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In Korea, typhoid fever is a rare disease due to improved living standards. However, typhoid fever remains a major burden in developing countries and regions, such as India and Southeast Asia. In this study, we isolated Salmonella Typhi (S. Typhi) from eight patients with typhoid fever who were travelers returning from India. The strains isolated were characterized by antimicrobial susceptibility profiling and whole-genome sequencing (WGS) analysis. All strains were resistant to nalidixic acid and azithromycin. Among them, four isolates were highly resistant to ciprofloxacin (MIC ≥32 μg/ml); these strains have not been confirmed in Korea PulseNet DB. According to WGS, the ciprofloxacin-resistant strains belong to the global dominant multidrug-resistant (MDR) haplotype H58 (SNP glpA C1047T, SptP protein Q185* (premature stop codon)) and do not harbor the MDR plasmid. H58-associated SNPs in membrane and metabolism genes, including yhdA, yajI, hyaE, tryE, rlpB and metH, are present. Additionally, phylogenetic analysis assigned the H58 strains to sublineage II, whereas the non-H58 strains are closely related to haplotype H50. The presence of high-level ciprofloxacin-resistant S. Typhi haplotype H58 in Korea was first confirmed as due to influx from overseas via travelers. This study provides information about intercontinental drug-resistant transmission between countries and suggests that travelers need to be careful about personal hygiene.

Recently identified highly pathogenic avian influenza (HPAI) H5N8 viruses (clade 2.3.4.4) are relatively low to moderately pathogenic in mammalian hosts compared with HPAI H5N1 viruses. In this study, we generated reassortant viruses comprised of A/MD/Korea/W452/2014(H5N8) with substitution of individual genes from A/EM/Korea/W149/2006(H5N1) to understand the contribution of each viral gene to virulence in mammals. Substituting the PB2 gene segment or the NA gene segment of the H5N8 virus by that from the H5N1 virus resulted in significantly enhanced pathogenicity compared with the parental H5N8 virus in mice. Of note, substitution of the PB2 gene segment of the H5N8 virus by that from the H5N1 virus resulted in a 1000-fold increase in virulence for mice compared with the parental virus (MLD50 decreased from 105.8 to 102.5 EID50). Further, the W452W149PB2 virus also induced the highest virus titers in lungs at all time points and the highest levels of inflammatory cytokine responses among all viruses tested. This high virulence phenotype was also confirmed by high viral titers in the respiratory tracts of infected ferrets. Further, a mini-genome assay revealed that W452W149PB2 has significantly increased polymerase activity (p < 0.001). Taken together, our study demonstrates that a single gene substitution from other avian influenza viruses can alter the pathogenicity of recent H5N8 viruses, and therefore emphasizes the need for intensive monitoring of reassortment events among co-circulating avian and mammalian viruses.

Abstract The antiviral activities of synthesized Kα2-helix peptide, which was derived from the viral FLICE-like inhibitor protein (vFLIP) of Kaposi’s sarcoma-associated herpesvirus (KSHV), against influenza A virus (IAV) were investigated in vitro and in vivo, and mechanisms of action were suggested. In addition to the robust autophagy activity of the Kα2-helix peptide, the present study showed that treatment with the Kα2 peptide fused with the TAT peptide significantly inhibited IAV replication and transmission. Moreover, TAT-Kα2 peptide protected the mice, that were challenged with lethal doses of highly pathogenic influenza A H5N1 or H1N1 viruses. Mechanistically, we found that TAT-Kα2 peptide destabilized the viral membranes, depending on their lipid composition of the viral envelop. In addition to IAV, the Kα2 peptide inhibited infections with enveloped viruses, such as Vesicular Stomatitis Virus (VSV) and Respiratory Syncytial Virus (RSV), without cytotoxicity. These results suggest that TAT-Kα2 peptide is a potential antiviral agent for controlling emerging or re-emerging enveloped viruses, particularly diverse subtypes of IAVs.

