Erling W. Rud

Bio: Erling W. Rud is an academic researcher from Health Canada. The author has contributed to research in topics: Simian immunodeficiency virus & Virus. The author has an hindex of 20, co-authored 44 publications receiving 2044 citations. Previous affiliations of Erling W. Rud include Jewish General Hospital & Erasmus University Rotterdam.

Early suppression of SIV replication by CD8+ nef-specific cytotoxic T cells in vaccinated macaques

Abstract: In order to develop a successful subunit vaccine against infection with the human immunodeficiency virus (HIV), protective immune effector functions must be identified. Until now, there has been only indirect evidence that HIV-specific cytotoxic T lymphocytes (CTLs) fulfill this role. Using the macaque simian immunodeficiency virus (SIV) model, the protective potential of nef-specific CTLs, stimulated by vaccination, was examined in animals challenged with a high intravenous dose of the pathogenic simian immunodeficiency virus, SIVmac251(32H)(pJ5). An inverse correlation was found between the vaccine-induced nef-specific CTL precursor frequency and virus load measured after challenge. In addition, the early decline in viraemia, observed in both vaccinated and unvaccinated control animals was associated with the development of virus-specific CTL activity and not with the presence of virus-specific neutralizing antibodies. The results imply that vaccines that stimulate strong CTL responses could protect against HIV infection.

Repair and evolution of nef in vivo modulates simian immunodeficiency virus virulence.

Abstract: Experimental evidence from the simian immunodeficiency virus (SIV) model of AIDS has shown that the nef gene is critical in the pathogenesis of AIDS. Consequently, nef is of considerable interest in both antiviral drug and vaccine development. Preliminary findings in two rhesus macaques indicated that a deletion of only 12 bp found in the overlapping nef/3' long terminal repeat (LTR) region (9501 to 9512) of the SIVmacC8 molecular clone was associated with reduced virus isolation frequency. We show that this deletion can be repaired in vivo by a sequence duplication event and that sequence evolution continues until the predicted amino acid sequence of the repair is virtually indistinguishable from that of the virulent wild type. These changes occurred concomitantly with reversion to virulence, evidenced by a high virus isolation frequency and load, decline in anti-p27 antibody, substantial reduction in the CD4/CD8 ratio, and development of opportunistic infections associated with AIDS. These findings clearly illustrate the capacity for repair of small attenuating deletions in primate lentiviruses and also strongly suggest that the region from 9501 to 9512 in the SIV nef/3' LTR region is of biological relevance. In addition, the ability of attenuated virus to revert to virulence raises fundamental questions regarding the nature of superinfection immunity.

Molecular and biological characterization of simian immunodeficiency virus macaque strain 32H proviral clones containing nef size variants.

Abstract: The proviral genome of the 32H reisolate of simian immunodeficiency of macaques (SIVmac32H) has been cloned and sequenced. Including both long terminal repeats, it is 10277 base pairs in length and contains open reading frames for all known SIV genes (gag, pol, vif, vpx, vpr, tat, rev, env and nef). This is the first report of an infectious SIVmac molecular clone which contains no premature termination codons. Three molecular clones of SIVmac32H have been constructed differing in sequence only within their last 1.2 kb. Two of the molecular clones, SIVmac32H(pJ5) and SIVmac32H (pC8), differ in the nef coding region by an in-frame deletion of four amino acids in pC8 and two conservative amino acid changes; other nucleotide changes in the 3′ LTR were not associated with known functionally critical motifs. The third clone, SIVmac32H(pB1), contains the last 1.2 kb of the SIVmac251 clone pBK28. The biological properties of virus produced after electroporation of these clones into C8166 cells has been assessed by infection of rhesus and cynomolgus macaques, time to seroconversion and by induction of cytopathic effects upon co-cultivation of infected rhesus peripheral blood lymphocytes with C8166 cells. The viruses obtained from these clones have identical growth kinetics in vitro but differ in their ability to persist in macaques. Macaques infected with pJ5 derived virus remain viraemic longer than macaques infected with pC8-derived virus. PCR analysis of circulating provirus indicates that the nef gene evolved over time in pJ5 virus-infected macaques, whereas late in infection in pC8 virus-infected macaques the nef gene remained invariant in sequence. These results support the observation that a nef deletion mutant of SIV mac239 lost its pathogenic potential and resulted in low-level viraemia when rhesus macaques were infected. Virus challenge pools for vaccine studies have been prepared for pJ5 using both human and monkey cell substrates and these stocks have been titrated both in vitro and in vivo. Virus has also been prepared from pC8 and titrated in vitro. This virus pool is being assessed as an attenuated live-virus vaccine in macaques. Since only virus originating from the SIVmac239 molecular clone is known to cause AIDS-like symptoms in rhesus macaques consistently, the SIVmac32H molecular clones should tell us more about which viral sequence features are important for the pathogenesis of AIDS.

