Dengue Virus Immunity Increases Zika Virus-Induced Damage during Pregnancy.

Zika virus (ZIKV) has recently been associated with birth defects and pregnancy loss after maternal infection. Because dengue virus (DENV) and ZIKV co-circulate, understanding the role of antibody-dependent enhancement in the context of pregnancy is critical. Here, we showed that the presence of DENV-specific antibodies in ZIKV-infected pregnant mice significantly increased placental damage, fetal growth restriction, and fetal resorption. This was associated with enhanced viral replication in the placenta that coincided with an increased frequency of infected trophoblasts. ZIKV-infected human placental tissues also showed increased replication in the presence of DENV antibodies, which was reversed by FcγR blocking antibodies. Furthermore, ZIKV-mediated fetal pathogenesis was enhanced in mice in the presence of a DENV-reactive monoclonal antibody, but not in the presence of the LALA variant, indicating a dependence on FcγR engagement. Our data suggest a possible mechanism for the recent increase in severe pregnancy outcomes after ZIKV infection in DENV-endemic areas.

Functional Characterization and Direct Comparison of Influenza A, B, C, and D NS1 Proteins in vitro and in vivo.

Influenza viruses are important pathogens that affect multiple animal species, including humans. There are four types of influenza viruses: A, B, C, and D (IAV, IBV, ICV, and IDV, respectively). IAV and IBV are currently circulating in humans and are responsible of seasonal epidemics (IAV and IBV) and occasional pandemics (IAV). ICV is known to cause mild infections in humans and pigs, while the recently identified IDV primarily affect cattle and pigs. Influenza non-structural protein 1 (NS1) is a multifunctional protein encoded by the NS segment in all influenza types. The main function of NS1 is to counteract the host antiviral defense, including the production of interferon (IFN) and IFN-stimulated genes (ISGs), and therefore is considered an important viral pathogenic factor. Despite of homologous functions, the NS1 protein from the diverse influenza types share little amino acid sequence identity, suggesting possible differences in their mechanism(s) of action, interaction(s) with host factors, and contribution to viral replication and/or pathogenesis. In addition, although the NS1 protein of IAV, IBV and, to some extent ICV, have been previously studied, it is unclear if IDV NS1 has similar properties. Using an approach that allow us to express NS1 independently of the nuclear export protein from the viral NS segment, we have generated recombinant IAV expressing IAV, IBV, ICV, and IDV NS1 proteins. Although recombinant viruses expressing heterotypic (IBV, ICV, and IDV) NS1 proteins were able to replicate similarly in canine MDCK cells, their viral fitness was impaired in human A549 cells and they were highly attenuated in vivo. Our data suggest that despite the similarities to effectively counteract innate immune responses in vitro, the NS1 proteins of IBV, ICV, or IDV do not fully complement the functions of IAV NS1, resulting in deficient viral replication and pathogenesis in vivo.

A dual vaccine against influenza & Alzheimer's disease failed to enhance anti-ß-amyloid antibody responses in mice with pre-existing virus specific memory.

Novel dual vaccine, WSN-Aß(1-10), based on the recombinant influenza virus, expressing immunodominant B-cell epitope of ß-amyloid, simultaneously induced therapeutically potent anti-Aß and anti-influenza antibodies. In this study we showed that boosting of WSN-WT primed mice with WSN-Aß(1-10) enhances anti-viral, but fails to induce anti-Aß antibody responses. This inhibition is associated with expression of Aß(1-10) within the context of an inactivated influenza virus vaccine. These results demonstrate that the use of an inactivated influenza virus as a carrier for AD vaccine may not be applicable due to the possible inhibition of anti-Aß antibody response in individuals previously vaccinated or infected with influenza.

The immunological potency and therapeutic potential of a prototype dual vaccine against influenza and Alzheimer's disease.

