Biomedical subjects

Lisa E Hensley

Publications and source records attributed to Lisa E Hensley.

At least 19 recordsLinked to original sources

PubMed2026

Deciphering the etiology of the 2024 outbreak of undiagnosed febrile illness in Panzi, Democratic Republic of the Congo.

In late 2024, an outbreak of over 400 cases of undiagnosed febrile illness, predominantly presenting as fever and cough, was reported in Panzi Health Zone, southwestern Democratic Republic of the Congo. Here we conducted an epidemiological and laboratory investigation to determine the etiology of the outbreak. Clinical data and specimens were prospectively collected from 108 individuals, of whom 59/108 (54.6%) were female. Children aged <5 years were the most affected (47/108, 43.5%); 14/32 (43.7%) were malnourished. Oro/nasopharyngeal swabs from 96/108 individuals were PCR tested; 26 blood samples were sequenced. Plasmodium falciparum was detected in 56/108 (51.8%) individuals. Co-infections were also detected, with influenza A(H1N1)pdm09 virus in 16/56 (28.6%) and severe acute respiratory syndrome coronavirus 2 in 10/56 (17.9%) individuals. No novel pathogens were detected via metagenomics. Our findings suggest that the outbreak was primarily associated with a surge in malaria cases, with concurrent viral respiratory infections. Increasing decentralized laboratory capacity and strengthening broader health systems remain crucial for faster outbreak detection and investigation.

Disease Outbreaks↗

PubMed2006

Postexposure protection of guinea pigs against a lethal ebola virus challenge is conferred by RNA interference.

BACKGROUND: Ebola virus (EBOV) infection causes a frequently fatal hemorrhagic fever (HF) that is refractory to treatment with currently available antiviral therapeutics. RNA interference represents a powerful, naturally occurring biological strategy for the inhibition of gene expression and has demonstrated utility in the inhibition of viral replication. Here, we describe the development of a potential therapy for EBOV infection that is based on small interfering RNAs (siRNAs). METHODS: Four siRNAs targeting the polymerase (L) gene of the Zaire species of EBOV (ZEBOV) were either complexed with polyethylenimine (PEI) or formulated in stable nucleic acid-lipid particles (SNALPs). Guinea pigs were treated with these siRNAs either before or after lethal ZEBOV challenge. RESULTS: Treatment of guinea pigs with a pool of the L gene-specific siRNAs delivered by PEI polyplexes reduced plasma viremia levels and partially protected the animals from death when administered shortly before the ZEBOV challenge. Evaluation of the same pool of siRNAs delivered using SNALPs proved that this system was more efficacious, as it completely protected guinea pigs against viremia and death when administered shortly after the ZEBOV challenge. Additional experiments showed that 1 of the 4 siRNAs alone could completely protect guinea pigs from a lethal ZEBOV challenge. CONCLUSIONS: Further development of this technology has the potential to yield effective treatments for EBOV HF as well as for diseases caused by other agents that are considered to be biological threats.

Animals↗

PubMed2006

Postexposure protection against Marburg haemorrhagic fever with recombinant vesicular stomatitis virus vectors in non-human primates: an efficacy assessment.

BACKGROUND: Effective countermeasures are urgently needed to prevent and treat infections caused by highly pathogenic and biological threat agents such as Marburg virus (MARV). We aimed to test the efficacy of a replication-competent vaccine based on attenuated recombinant vesicular stomatitis virus (rVSV), as a postexposure treatment for MARV haemorrhagic fever. METHODS: We used a rhesus macaque model of MARV haemorrhagic fever that produced 100% lethality. We administered rVSV vectors expressing the MARV Musoke strain glycoprotein to five macaques 20-30 min after a high-dose lethal injection of homologous MARV. Three animals were MARV-positive controls and received non-specific rVSV vectors. We tested for viraemia, undertook analyses for haematology and serum biochemistry, and measured humoral and cellular immune responses. FINDINGS: All five rhesus monkeys that were treated with the rVSV MARV vectors as a postexposure treatment survived a high-dose lethal challenge of MARV for at least 80 days. None of these five animals developed clinical symptoms consistent with MARV haemorrhagic fever. All the control animals developed fulminant disease and succumbed to the MARV challenge by day 12. MARV disease in the controls was indicated by: high titres of MARV (10(3)-10(5) plaque-forming units per mL); development of leucocytosis with concurrent neutrophilia at end-stage disease; and possible damage to the liver, kidney, and pancreas. INTERPRETATION: Postexposure protection against MARV in non-human primates provides a paradigm for the treatment of MARV haemorrhagic fever. Indeed, these data suggest that rVSV-based filoviral vaccines might not only have potential as preventive vaccines, but also could be equally useful for postexposure treatment of filoviral infections.

