Pretreatment of rhesus monkeys with transdermal patches containing physostigmine and procyclidine: implications of the delivery system for the potential application against VX nerve agent intoxication in humans.

Physostigmine (Phs) is a reversible inhibitor of acetylcholinesterase (AChE) that penetrates the blood-brain barrier (BBB) and could be used to protect the central nervous system (CNS) against the effects of nerve agents. For prophylactic effectiveness, long, steady, and adequate inhibition of AChE activity by Phs is needed to broadly protect against the CNS effects of nerve agents. Here, we evaluated the efficacy of transdermal patches containing Phs and procyclidine (PC) as prophylactic agents. Patches (25 cm2) containing 4.4 mg Phs and 17.8 mg PC had a protective ratio of approximately 78.6-fold in rhesus monkeys challenged with VX nerve agent and given an antidote. Physiologically based pharmacokinetic model in conjunction with an indirect pharmacodynamic (PBPK/PD) was developed for Phs and scaled to rhesus monkeys. The model was able to reproduce the concentration profile and inhibitory effect on AChE of Phs in monkeys, as evidenced by correlation coefficients of 0.994 and 0.992 for 25 cm2 and 49 cm2 patches, respectively (i.e., kinetic data), and 0.989 and 0.968 for 25 cm2 and 49 cm2 patches, respectively (i.e., dynamic data). By extending the monkey PBPK/ PD model to humans, the effective human dose was predicted to be five applications of a 25 cm2 patch (i.e., 22 mg Phs), and two applications of a 49 cm2 patch (i.e., 17.4 mg Phs). Therefore, given that patch application of Phs in rhesus monkeys has a prolonged effect (namely, AChE inhibition of 19.6% for the 25 cm2 patch and 23.0% for the 49 cm2 patch) for up to 216 h, patch formulation of Phs may provide similar protection against nerve agent intoxication in humans.

A multipathogen DNA vaccine elicits protective immune responses against two class A bioterrorism agents, anthrax and botulism.

The potential use of biological agents has become a major public health concern worldwide. According to the CDC classification, Bacillus anthracis and Clostridium botulinum, the bacterial pathogens that cause anthrax and botulism, respectively, are considered to be the most dangerous potential biological agents. Currently, there is no licensed vaccine that is well suited for mass immunization in the event of an anthrax or botulism epidemic. In the present study, we developed a dual-expression system-based multipathogen DNA vaccine that encodes the PA-D4 gene of B. anthracis and the HCt gene of C. botulinum. When the multipathogen DNA vaccine was administered to mice and guinea pigs, high level antibody responses were elicited against both PA-D4 and HCt. Analysis of the serum IgG subtype implied a combined Th1/Th2 response to both antigens, but one that was Th2 skewed. In addition, immunization with the multipathogen DNA vaccine induced effective neutralizing antibody activity against both PA-D4 and HCt. Finally, the protection efficiency of the multipathogen DNA vaccine was determined by sequential challenge with 10 LD50 of B. anthracis spores and 10 LD50 of botulinum toxin, or vice versa, and the multipathogen DNA vaccine provided higher than 50% protection against lethal challenge with both high-risk biothreat agents. Our studies suggest the strategy used for this anthrax-botulinum multipathogen DNA vaccine as a prospective approach for developing emergency vaccines that can be immediately distributed on a massive scale in response to a biothreat emergency or infectious disease outbreak. Key points • A novel multipathogen DNA vaccine was constructed against anthrax and botulism. • Robust immune responses were induced following vaccination. • Suggests a potential vaccine development strategy against biothreat agents.

Experimental evidence of hepatitis A virus infection in pigs.