Fas-associated factor 1 is a death-promoting protein that induces apoptosis by interacting with the Fas receptor. Until now, FAF1 was reported to interact potentially with diverse proteins and to function as a negative and/or positive regulator of several cellular possesses. However, the role of FAF1 in defense against bacterial infection remains unclear. Here, we show that FAF1 plays a pivotal role in activating NADPH oxidase in macrophages during Listeria monocytogenes infection. Upon infection by L. monocytogenes, FAF1 interacts with p67phox (an activator of the NADPH oxidase complex), thereby facilitating its stabilization and increasing the activity of NADPH oxidase. Consequently, knockdown or ectopic expression of FAF1 had a marked effect on production of ROS, proinflammatory cytokines, and antibacterial activity, in macrophages upon stimulation of TLR2 or after infection with L. monocytogenes. Consistent with this, FAF1gt/gt mice, which are knocked down in FAF1, showed weaker inflammatory responses than wild-type mice; these weaker responses led to increased replication of L. monocytogenes. Collectively, these findings suggest that FAF1 positively regulates NADPH oxidase-mediated ROS production and antibacterial defenses.

Summary: Small heterodimer partner (SHP) is an orphan nuclear receptor that acts as a transcriptional co-repressor by interacting with nuclear receptors and transcription factors. Although SHP plays a negative regulatory function in various signaling pathways, its role in virus infection has not been studied. Here, we report that SHP is a potent negative regulator of the virus-mediated type I IFN signaling that maintains homeostasis within the antiviral innate immune system. Upon virus infection, SHP interacts specifically with CREB-binding protein (CBP) in the nucleus, thereby obstructing CBP/β-catenin interaction competitively. Consequently, SHP-deficient cells enhance antiviral responses, including transcription of the type I IFN gene, upon virus infection. Furthermore, SHP-deficient mice show higher levels of IFN production and are more resistant to influenza A virus infection. Our results suggest that SHP is a nuclear regulator that blocks transcription of the type I IFN gene to inhibit excessive innate immune responses. : Interferon (IFN), which has an antiviral effect, must be tightly modulated to prevent excessive induction that adversely affects the host. Kim et al. demonstrate that SHP acts as negative regulator of type I IFN signaling, which inhibits IFN gene transcription by blocking the interaction of CBP and β-catenin. Keywords: SHP, type I interferon, CBP, β-catenin

Wild ginseng has better pharmacological effects than cultivated ginseng. However, its industrialization is limited by the inability to grow wild ginseng on a large scale. Herein, we demonstrate how to optimize ginseng production through cultivation, and how to enhance the concentrations of specific ginsenosides through fermentation. In the study, we also evaluated the ability of fermented cultured wild ginseng root extract (HLJG0701-β) to inhibit acetylcholinesterase (AChE), as well as its neuroprotective effects and antioxidant activity. In invitro tests, HLJG0701-β inhibited AChE activity and exerted neuroprotective and antioxidant effects (showing increased catalyst activity but decreased reactive oxygen species concentration). In invivo tests, after HLJG0701-β was orally administered at doses of 0, 125, 250, and 500 mg/kg in an animal model of memory impairment, behavioral evaluation (Morris water maze test and Y-maze task test) was performed. The levels of AChE, acetylcholine (ACh), blood catalase (CAT), and malondialdehyde (MDA) in brain tissues were measured. The results showed that HLJG0701-β produced the best results at a dose of 250 mg/kg or more. The neuroprotective mechanism of HLJG0701-β was determined to involve the inhibition of AChE activity and a decrease in oxidative stress. In summary, both invitro and invivo tests confirmed that HJG0701-β administration can lead to memory improvement.

[This corrects the article DOI: 10.1371/journal.ppat.1006398.].