Animals↗

PubMed2006

Cynomolgus macaque as an animal model for severe acute respiratory syndrome.

BACKGROUND: The emergence of severe acute respiratory syndrome (SARS) in 2002 and 2003 affected global health and caused major economic disruption. Adequate animal models are required to study the underlying pathogenesis of SARS-associated coronavirus (SARS-CoV) infection and to develop effective vaccines and therapeutics. We report the first findings of measurable clinical disease in nonhuman primates (NHPs) infected with SARS-CoV. METHODS AND FINDINGS: In order to characterize clinically relevant parameters of SARS-CoV infection in NHPs, we infected cynomolgus macaques with SARS-CoV in three groups: Group I was infected in the nares and bronchus, group II in the nares and conjunctiva, and group III intravenously. Nonhuman primates in groups I and II developed mild to moderate symptomatic illness. All NHPs demonstrated evidence of viral replication and developed neutralizing antibodies. Chest radiographs from several animals in groups I and II revealed unifocal or multifocal pneumonia that peaked between days 8 and 10 postinfection. Clinical laboratory tests were not significantly changed. Overall, inoculation by a mucosal route produced more prominent disease than did intravenous inoculation. Half of the group I animals were infected with a recombinant infectious clone SARS-CoV derived from the SARS-CoV Urbani strain. This infectious clone produced disease indistinguishable from wild-type Urbani strain. CONCLUSIONS: SARS-CoV infection of cynomolgus macaques did not reproduce the severe illness seen in the majority of adult human cases of SARS; however, our results suggest similarities to the milder syndrome of SARS-CoV infection characteristically seen in young children.

Animals↗

PubMed2006

Cross-protection against Marburg virus strains by using a live, attenuated recombinant vaccine.

Marburg virus (MARV) has been associated with sporadic episodes of hemorrhagic fever, including a recent highly publicized outbreak in Angola that produced severe disease and significant mortality in infected patients. MARV is also considered to have potential as a biological weapon. Recently, we reported the development of a promising attenuated, replication-competent vaccine against MARV based on recombinant vesicular stomatitis virus (VSV) expressing the glycoprotein of the Musoke strain of MARV (VSVDeltaG/MARVGP-Musoke). We used this vaccine to demonstrate complete protection of cynomolgus monkeys against a homologous MARV challenge. While these results are highly encouraging, an effective vaccine would need to confer protection against all relevant strains of MARV. Here, we evaluated the protective efficacy of the VSVDeltaG/MARVGP-Musoke vaccine against two heterologous MARV strains, the seemingly more pathogenic Angola strain and the more distantly related Ravn strain. In this study, seven cynomolgus monkeys were vaccinated with the VSVDeltaG/MARVGP-Musoke vector. Three of these animals were challenged with the Angola strain, three with the Ravn strain, and a single animal with the Musoke strain of MARV. Two animals served as controls and were each injected with a nonspecific VSV vector; these controls were challenged with the Angola and Ravn strains, respectively. Both controls succumbed to challenge by day 8. However, none of the specifically vaccinated animals showed any evidence of illness either from the vaccination or from the MARV challenges and all of these animals survived. These data suggest that the VSVDeltaG/MARVGP-Musoke vaccine should be sufficient to protect against all known MARV strains.