Hepatitis A virus (HAV) is the leading cause of acute viral hepatitis worldwide, with HAV infection being restricted to humans and nonhuman primates. In this study, HAV infection status was serologically determined in domestic pigs and experimental infections of HAV were attempted to verify HAV infectivity in pigs. Antibodies specific to HAV or HAV-like agents were detected in 3.5% of serum samples collected from pigs in swine farms. When the pigs were infected intravenously with 2 × 10(5) 50% tissue culture infectious dose (TCID50 ) of HAV, shedding of the virus in feces, viremia, and seroconversion were detected. In pigs orally infected with the same quantity of HAV, viral shedding was detected only in feces. HAV genomic RNA was detected in the liver and bile of intravenously infected pigs, but only in the bile of orally infected pigs. In further experiments, pigs were intravenously infected with 6 × 10(5) TCID50 of HAV. Shedding of HAV in feces, along with viremia and seroconversion, were confirmed in infected pigs but not in sentinel pigs. HAV genomic RNA was detected in the liver, bile, spleen, lymph node, and kidney of the infected pigs. HAV antigenomic RNA was detected in the spleen of one HAV-infected pig, suggesting HAV replication in splenic cells. Infiltration of inflammatory cells was observed in the livers of infected pigs but not in controls. This is the first experimental evidence to demonstrate that human HAV strains can infect pigs.

Analysis of cytokine production in a newly developed canine tracheal epithelial cell line infected with H3N2 canine influenza virus.

The Madin-Darby canine kidney (MDCK) cell line is typically used to analyze pathological features after canine influenza virus (CIV) infection. However, MDCK cells are not the ideal cell type, because they are kidney epithelial cells. Therefore, we generated an immortalized canine tracheal epithelial cell line, KU-CBE, to more reliably study immune responses to CIV infection in the respiratory tract. KU-CBE cells expressed the influenza virus receptor, α-2,3-sialic acid (SA), but not α-2,6-SA. KU-CBE and MDCK cells infected with H3N2 CIV demonstrated comparable virus growth kinetics. Gene expression levels of interleukin (IL)-1ß, IL-2, IL-4, IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, and interferon (IFN)-ß were estimated in both KU-CBE and MDCK cells infected with CIV by real-time reverse transcription polymerase chain reaction (qRT-PCR). Of these cytokines, IL-4, IL-10, TNF-α, and IFN-ß mRNAs were detected in both cell lines. Gene expression of IL-4, IL-10, and TNF-α was not significantly different in the two cell lines. However, MDCK cells exhibited a significantly higher level of IFN-ß mRNA than KU-CBE cells at 18 h post infection. Additionally, the protein concentrations of these four cytokines were determined by enzyme-linked immunosorbent assay (ELISA) using cell culture supernatants obtained from the two CIV-infected cell lines. MDCK cells produced significantly higher amounts of IL-4 and IFN-ß than KU-CBE cells. However, KU-CBE cells produced a significantly higher amount of TNF-α than MDCK cells. These data indicated that the newly developed canine tracheal epithelial cells exhibited different cytokine production patterns compared to MDCK cells when infected with CIV. Inflammation of the respiratory tract of dogs induced by CIV infection may be attributed to the elevated expression level of TNF-α in canine tracheal epithelial cells.

Induction of immunocastration in pre-pubertal boars immunized with recombinant gonadotropin-releasing hormone conjugated with Salmonella Typhimurium flagellin fljB.

Immunocastration is an alternative method used to replace surgical castration commonly performed in swine farms. In boars, the main effects of immunocastration are reduction of gonadotropin-releasing hormone (GnRH) and the resulting inhibition of testicular function. The aim of this study was to evaluate immunocastration efficacy in pre-pubertal boars vaccinated with a recombinant GnRH protein conjugated with Salmonella Typhimurium flagellin fljB (STF2). A total of 35 boars were assigned to three groups: the untreated group (n = 5), the surgically castrated group (n = 5), and the immunocastrated group (n = 25). Pigs in the immunocastration group were immunized with the GnRH-STF2 vaccine at pre-pubertal ages 4 and 8 weeks. All experimental pigs were kept for 26 weeks before slaughter. Anti-GnRH antibody levels of immunocastrated pigs were significantly higher than those of untreated pigs (P < 0.001). In contrast, testosterone levels of immunocastrated pigs were significantly lower than those of untreated pigs (P < 0.001). Statistical significances were not found in the body weights and backfat thicknesses of untreated vs. immunocastrated pigs. Weights of the testes and epididymides of immunocastrated pigs were significantly lower than those of untreated pigs (P < 0.001). Testicular tissues of immunocastrated pigs were severely suppressed compared with those of untreated pigs. In conclusion, immunization with the STF2-GnRH vaccine effectively induced immunocastration in pre-pubertal boars.

