No description available.

BACKGROUND: Vibrio cholerae and Enterotoxigenic E. Coli (ETEC) are enteropathogens that are global causes of cholera and traveler’s diarrhea which are responsible for millions of diarrhea cases every year. ETEC and cholera are primarily found in Sub-Saharan Africa and Asia, particularly in nations with inadequate sanitation systems or little access to clean water. Infants and children are most vulnerable to these diseases, as severe infections can lead to stunting and death. The incidence of cholera and ETEC diarrhea have increased, due in part to changing weather patterns. At present, robust animal models for studies of ETEC colonization are lacking to study colonization and bottlenecks. The only licensed vaccines against cholera in endemic countries are killed whole cells, however, new live attenuated oral cholera vaccines (OCV) are in development and offer significant advantages. PanChol is a live attenuated OCV entering phase I trials. SPECIFIC AIMS: To propel studies of ETEC pathogenesis, I attempted to create a suckling mouse model of this globally important pathogen. To accomplish this goal, I constructed barcoded ETEC libraries that enabled me to determine founding population sizes along with intestinal ETEC burdens. To better understand PanChol, a new live attenuated OCV, I studied the shedding of the vaccine in the first 3 human volunteers to ingest this novel agent. METHODS: Triparental mating of donor strains MFDλpir pJMP1039 and MFDλpir pSM1 with recipient ETEC strains enabled construction of barcoded libraries. Neonatal CD-1 and C57BL/6 mice were infected with 104-107 CFU of wild-type ETEC to develop an infant mouse model. Founding population sizes of ETEC strains were compared via sequencing and STAMPR analysis while CFU burdens were determined via plating. Shedding of PanChol was done through enumeration of serial dilutions of fecal samples. Serotyping of shed PanChol was carried out using anti-Ogawa and anti-Inaba antisera. RESULTS: There were marked differences in ETEC small intestinal colonization in different mouse strains. Outbred CD-1 suckling mice only colonized with a 107 dose. In contrast, colonization of ETEC was approximately 106 CFU/small intestine at inocula sizes of 105 or greater in C57BL/6 mice. Laboratory studies using simulated bottlenecks made by serial dilutions established that the barcoded libraries accurately reflect founding population sizes up to 105 CFU. There was no difference in founding population sizes at the same inoculum size between WT ETEC and a hypervesiculation ∆mlaE mutant, though the founding population size increased with increasing input. PanChol retained the Hikojima serotype and shedding occurred in all volunteers with maximum colonization occurring 3 days post administration of 106 CFU. CONCLUSIONS: C57BL/6 P5 mice can serve as a new model to study ETEC intestinal colonization. Hypervesiculating ETEC did not produce a difference in founding population or colonization at the same input as WT ETEC strains. PanChol shows great promise as a viable OCV with shedding at 106 input and no serotype reversion.

Edwardsiella ictaluri causes enteric septicemia of catfish (ESC), a devastating disease in the channel catfish industry. Our research group has developed several E. ictaluri live attenuated vaccine (LAV) candidates (EiΔevpB, EiΔevpBΔfur, EiΔevpBΔhfq, EiΔevpBΔfurΔhfq), which were able to stimulate an immune response in vaccinated channel catfish and reduce ESC. However, innate, and adaptive immune responses in the lymphoid tissues of channel catfish to these LAVs are not known well. The overall goal of the project is to determine the role of adaptive and innate immune responses in catfish after vaccination with LAVs. Analysis of innate and adaptive immune-related gene expressions showed that the LAVs induced expression of adaptive immune-related genes in lymphoid tissues with less inflammation compared to wild type control. Also, the LAVs induced the expression of IgM in the sera of catfish.

No description available.