BACKGROUND: Numerous pre-clinical studies and clinical trials demonstrated that induction of antibodies to the ß-amyloid peptide of 42 residues (Aß42) elicits therapeutic effects in Alzheimer's disease (AD). However, an active vaccination strategy based on full length Aß42 is currently hampered by elicitation of T cell pathological autoreactivity. We attempt to improve vaccine efficacy by creating a novel chimeric flu vaccine expressing the small immunodominant B cell epitope of Aß42. We hypothesized that in elderly people with pre-existing memory Th cells specific to influenza this dual vaccine will simultaneously boost anti-influenza immunity and induce production of therapeutically active anti-Aß antibodies. METHODS: Plasmid-based reverse genetics system was used for the rescue of recombinant influenza virus containing immunodominant B cell epitopes of Aß42 (Aß1-7/10). RESULTS: Two chimeric flu viruses expressing either 7 or 10 aa of Aß42 (flu-Aß1-7 or flu-Aß1-10) were generated and tested in mice as conventional inactivated vaccines. We demonstrated that this dual vaccine induced therapeutically potent anti-Aß antibodies and anti-influenza antibodies in mice. CONCLUSION: We suggest that this strategy might be beneficial for treatment of AD patients as well as for prevention of development of AD pathology in pre-symptomatic individuals while concurrently boosting immunity against influenza.

Maternal influenza viral infection causes schizophrenia-like alterations of 5-HT2A and mGlu2 receptors in the adult offspring.

Epidemiological studies indicate that maternal influenza viral infection increases the risk for schizophrenia in the adult offspring. The serotonin and glutamate systems are suspected in the etiology of schizophrenia, as well as in the mechanism of action of antipsychotic drugs. The effects of hallucinogens, such as psilocybin and mescaline, require the serotonin 5-HT(2A) receptor, and induce schizophrenia-like psychosis in humans. In addition, metabotropic glutamate receptor mGlu(2/3) agonists show promise as a new treatment for schizophrenia. Here, we investigated the level of expression and behavioral function of 5-HT(2A) and mGlu(2) receptors in a mouse model of maternal influenza viral infection. We show that spontaneous locomotor activity is diminished by maternal infection with the mouse-adapted influenza A/WSN/33 (H1N1) virus. The behavioral responses to hallucinogens and glutamate antipsychotics are both affected by maternal exposure to influenza virus, with increased head-twitch response to hallucinogens and diminished antipsychotic-like effect of the glutamate agonist. In frontal cortex of mice born to influenza virus-infected mothers, the 5-HT(2A) receptor is upregulated and the mGlu(2) receptor is downregulated, an alteration that may be involved in the behavioral changes observed. Additionally, we find that the cortical 5-HT(2A) receptor-dependent signaling pathways are significantly altered in the offspring of infected mothers, showing higher c-fos, egr-1, and egr-2 expression in response to the hallucinogenic drug DOI. Identifying a biochemical alteration that parallels the behavioral changes observed in a mouse model of prenatal viral infection may facilitate targeting therapies for treatment and prevention of schizophrenia.

Hemagglutinin-pseudotyped green fluorescent protein-expressing influenza viruses for the detection of influenza virus neutralizing antibodies.

Influenza virus is a highly contagious virus that causes yearly epidemics and occasional pandemics of great consequence. Influenza virus neutralizing antibodies (NAbs) are promising prophylactic and therapeutic reagents. Detection of NAbs in serum samples is critical to evaluate the prevalence and spread of new virus strains. Here we describe the development of a simple, sensitive, specific, and safe screening assay for the rapid detection of NAbs against highly pathogenic influenza viruses under biosafety level 2 (BSL-2) conditions. This assay is based on the use of influenza viruses in which the hemagglutinin (HA) gene is replaced by a gene expressing green fluorescent protein (GFP). These GFP-expressing influenza viruses replicate to high titers in HA-expressing cell lines, but in non-HA-expressing cells, their replication is restricted to a single cycle.