Animals↗

PubMed2005

Development of a new vaccine for the prevention of Lassa fever.

BACKGROUND: Recent importation of Lassa fever into Germany, the Netherlands, the United Kingdom, and the United States by travelers on commercial airlines from Africa underscores the public health challenge of emerging viruses. Currently, there are no licensed vaccines for Lassa fever, and no experimental vaccine has completely protected nonhuman primates against a lethal challenge. METHODS AND FINDINGS: We developed a replication-competent vaccine against Lassa virus based on attenuated recombinant vesicular stomatitis virus vectors expressing the Lassa viral glycoprotein. A single intramuscular vaccination of the Lassa vaccine elicited a protective immune response in nonhuman primates against a lethal Lassa virus challenge. Vaccine shedding was not detected in the monkeys, and none of the animals developed fever or other symptoms of illness associated with vaccination. The Lassa vaccine induced strong humoral and cellular immune responses in the four vaccinated and challenged monkeys. Despite a transient Lassa viremia in vaccinated animals 7 d after challenge, the vaccinated animals showed no evidence of clinical disease. In contrast, the two control animals developed severe symptoms including rashes, facial edema, and elevated liver enzymes, and ultimately succumbed to the Lassa infection. CONCLUSION: Our data suggest that the Lassa vaccine candidate based on recombinant vesicular stomatitis virus is safe and highly efficacious in a relevant animal model that faithfully reproduces human disease.

Animals↗

PubMed2005

Live attenuated recombinant vaccine protects nonhuman primates against Ebola and Marburg viruses.

Vaccines and therapies are urgently needed to address public health needs stemming from emerging pathogens and biological threat agents such as the filoviruses Ebola virus (EBOV) and Marburg virus (MARV). Here, we developed replication-competent vaccines against EBOV and MARV based on attenuated recombinant vesicular stomatitis virus vectors expressing either the EBOV glycoprotein or MARV glycoprotein. A single intramuscular injection of the EBOV or MARV vaccine elicited completely protective immune responses in nonhuman primates against lethal EBOV or MARV challenges. Notably, vaccine vector shedding was not detectable in the monkeys and none of the animals developed fever or other symptoms of illness associated with vaccination. The EBOV vaccine induced humoral and apparent cellular immune responses in all vaccinated monkeys, whereas the MARV vaccine induced a stronger humoral than cellular immune response. No evidence of EBOV or MARV replication was detected in any of the protected animals after challenge. Our data suggest that these vaccine candidates are safe and highly efficacious in a relevant animal model.

Animals↗

PubMed2005

The contribution of the endothelium to the development of coagulation disorders that characterize Ebola hemorrhagic fever in primates.

Recently, there have been substantial developments in the understanding of Ebola hemorrhagic fever pathogenesis, but there are still major gaps. These infections occur in underdeveloped areas of the world, and much of our knowledge of naturally occurring disease is derived from sporadic outbreaks that occurred decades in the past. Recently conducted laboratory animal studies have provided insight into Ebola pathogenesis and may help guide clinical investigations of disease using contemporary methodologies that were not available previously. A better understanding of the relevant host and viral factors that influence clinical and virologic outcome will be critical to our ability to combat this aggressive pathogen. This article reviews the most relevant information relating to the postulated pathogenesis of this disease, focusing on the role of the endothelium in contributing to the coagulation disorders that characterize Ebola hemorrhagic fever in primates. Some of the remaining and key unanswered questions relating to the role of the vascular system in the pathogenesis of this disease, that need to be addressed in further research, are highlighted.

Animals↗

PubMed2005

Countermeasures to the bioterrorist threat of smallpox.