Seasonal influenza outbreaks are associated with morbidity and mortality in the United States. Though children are the most susceptible to influenza infection and are most likely to transmit the illness to others, many children are not vaccinated. The purpose of this study was to examine the relationship between seasonal influenza vaccination Advisory Committee on Immunization Practices (ACIP) recommendations, demographic characteristics, socioeconomic factors, and vaccine type among children over 3 consecutive flu seasons. This quantitative cross-sectional study was guided by the social ecology of health model. Secondary data from 3 consecutive flu seasons (2014-2015, 2015-2016, and 2016-2017) provided by the National Health Interview Survey was used for this study. Binary logistic regression and chi-square were used to analyze the data. A relationship between socioeconomic status, demographics (age, race, and family income) and vaccine type (live-attenuated influenza vaccine [LAIV]/inactivated influenza vaccine) was established among U.S. children; those who received LAIV were most likely to be White elementary school age children with a higher family income. Demographic and socioeconomic status was not considered influential in LAIV uptake for race, health insurance status, or family income. ACIP recommendations by age and year had the greatest impact on flu vaccine choice for this sample population. The results of this study can lead to social change by providing information for policy that can increase vaccine uptake, which can result in lower health cost and reduced illness and death rates associated with the flu, especially for those most at risk.

Après 30 années de recherche, de nombreux obstacles s'opposent encore à la conception d'un vaccin contre le SIDA. En effet, il n'existe pas de consensus sur les corrélats immunitaires de protection qu'il devra induire ni sur les mécanismes à l'origine de la progression vers le SIDA chez les individus infectés. Dans un premier temps, nous avons cherché à concevoir un virus hybride structuralement semblable au VIH-1 et capable de se répliquer exclusivement dans le cytoplasme des cellules infectées. Dans cet objectif, nous avons développé des nouveaux vecteurs bi et tri-cistroniques dérivés du poliovirus et contenant les séquences des gènes gag et/ou env du VIH-1. Nous avons montré que ces réplicons permettaient l'expression des protéines structurales du VIH-1 sous leur forme mature. Dans un second temps, nous avons mis en évidence une corrélation indiquant que, plus la composition nucléotidique (% A/T/G/C) d'un lentivirus diverge de celle de son hôte, plus la probabilité qu'il soit pathogène est élevée. Nous avons montré que l'optimisation artificielle de la composition nucléotidique de séquences d'ARN lentivirales diminuait leur capacité d'induction d'interféron (IFN-I) après transfection. Nous avons ensuite synthétisé un virus de l'immunodéficience simienne (VIS) dont la séquence a été artificiellement optimisée à la composition nucléotidique moyenne du macaque. Ce virus présente une capacité d'induction d'IFN-I in vitro réduite par rapport au VIS sauvage. Ces données indiquent pour la première fois un lien entre la composition nucléotidique du génome des lentivirus et la progression vers le SIDA. Elles suggèrent de nouvelles stratégies vaccinales d'atténuation du VIH-1. / After over thirty years of AIDS epidemic, we still need to identify immunological correlates of protection against AIDS and we do not properly understand how HIV causes AIDS in infected individuals. In order to reproduce the protective capacity of live attenuated viruses, we first aimed at generating a hybrid virus structurally similar to HIV-1 and able to replicate exclusively in the cytoplasm of infected cells. We developed new polioviral pluricistronic vectors that contain HIV-1 packaging sequences, gag gene and/or env gene. We then showed that the use of these replicons was compatible with the production of processed and mature HIV structural proteins. Secondly, we investigated the consequences of the lentivirus nucleotide composition (% A/T/G/C) bias on their pathogenicity. We found a correlation, indicating that AIDS results from infection by primate lentiviruses having the most divergent nucleotide composition compared to their hosts, whereas less divergent lentiviruses cause non-pathogenic infections. A strong type I interferon (IFN-I) response during the chronic phase of infection is a typical feature of lentiviral pathogenic infection. We showed that nucleotide optimization of lentiviral RNA sequences dramatically reduce their in vitro capacity to induce IFN-I. We synthesized a simian immunodeficiency virus (SIV), whose genome sequence was artificially optimized to the macaque average nucleotide composition. This virus showed a reduced capacity to stimulate IFN-I in vitro than wt SIV. These data indicate for the first time a link between the nucleotide composition of lentiviruses and their pathogenicity. They suggest new vaccine attenuation strategies against AIDS.

No description available.

