into two experimental groups. Eleven calves received a single 1 mL dose of MCWF intravenously (IV) at the onset of clinical signs of disease following challenge. Twelve non-treated, challenged calves were retained as controls. The severity and duration of diarrhea was significantly reduced in the MCWF treated group compared to untreated controls. In addition, the mortality rate in the MCWF treated group was significantly reduced to 10% while the observed mortality in the control group reached 58%. Data from the current study suggest that MCWF could be used as an alternative treatment to reduce the severity, duration and mortality of ETEC induced diarrhea in neonatal calves.