Epimedium koreanum Nakai has been extensively used in traditional Korean and Chinese medicine to treat a variety of diseases. Despite the plant’s known immune modulatory potential and chemical make-up, scientific information on its antiviral properties and mode of action have not been completely investigated. In this study, the broad antiviral spectrum and mode of action of an aqueous extract from Epimedium koreanum Nakai was evaluated in vitro, and moreover, the protective effect against divergent influenza A subtypes was determined in BALB/c mice. An effective dose of Epimedium koreanum Nakai markedly reduced the replication of Influenza A Virus (PR8), Vesicular Stomatitis Virus (VSV), Herpes Simplex Virus (HSV) and Newcastle Disease Virus (NDV) in RAW264.7 and HEK293T cells. Mechanically, we found that an aqueous extract from Epimedium koreanum Nakai induced the secretion of type I IFN and pro-inflammatory cytokines and the subsequent stimulation of the antiviral state in cells. Among various components present in the extract, quercetin was confirmed to have striking antiviral properties. The oral administration of Epimedium koreanum Nakai exhibited preventive effects on BALB/c mice against lethal doses of highly pathogenic influenza A subtypes (H1N1, H5N2, H7N3 and H9N2). Therefore, an extract of Epimedium koreanum Nakai and its components play roles as immunomodulators in the innate immune response, and may be potential candidates for prophylactic or therapeutic treatments against diverse viruses in animal and humans.

FAS-associated factor-1 (FAF1) is a component of the death-inducing signaling complex involved in Fas-mediated apoptosis. It regulates NF-κB activity, ubiquitination, and proteasomal degradation. Here, we found that FAF1 positively regulates the type I interferon pathway. FAF1gt/gt mice, which deficient in FAF1, and FAF1 knockdown immune cells were highly susceptible to RNA virus infection and showed low levels of inflammatory cytokines and type I interferon (IFN) production. FAF1 was bound competitively to NLRX1 and positively regulated type I IFN signaling by interfering with the interaction between NLRX1 and MAVS, thereby freeing MAVS to bind RIG-I, which switched on the MAVS-RIG-I-mediated antiviral signaling cascade. These results highlight a critical role of FAF1 in antiviral responses against RNA virus infection.

The endemicity of highly pathogenic avian influenza (HPAI) A(H5N1) viruses in Asia has led to the generation of reassortant H5 strains with novel gene constellations. A newly emerged HPAI A(H5N8) virus caused poultry outbreaks in the Republic of Korea in 2014. Because newly emerging high-pathogenicity H5 viruses continue to pose public health risks, it is imperative that their pathobiological properties be examined. Here, we characterized A/mallard duck/Korea/W452/2014 (MDk/W452(H5N8)), a representative virus, and evaluated its pathogenic and pandemic potential in various animal models. We found that MDk/W452(H5N8), which originated from the reassortment of wild bird viruses harbored by migratory waterfowl in eastern China, replicated systemically and was lethal in chickens, but appeared to be attenuated, albeit efficiently transmitted, in ducks. Despite predominant attachment to avian-like virus receptors, MDk/W452(H5N8) also exhibited detectable human virus-like receptor binding and replicated in human respiratory tract tissues. In mice, MDk/W452(H5N8) was moderately pathogenic and had limited tissue tropism relative to previous HPAI A(H5N1) viruses. It also induced moderate nasal wash titers in inoculated ferrets; additionally, it was recovered in extrapulmonary tissues and one of three direct-contact ferrets seroconverted without shedding. Moreover, domesticated cats appeared to be more susceptible than dogs to virus infection. With their potential to become established in ducks, continued circulation of A(H5N8) viruses could alter the genetic evolution of pre-existing avian poultry strains. Overall, detailed virological investigation remains a necessity given the capacity of H5 viruses to evolve to cause human illness with few changes in the viral genome.

The authors wish to make the following change to their paper [1].[...]

We demonstrate that the novel pandemic influenza (H1N1) viruses have human virus–like receptor specificity and can no longer replicate in aquatic waterfowl, their historic natural reservoir. The biological properties of these viruses are consistent with those of their phylogenetic progenitors, indicating longstanding adaptation to mammals.

During the 2006–2007 winter season in South Korea, several outbreaks of highly pathogenic avian influenza virus (H5N1) were confirmed among domestic poultry and in migratory bird habitats. Phylogenetic analysis showed that all isolates were closely related and that all belong to the A/bar-headed goose/Qinghai/5/2005–like lineage rather than the A/chicken/Korea/ES/2003–like lineage.