Porcine circovirus type 2 (PCV2) is the causative agent of porcine circovirus-associated disease (PCVAD). Porcine reproductive and respiratory syndrome (PRRS) is caused by PRRS virus (PRRSV). Both PCV2 and PRRSV have caused devastating diseases in the swine industry worldwide, resulting in immense economic losses. One of the most common co-infections in the swine industry is PCV2 and PRRSV. The aim of this dissertation research is to explore different experimental approaches to develop novel vaccines against the two major pathogens affecting swine production and study the basic mechanisms that may be involved in viral pathogenesis. Two types of porcine circovirus (PCV), PCV1 and PCV2, have been identified thus far. PCV1, first identified as a contaminant of the PK-15 cell line, is non-pathogenic and has a low prevalence in swine herds. PCV2 is highly prevalent in most swine-producing countries and is associated with clinical PCVAD. The non-pathogenic PCV1 shares similar genomic organization with PCV2. Previously, it has been demonstrated that a genetically modified infectious chimeric PCV1-2a virus can tolerate up to a 27 aa insertion in the C-terminus of the ORF2 without affecting infectivity and produce a dual immune response against PCV2cap and the inserted epitope tag. Therefore, we evaluated the use of the non-pathogenic PCV1 wild-type (wt) virus and chimeric PCV1-2a vaccine virus (vs) to express four known B-cell epitopes of PRRSV. Peptide epitopes of PRRSV-VR2385, including GP2II (aa 40–51, ASPSHVGWWSFA), GP3I (aa 61–72, QAAAEAYEPGRS), GP5I (aa 35–46, SSSNLQLIYNLT), and GP5IV (aa 187–200, TPVTRVSAEQWGRP) were inserted in frame into the C-terminus of the ORF2 of PCV1wt as well as the PCV1-2avs. Four PCV1-PRRSVEPI chimeric viruses and four PCV1-2a-PRRSVEPI chimeric viruses were successfully rescued and shown to be infectious in vitro and co-expressed PCV1cap or PCV2cap with each specific PRRSV epitope. Two independent animal studies were conducted to evaluate whether the non-pathogenic PCV1 can serve as a vaccine delivery vector and whether the PCV1-2a vaccine virus can be used to develop a bivalent vaccine against both PCV2 and PRRSV. We demonstrated that three PCV1-PRRSVEPI chimeric viruses and two PCV1-2a-PRRSVEPI chimeric viruses were infectious in pigs. Importantly, we demonstrated that the PCV1-PRRSVEPI and PCV1-2a-PRRSVEPI chimeric viruses not only induced specific PCV1 or PCV2 IgG antibody but also specific anti-PRRSV epitope antibody responses as well. Regardless of the PCV backbone used, we showed that the PCV-PRRSV chimeric viruses elicited neutralizing antibodies against PRRSV-VR2385. These results provided a proof of concept for the potential use of the non-pathogenic PCV1 as a vaccine delivery system for PRRSV or other swine pathogens and the use of PCV1-2a vaccine virus to generate a bivalent vaccine against both PCV2 and PRRSV. PRRSV causes a persistent infection and immunosuppression. Immunomodulation of the host immune system is caused by modulation of numerous interleukins, such as type I interferons, tumor necrosis factor alpha (TNF-α), interleukin-1 (IL-1), interleukin-6 (IL-6), and interleukin-12 (IL-12) in infected pigs. Antigen-presenting cells (APCs) are the first line of defense, and their infection plays an important role in innate-mediated immune regulation during early immune responses. Among the APCs, pulmonary alveolar macrophages (PAMs), pulmonary interstitial macrophages (PIMs), and dendritic cells (DCs) are the main targets for PRRSV replication. The role of PRRSV-DCs interaction is not fully understood, and current research focuses on the production and regulation of interferons through DC-SIGN receptors. In this study, we evaluated the immunomodulation of MoDCs by PRRSV through interactions with the pDC-SIGN receptor, by blocking pDC-SIGN with recombinant hICAM-3-Fc or anti-pDC-SIGN mAb. Our results indicate that recombinant hICAM-3-Fc enhances mRNA expression of proinflammatory cytokines and that anti-pDC-SIGN mAb inhibits mRNA expression of TNF-α and IL-1α and enhances the expression of IL-12 induced by PRRSV in MoDCs. The results will help understand the molecular mechanisms of PRRSV pathogenesis. / Ph. D.