Variola, the agent of smallpox, is a bioterrorist threat, as is monkeypox virus, which also occurs naturally in Africa. Development of countermeasures, in the form of improved vaccines, antiviral drugs, and other therapeutic strategies are a high priority. Recent advances in molecular biology and in animal model development have provided fresh insight into the virulence determinants for smallpox and the pathophysiology of disease. The complex replication cycle for orthopoxviruses, and the pivotal role for viral-specific immunomodulatory proteins which contribute to escape from immunologic surveillance, provide many unique targets for therapeutic intervention. The "toxemia" of smallpox has been elucidated in part by variola-infected primate studies which revealed the central role of apoptosis and the evolution of a cytokine storm leading to hemorrhagic diathesis, resembling fulminent "black" smallpox. This suggests a potential role for therapeutic strategies developed for septic shock, in treatment of smallpox. Drugs licensed for other viruses which share molecular targets with orthopoxviruses (e.g. Cidofovir) or cancer drugs (e.g. Gleevec and other tyrosine kinase inhibitors) have immediate application for treatment of smallpox and monkeypox and provide leads for second generation drugs with higher therapeutic indices. Recent advances in identification of virulence determinants and immune evasion genes facilitate the design of alternative vaccines to replace live vaccinia strains that are unsuitable for a large proportion of individuals in a mass immunization campaign.

Animals↗

PubMed2005

Ebola and Marburg viruses: pathogenesis and development of countermeasures.

Ebola and Marburg viruses, family Filoviridae, are among the best known examples of emerging and re-emerging pathogens. Although outbreaks have been sporadic and geographically restricted to areas of Central Africa, the hemorrhagic fevers caused by these viruses are remarkably severe and are associated with high case fatality rates often exceeding 80 percent. In addition to humans, these viruses have decimated populations of wild apes in Central Africa. Currently, there are no vaccines or effective therapies available for human use. Progress in understanding the geneses of the pathophysiological changes that make filoviral infections of humans so destructive has been slow, primarily because these viruses require special containment for safe research. However, an increasing understanding of the molecular mechanisms of filoviral pathogenesis, facilitated by the development of new tools to elucidate critical regulatory elements in the viral life cycle, is providing new targets that can be exploited for therapeutic interventions. In addition, substantial progress has been made in developing recombinant vaccines against these viruses.

Animals↗

PubMed2004

The host response to smallpox: analysis of the gene expression program in peripheral blood cells in a nonhuman primate model.

Smallpox has played an unparalleled role in human history and remains a significant potential threat to public health. Despite the historical significance of this disease, we know little about the underlying pathophysiology or the virulence mechanisms of the causative agent, variola virus. To improve our understanding of variola pathogenesis and variola-host interactions, we examined the molecular and cellular features of hemorrhagic smallpox in cynomolgus macaques. We used cDNA microarrays to analyze host gene expression patterns in sequential blood samples from each of 22 infected animals. Variola infection elicited striking and temporally coordinated patterns of gene expression in peripheral blood. Of particular interest were features that appear to represent an IFN response, cell proliferation, immunoglobulin gene expression, viral dose-dependent gene expression patterns, and viral modulation of the host immune response. The virtual absence of a tumor necrosis factor alpha/NF-kappaB-activated transcriptional program in the face of an overwhelming systemic infection suggests that variola gene products may ablate this response. These results provide a detailed picture of the host transcriptional response during smallpox infection, and may help guide the development of diagnostic, therapeutic, and prophylactic strategies.

Animals↗

PubMed2004

Exploring the potential of variola virus infection of cynomolgus macaques as a model for human smallpox.