In order to identify new potential antiviral agents, recent studies have advocated thorough testing of herbal medicines or natural substances that are traditionally used to prevent viral infections. Antiviral activities and the mechanism of action of the total aqueous extract preparation of KIOM-C, a novel herbal medicine, against diverse types of viruses were investigated. In vitro antiviral activity against A/Puerto Rico/8/34 (H1N1) (PR8), vesicular stomatitis virus (VSV), and Newcastle disease virus (NDV) through the induction of type-I interferon related protein phosphorylation and up-regulation of pro-inflammatory cytokines in murine macrophage cells (RAW264.7) were determined. In vivo, KIOM-C-treated BALB/c mice showed higher survivability and lower lung viral titers when challenged with A/Aquatic bird/Korea/W81/2005 (H5N2), A/PR/8/34(H1N1), A/Aquatic bird/Korea/W44/2005(H7N3) or A/Chicken/Korea/116 /2004(H9N2) influenza subtypes in contrast with the non-treated group. The present study revealed that total aqueous extract preparation of KIOM-C stimulates an antiviral state in murine macrophage cells and in mice leading to inhibition of viral infection and protection against lethal challenges.

To develop a safe and effective mucosal vaccine against pathogenic influenza viruses, we constructed recombinant Lactobacillus casei strains that express conserved matrix protein 2 with (pgsA-CTA1-sM2/L. casei) or without (pgsA-sM2/L. casei) cholera toxin subunit A1 (CTA1) on the surface. The surface localization of the fusion protein was verified by cellular fractionation analyses, flow cytometry and immunofluorescence microscopy. Oral and nasal inoculations of recombinant L. casei into mice resulted in high levels of serum immunoglobulin G (IgG) and mucosal IgA. However, the conjugation of cholera toxin subunit A1 induced more potent mucosal, humoral and cell-mediated immune responses. In a challenge test with 10 MLD50 of A/EM/Korea/W149/06(H5N1), A/Puerto Rico/8/34(H1N1), A/Aquatic bird /Korea/W81/2005(H5N2), A/Aquatic bird/Korea/W44/2005(H7N3), and A/Chicken/Korea/116/2004(H9N2) viruses, the recombinant pgsA-CTA1-sM2/L. casei provided better protection against lethal challenges than pgsA-sM2/L. casei, pgsA/L. casei and PBS in mice. These results indicate that mucosal immunization with recombinant L. casei expressing CTA1-conjugated sM2 protein on its surface is an effective means of eliciting protective immune responses against diverse influenza subtypes.

The current pandemic (H1N1) 2009 virus remains transmissible among humans worldwide with cases of reverse zoonosis, providing opportunities to produce more pathogenic variants which could pose greater human health concerns. To investigate whether recent seasonal human or swine H1N1 vaccines could induce cross-reactive immune responses against infection with the pandemic (H1N1) 2009 virus, mice, ferrets or mini-pigs were administered with various regimens (once or twice) and antigen content (1.77, 3.5 or 7.5 microg HA) of a-Brsibane/59/07, a-CAN01/04 or RgCA/04/09xPR8 vaccine. Receipt of a-CAN01/04 (2-doses) but not a-Brisbane/59/07 induced detectable but modest (20-40 units) cross-reactive serum antibody against CA/04/09 by hemagglutinin inhibition (HI) assays in mice. Only double administration (7.5 microg HA) of both vaccine in ferrets could elicit cross-reactivity (30-60 HI titers). Similar antigen content of a-CAN01/04 in mini-pigs also caused a modest approximately 30 HI titers (twice vaccinated). However, vaccine-induced antibody titers could not suppress active virus replication in the lungs (mice) or virus shedding (ferrets and pigs) of immunized hosts intranasally challenged with CA/04/09. Furthermore, neither ferrets nor swine could abrogate aerosol transmission of the virus into naïve contact animals. Altogether, these results suggest that neither recent human nor animal H1N1 vaccine could provide complete protectivity in all animal models. Thus, this study warrants the need for strain-specific vaccines that could yield the optimal protection desired for humans and/or animals.