Toxicity and Efficacy Evaluation of Soluble Recombinant Ricin Vaccine.

BACKGROUND: Ricin, a toxin extracted from the seeds of Ricinus communis, is classified as a ribosome-inactivating protein. The A-subunit of ricin shows RNA N-glycosidase activity that cleaves ribosomal RNA (rRNA) and exhibits toxicity by inhibiting protein synthesis and inducing vascular leak syndrome. METHODS: In this study, we created a truncated version of the previously developed R51 ricin vaccine (RTA 1-194 D75C Y80C) through in silico analysis. RESULTS: The resulting R51-3 vaccine showed a more-than-six-fold increase in soluble protein expression when compared to R51, with over 85% solubility. In a pilot toxicity test, no toxicity was observed in hematological and biochemical parameters in BALB/c mice and New Zealand white rabbits following five repeated administrations of R51-3. Furthermore, R51-3 successfully protected mice and rabbits from a 20 × LD50 ricin challenge after three intramuscular injections spaced 2 weeks apart. Similarly, monkeys that received three injections of R51-3 survived a 60 µg/kg ricin challenge. CONCLUSIONS: These findings support R51-3 as a promising candidate antigen for ricin vaccine development.

Immune responses in mice vaccinated with virus-like particles composed of the GP5 and M proteins of porcine reproductive and respiratory syndrome virus.

Porcine reproductive and respiratory syndrome virus (PRRSV) induces reproductive failure in sows and respiratory problems in pigs of all ages. Live attenuated and inactivated vaccines are used on swine farms to control PRRSV. However, their protective efficacy against field strains of PRRSV remains questionable. New vaccines have been developed to improve the efficacy of these traditional vaccines. In this study, virus-like particles (VLPs) composed of the GP5 and M proteins of PRRSV were developed, and the capacity of the VLPs to elicit antigen-specific immunity was evaluated. Serum antibody titers and production of cytokines were measured in BALB/C mice immunized intramuscularly three times with different doses (0.5, 1.0, 2.0, and 4.0 µg) of the VLP vaccine. A commercial vaccine consisting of inactivated PRRSV and phosphate-buffered saline (PBS) were used as positive and negative controls, respectively. IgG titers to GP5 were significantly higher in all groups of mice vaccinated with the VLPs than in control mice. Neutralizing antibodies were only detected in mice vaccinated with 2.0 and 4.0 µg of the VLPs. Cytokine levels were determined in cell culture supernatants after in vitro stimulation of splenocytes with the VLPs for 3 days. Mice immunized with 4.0 µg of the VLPs produced a significantly higher amount of interferon-gamma (IFN-γ) than mice immunized with the commercial inactivated PRRSV vaccine and PBS. In contrast, immunization with the commercial vaccine induced higher production of IL-4 and IL-10 in mice than mice vaccinated with VLPs. These data together demonstrate the capacity of VLPs to induce both neutralizing antibodies and IFN-γ in immunized mice. The VLP vaccine developed in this study could serve as a platform for the generation of improved VLP vaccines to control PRRSV.

Identification of genetic diversity of porcine Norovirus and Sapovirus in Korea.

It is well known that Norovirus (NoV) and Sapovirus (SaV) identified in humans and pigs have heterogeneous genome sequences. In this study, a total of three strains of NoV and 37 strains of SaV were detected in 567 porcine fecal samples by RT-PCR, corresponding detection rates of 0.5 and 6.5%, respectively. Phylogenetic analyses were conducted using amino acid sequences of the partial RNA-dependent RNA polymerase (RdRp) and complete capsid proteins of both viruses to determine their genogroups. Analysis with the RdRp sequences indicated that all three NoV strains HW41, DG32, and DO35 detected in this study were classified into genogroup II (GII). A further analysis with the complete capsid sequence demonstrated that the DO35 strain belonged to subgenotype b in GII-21 (GII-21b) along with the SW918 strain. A total of 26 strains out of 27 strains that were selected from the 37 porcine SaVs were classified into genogroup III when they were analyzed with the RdRp sequences. The remaining strain (DO19) was not clustered with any of the previously classified SaV strains, thereby suggesting the advent of a new genogroup virus. Additional analyses with the amino acid sequence of the capsid and the nucleotide sequence of the RdRp and capsid junction region supported the notion that the DO19 strain belonged to a novel genogroup of SaV. To the best of our knowledge, this is the first report to describe a novel porcine SaV belonging to an unknown genogroup in Korea.