Smallpox virus (variola) poses a significant threat as an agent of bioterrorism. To mitigate this risk, antiviral drugs and an improved vaccine are urgently needed. Satisfactory demonstration of protective efficacy against authentic variola will require development of an animal model in which variola produces a disease course with features consistent with human smallpox. Toward this end, cynomolgus macaques were exposed to several variola strains through aerosol and/or i.v. routes. Two strains, Harper and India 7124, produced uniform acute lethality when inoculated i.v. in high doses (10(9) plaque-forming units). Lower doses resulted in less fulminant, systemic disease and lower mortality. Animals that died had profound leukocytosis, thrombocytopenia, and elevated serum creatinine levels. After inoculation, variola was disseminated by means of a monocytic cell-associated viremia. Distribution of viral antigens by immunohistochemistry correlated with the presence of replicating viral particles demonstrated by electron microscopy and pathology in the lymphoid tissues, skin, oral mucosa, gastrointestinal tract, reproductive system, and liver. These particles resembled those seen in human smallpox. High viral burdens in target tissues were associated with organ dysfunction and multisystem failure. Evidence of coagulation cascade activation (D dimers) corroborated histologic evidence of hemorrhagic diathesis. Depletion of T cell-dependent areas of lymphoid tissues occurred, probably as a consequence of bystander apoptotic mechanisms initiated by infected macrophages. Elaboration of cytokines, including IL-6 and IFN-gamma, contribute to a cytokine storm formerly known as "toxemia." A more precise understanding of disease pathogenesis should provide targets for therapeutic intervention, to be used alone or in combination with inhibitors of variola virus replication.

Animals↗

PubMed2004

Ebola virus: new insights into disease aetiopathology and possible therapeutic interventions.

Ebola virus (EBOV) gained public notoriety in the last decade largely as a consequence of the highly publicized isolation of a new EBOV species in a suburb of Washington, DC, in 1989, together with the dramatic clinical presentation of EBOV infection and high case-fatality rate in Africa (near 90% in some outbreaks), and the unusual and striking morphology of the virus. Furthermore, there are no vaccines or effective therapies currently available. Progress in understanding the origins of the pathophysiological changes that make EBOV infections of humans so devastating has been slow, primarily because these viruses require special containment for safe research. However, an increasing understanding of the mechanisms of EBOV pathogenesis, facilitated by the development of new tools to elucidate critical regulatory elements in the viral life cycle, is providing new targets that can be exploited for therapeutic interventions. Notably, identifying factors triggering the haemorrhagic complications that characterise EBOV infections led to the development of a strategy to modulate coagulopathy; this therapeutic modality successfully mitigated the effects of EBOV haemorrhagic fever in nonhuman primates. This review summarises our current understanding of EBOV pathogenesis and discusses various approaches to therapeutic intervention based on our current understanding of how EBOV produces a lethal infection.

Animals↗

PubMed2004

Depletion of peripheral blood T lymphocytes and NK cells during the course of ebola hemorrhagic Fever in cynomolgus macaques.

During the course of an experimentally induced Ebola virus (EBOVA) infection of cynomolgus macaques, peripheral blood mononuclear cells were isolated and characterized by multi-color flow cytometry. Both CD4+ and CD8+ lymphocyte counts decreased 60-70% during the first 4 days after infection. Among CD8+ lymphocytes, this decline was greatest among the CD8(lo) population, which was composed mostly of CD3- CD16+ NK cells. In contrast, the number of CD20+ B lymphocytes in the blood did not significantly change during the course of the infection. Phenotypic analysis of T lymphocyte subsets by flow cytometry failed to show evidence of a robust immune response to the infection. Apoptosis could be detected as early as day 2 postinfection among the CD8+ and CD16+ subsets of lymphocytes. Increased expression of CD95 (Fas) suggests that apoptosis may be induced via signaling through the Fas/Fas-L cascade. In contrast, the number of HLA-DR+ cells increased tenfold in the blood during the course of infection. These data suggest that EBOV may block dendritic cell maturation after infection, thereby inhibiting activation of lymphocytes and eliminating those subsets that are most likely to be capable of mounting an effective response to the virus.

Animals↗

PubMed2004

Interferon-beta 1a and SARS coronavirus replication.

A global outbreak of severe acute respiratory syndrome (SARS) caused by a novel coronavirus began in March 2003. The rapid emergence of SARS and the substantial illness and death it caused have made it a critical public health issue. Because no effective treatments are available, an intensive effort is under way to identify and test promising antiviral drugs. Here, we report that recombinant human interferon-beta 1a potently inhibits SARS coronavirus replication in vitro.

Animals↗

PubMed2003

Treatment of Ebola virus infection with a recombinant inhibitor of factor VIIa/tissue factor: a study in rhesus monkeys.