Reagent and laboratory contamination can critically impact sequence-based microbiome analyses

Abstract: The study of microbial communities has been revolutionised in recent years by the widespread adoption of culture independent analytical techniques such as 16S rRNA gene sequencing and metagenomics. One potential confounder of these sequence-based approaches is the presence of contamination in DNA extraction kits and other laboratory reagents. In this study we demonstrate that contaminating DNA is ubiquitous in commonly used DNA extraction kits and other laboratory reagents, varies greatly in composition between different kits and kit batches, and that this contamination critically impacts results obtained from samples containing a low microbial biomass. Contamination impacts both PCR-based 16S rRNA gene surveys and shotgun metagenomics. We provide an extensive list of potential contaminating genera, and guidelines on how to mitigate the effects of contamination. These results suggest that caution should be advised when applying sequence-based techniques to the study of microbiota present in low biomass environments. Concurrent sequencing of negative control samples is strongly advised.

Dramatic rise in plasma viremia after CD8+ T cell depletion in simian immunodeficiency virus-infected macaques

Abstract: To determine the role of CD8(+) T cells in controlling simian immunodeficiency virus (SIV) replication in vivo, we examined the effect of depleting this cell population using an anti-CD8 monoclonal antibody, OKT8F. There was on average a 99.9% reduction of CD8 cells in peripheral blood in six infected Macaca mulatta treated with OKT8F. The apparent CD8 depletion started 1 h after antibody administration, and low CD8 levels were maintained until day 8. An increase in plasma viremia of one to three orders of magnitude was observed in five of the six macaques. The injection of a control antibody to an infected macaque did not induce a sustained viral load increase, nor did it significantly reduce the number of CD8(+) T cells. These results demonstrate that CD8 cells play a crucial role in suppressing SIV replication in vivo.

Antiviral pressure exerted by HIV-1-specific cytotoxic T lymphocytes (CTLs) during primary infection demonstrated by rapid selection of CTL escape virus.

Abstract: The HIV-1-specific cytotoxic T lymphocyte (CTL) response is temporally associated with the decline in viremia during primary HIV-1 infection, but definitive evidence that it is of importance in virus containment has been lacking. Here we show that in a patient whose early CTL response was focused on a highly immunodominant epitope in gp160, there was rapid elimination of the transmitted virus strain and selection for a virus population bearing amino acid changes at a single residue within this epitope, which conferred escape from recognition by epitope-specific CTL. The magnitude (> 100-fold), kinetics (30–72 days from onset of symptoms) and genetic pathways of virus escape from CTL pressure were comparable to virus escape from antiretroviral therapy, indicating the biological significance of the CTL response in vivo. One aim of HIV-1 vaccines should thus be to elicit strong CTL responses against multiple codominant viral epitopes.

Replication-incompetent adenoviral vaccine vector elicits effective anti-immunodeficiency-virus immunity.

Abstract: Recent studies of human immunodeficiency virus type 1 (HIV-1) infection in humans and of simian immunodeficiency virus (SIV) in rhesus monkeys have shown that resolution of the acute viral infection and control of the subsequent persistent infection are mediated by the antiviral cellular immune response. We comparatively assessed several vaccine vector delivery systems-three formulations of a plasmid DNA vector, the modified vaccinia Ankara (MVA) virus, and a replication incompetent adenovirus type 5 (Ad5) vector-expressing the SIV gag protein for their ability to elicit such immune responses in monkeys. The vaccines were tested either as a single modality or in combined modality regimens. Here we show that the most effective responses were elicited by a replication-incompetent Ad5 vector, used either alone or as a booster inoculation after priming with a DNA vector. After challenge with a pathogenic HIV-SIV hybrid virus (SHIV), the animals immunized with Ad5 vector exhibited the most pronounced attenuation of the virus infection. The replication-defective adenovirus is a promising vaccine vector for development of an HIV-1 vaccine.

Mucosal vaccines: the promise and the challenge

Abstract: Most infectious agents enter the body at mucosal surfaces and therefore mucosal immune responses function as a first line of defence. Protective mucosal immune responses are most effectively induced by mucosal immunization through oral, nasal, rectal or vaginal routes, but the vast majority of vaccines in use today are administered by injection. As discussed in this Review, current research is providing new insights into the function of mucosal tissues and the interplay of innate and adaptive immune responses that results in immune protection at mucosal surfaces. These advances promise to accelerate the development and testing of new mucosal vaccines against many human diseases including HIV/AIDS.