Induction of IFN-ß through TLR-3- and RIG-I-Mediated Signaling Pathways in Canine Respiratory Epithelial Cells Infected with H3N2 Canine Influenza Virus.

Canine influenza virus (CIV) induces acute respiratory disease in dogs. In this study, we aimed to determine the signaling pathways leading to the induction of IFN-ß in a canine respiratory epithelial cell line (KU-CBE) infected with the H3N2 subtype of CIV. Small interfering RNAs (siRNAs) specific to pattern recognition receptors (PRRs) and transcription factors were used to block the IFN-ß induction signals in H3N2 CIV-infected KU-CBE cells. Among the PRRs, only the TLR3 and RIG-I expression levels significantly (p < 0.001) increased in CIV-infected cells. Following transfection with siRNA specific to TLR3 (siTLR3) or RIG-I (siRIG-I), the mRNA expression levels of IFN-ß significantly (p < 0.001) decreased, and the protein expression of IFN-ß also decreased in infected cells. In addition, co-transfection with both siTLR3 and siRIG-I significantly reduced IRF3 (p < 0.001) and IFN-ß (p < 0.001) mRNA levels. Moreover, the protein concentration of IFN-ß was significantly (p < 0.01) lower in cells co-transfected with both siTLR3 and siRIG-I than in cells transfected with either siTLR3 or siRIGI alone. Also, the antiviral protein MX1 was only expressed in KU-CBE cells infected with CIV or treated with IFN-ß or IFN-α. Thus, we speculate that IFN-ß further induces MX1 expression, which might suppress CIV replication. Taken together, these data indicate that TLR3 and RIG-I synergistically induce IFN-ß expression via the activation of IRF3, and the produced IFN-ß further induces the production of MX1, which would suppress CIV replication in CIV-infected cells.

Analysis of complete genome sequences of swine hepatitis E virus and possible risk factors for transmission of HEV to humans in Korea.

The hepatitis E virus (HEV) is an emerging zoonotic agent, for which pigs are the most important reservoir. Complete genome sequences of two swine HEV strains, designated swKOR-1 and swKOR-2, were determined via RT-PCR and RACE-PCR. The strains contained genomes composed of 7,222- and 7,221-bp excluding the poly(A) tails, respectively. The swKOR-1 and swKOR-2 strains were classified into subtype 3a of genotype 3 via phylogenetic analysis. These strains formed a distinctive cluster in the phylogenetic tree with human and swine HEVs isolated in the USA and human HEVs isolated in Japan. Anti-HEV antibodies were identified via ELISA in 8 of 99 (8.1%) cats, whereas, among 115 cattle and 213 dogs, no HEV-specific antibodies were detected. The conserved RNA-dependent RNA polymerase (RdRp) gene of HEV could be detected via RT-PCR in 8.7% of raw oysters collected from coastal regions in Korea. The HEV RNAs detected in oysters were identified as belonging to subtype 3a. The HEV RNAs in oysters most closely resembled that of the swKOR-2 strain. They also showed a close genetic relationship with the swKOR-1 strain and the swine and human HEVs isolated in the USA. This is the first report describing the detection in oysters of HEV that may have originated from genotype 3 swine HEV in Korea. Pigs and cats infected with HEV, as well as oysters contaminated with HEV, are potential risk factors for HEV transmission to humans.

Determination of fecal shedding rates and genotypes of swine hepatitis E virus (HEV) in Korea.