BACKGROUND: Infection with the Ebola virus induces overexpression of the procoagulant tissue factor in primate monocytes and macrophages, suggesting that inhibition of the tissue-factor pathway could ameliorate the effects of Ebola haemorrhagic fever. Here, we tested the notion that blockade of fVIIa/tissue factor is beneficial after infection with Ebola virus. METHODS: We used a rhesus macaque model of Ebola haemorrhagic fever, which produces near 100% mortality. We administered recombinant nematode anticoagulant protein c2 (rNAPc2), a potent inhibitor of tissue factor-initiated blood coagulation, to the macaques either 10 min (n=6) or 24 h (n=3) after a high-dose lethal injection of Ebola virus. Three animals served as untreated Ebola virus-positive controls. Historical controls were also used in some analyses. FINDINGS: Both treatment regimens prolonged survival time, with a 33% survival rate in each treatment group. Survivors are still alive and healthy after 9 months. All but one of the 17 controls died. The mean survival for the six rNAPc2-treated macaques that died was 11.7 days compared with 8.3 days for untreated controls (p=0.0184). rNAPc2 attenuated the coagulation response as evidenced by modulation of various important coagulation factors, including plasma D dimers, which were reduced in nearly all treated animals; less prominent fibrin deposits and intravascular thromboemboli were observed in tissues of some animals that succumbed to Ebola virus. Furthermore, rNAPc2 attenuated the proinflammatory response with lower plasma concentrations of interleukin 6 and monocyte chemoattractant protein-1 (MCP-1) noted in the treated than in the untreated macaques. INTERPRETATION: Post-exposure protection with rNAPc2 against Ebola virus in primates provides a new foundation for therapeutic regimens that target the disease process rather than viral replication.

Animals↗

PubMed2003

Mechanisms underlying coagulation abnormalities in ebola hemorrhagic fever: overexpression of tissue factor in primate monocytes/macrophages is a key event.

Disseminated intravascular coagulation is a prominent manifestation of Ebola virus (EBOV) infection. Here, we report that tissue factor (TF) plays an important role in triggering the hemorrhagic complications that characterize EBOV infections. Analysis of samples obtained from 25 macaques showed increased levels of TF associated with lymphoid macrophages, whereas analysis of peripheral blood-cell RNA showed increased levels of TF transcripts by day 3. Plasma from macaques contained increased numbers of TF-expressing membrane microparticles. Dysregulation of the fibrinolytic system developed during the course of infection, including a rapid decrease in plasma levels of protein C. Infection of primary human monocytes/macrophages (PHMs) was used to further evaluate the role of TF in EBOV infections. Analysis of PHM RNA at 1-48 h showed increased TF transcripts, whereas levels of TF protein were dramatically increased by day 2. Thus, chemotherapeutic strategies aimed at controlling overexpression of TF may ameliorate the effects of EBOV hemorrhagic fever.

Animals↗

PubMed2003

Reverse genetics with a full-length infectious cDNA of severe acute respiratory syndrome coronavirus.

A previously undescribed coronavirus (CoV) is the etiologic agent responsible for severe acute respiratory syndrome (SARS). Using a panel of contiguous cDNAs that span the entire genome, we have assembled a full-length cDNA of the SARS-CoV Urbani strain, and have rescued molecularly cloned SARS viruses (infectious clone SARS-CoV) that contained the expected marker mutations inserted into the component clones. Recombinant viruses replicated as efficiently as WT virus and both were inhibited by treatment with the cysteine proteinase inhibitor (2S,3S)-transepoxysuccinyl-L-leucylamido-3-methylbutane ethyl ester. In addition, subgenomic transcripts were initiated from the consensus sequence ACGAAC in both the WT and infectious clone SARS-CoV. Availability of a SARS-CoV full-length cDNA provides a template for manipulation of the viral genome, allowing for the rapid and rational development and testing of candidate vaccines and therapeutics against this important human pathogen.

Animals↗