Hepatitis E virus (HEV) infection induces an acute hepatitis or a subclinical disease in humans. It is known that HEV is a zoonotic agent and pigs are major reservoirs of HEV. This study was conducted to determine the fecal shedding rates of HEV in various age groups of pigs and identify the genotypes of swine HEV prevailing in Korea. A total of 565 fecal samples were collected from suckling piglets, post-weaning pigs, growing pigs, and sows at 12 swine farms. RT-PCR was used to detect the presence of swine HEV in the feces. Every swine farm examined in this study had HEV-infected pigs. The fecal shedding rates of the swine HEV at individual farms were in the range of 2.1-35.4%. The overall fecal shedding rate of HEV in individual pigs was 17.5%. The HEV shedding rates of suckling piglets, post-weaning pigs, growing pigs and sows in their feces were 6.3, 16.3, 38.0 and 9.3%, respectively. When the genotypes of swine HEVs identified in this study were determined, they were all grouped into genotype 3. They were further subdivided into subtype 3a together with human and swine HEVs isolated in the U.S.A.

Hepatitis E virus infections in humans and animals.

Hepatitis E has traditionally been considered an endemic disease of developing countries. It generally spreads through contaminated water. However, seroprevalence studies have shown that hepatitis E virus (HEV) infections are not uncommon in industrialized countries. In addition, the number of autochthonous hepatitis E cases in these countries is increasing. Most HEV infections in developed countries can be traced to the ingestion of contaminated raw or undercooked pork meat or sausages. Several animal species, including pigs, are known reservoirs of HEV that transmit the virus to humans. HEVs are now recognized as an emerging zoonotic agent. In this review, we describe the general characteristics of HEVs isolated from humans and animals, the risk factors for human HEV infection, and the current status of human vaccine development.

Induction of antibody and interferon-γ production in mice immunized with virus-like particles of swine hepatitis E virus.

Virus-like particles (VLPs) composed of the truncated capsid protein of swine hepatitis E virus (HEV) were developed and immune responses of mice immunized with the VLPs were evaluated. IgG titers specific for the capsid protein of swine HEV were significantly higher for all groups of mice immunized with the VLPs than those of the negative control mice. Splenocytes from mice immunized with the VLPs also produced significantly greater quantities of interferon (IFN)-γ than interleukin (IL)-4 and IL-10. These newly developed swine HEV VLPs have the capacity to induce antigen-specific antibody and IFN-γ production in immunized mice.

Comparative measurement of cell-mediated immune responses of swine to the M and N proteins of porcine reproductive and respiratory syndrome virus.

The principal objectives of this study were to develop autologous antigen-presenting cells (APCs) and to characterize the antigen-specific T-cell responses to the M and N proteins of porcine reproductive and respiratory syndrome virus (PRRSV) by using those APCs in outbred pigs. The orf6 and orf7 genes fused with porcine granulocyte-macrophage colony-stimulating factor (GM-CSF) were cloned into the mammalian expression vector to generate two plasmid DNAs, namely, pcDNA3.1-GM-CSF-PRRSV-M and pcDNA3.1-GM-CSF-PRRSV-N. Three of six pigs in two groups were repeatedly immunized with either plasmid DNA construct, and four pigs were used as controls. The recombinant M and N proteins fused with the protein transduction domain (PTD) of the human immunodeficiency virus type 1 transactivator of transcription protein were employed to generate major histocompatibility complex-matched autologous APCs from each pig. The levels of T-cell proliferation and gamma interferon (IFN-gamma) synthesis were compared between pigs immunized with the two plasmid DNAs after stimulation of the peripheral blood mononuclear cells (PBMCs) of each pig with the autologous antigen-presenting dendritic cells and PBMCs. Higher levels of T-cell proliferation and IFN-gamma synthesis were identified in PBMCs isolated from the pigs immunized with pcDNA3.1-GM-CSF-PRRSV-M than in those isolated from the pigs immunized with pcDNA3.1-GM-CSF-PRRSV-N. By way of contrast, serum antibodies were detected only in pigs immunized with pcDNA3.1-GM-CSF-PRRSV-N. However, no T-cell response or antibody production was detected in the control pigs. These results suggest that the M protein of PRRSV is a more potent T cell-stimulating antigen than the N protein. Nevertheless, it should be emphasized that the N protein substantially induces both cellular and humoral immune responses. The newly developed protocol for generating self APCs may prove effective in further efforts to characterize additional PRRSV proteins involved in the induction of cell-mediated immunity.