Publications by authors named "William D Pratt"

Article Synopsis
  • Ebola virus disease (EVD) has a case fatality rate of about 50% due to outbreaks in Africa, highlighting the need for effective countermeasures tested on nonhuman primate (NHP) models.
  • A study involving four rhesus macaques exposed to Ebola via aerosol revealed distinct disease stages: subclinical (high CO2 levels and lymphopenia), clinical (fever, viremia, and respiratory alkalosis), and decompensatory (coagulopathy, cytokine storms, liver and kidney injury), leading to shock and mortality.
  • The aerosol model showed differences in disease progression compared to intramuscular methods, including a longer subclinical phase and shorter clinical phase, which suggests that rapid identification of symptoms
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Most alphaviruses are mosquito-borne and can cause severe disease in humans and domesticated animals. In North America, eastern equine encephalitis virus (EEEV) is an important human pathogen with case fatality rates of 30-90%. Currently, there are no therapeutics or vaccines to treat and/or prevent human infection.

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Background: Ebola virus disease (EVD) supportive care strategies are largely guided by retrospective observational research. This study investigated the effect of EVD supportive care algorithms on duration of survival in a controlled nonhuman primate (NHP) model.

Methods: Fourteen rhesus macaques were challenged intramuscularly with a target dose of Ebola virus (1000 plaque-forming units; Kikwit).

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Mosquito-borne and sexual transmission of Zika virus (ZIKV), a TORCH pathogen, recently initiated a series of large epidemics throughout the Tropics. Animal models are necessary to determine transmission risk and study pathogenesis, as well screen antivirals and vaccine candidates. In this study, we modeled mosquito and sexual transmission of ZIKV in the African green monkey (AGM).

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Article Synopsis
  • The study investigated the effects of aerosolized Lassa virus on macaques, revealing symptoms similar to severe human cases, such as fever and rapid heart rate, while highlighting changes in immune responses like increased activated monocytes and lymphocytopenia.
  • Findings from the macaque model aim to assist in the development of medical countermeasures for both Lassa fever in endemic regions and broader biodefense strategies, particularly since there is currently no approved vaccine for LASV.
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  • The study focuses on developing fully human monoclonal antibodies (mAbs) to effectively treat Zaire ebolavirus, aiming to overcome challenges in creating rapid therapeutics for emerging infections.
  • Researchers used VelocImmune mice to produce specific anti-EBOV antibodies and identified three clones that were effective in neutralizing the virus and activating immune responses.
  • The combination of these three antibodies showed significant protective effects against EBOV in nonhuman primates, demonstrating the potential for future use in human trials and responses to Ebola outbreaks.*
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Ebola virus disease (EVD), caused by Ebola virus (EBOV), is a severe illness characterized by case fatality rates of up to 90%. The sporadic nature of outbreaks in resource-limited areas has hindered the ability to characterize the pathogenesis of EVD at all stages of infection but particularly early host responses. Pathogenesis is often studied in nonhuman primate (NHP) models of disease that replicate major aspects of human EVD.

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Article Synopsis
  • Unprotected sexual intercourse in areas with Zika virus can lead to infection, highlighting a significant risk factor for those traveling from such regions.* -
  • In a study, macaques were infected with Zika virus either intravaginally or intrarectally; 50% showed virus presence after vaginal infection, while 100% showed it after rectal infection.* -
  • The findings suggest that sexual transmission of Zika virus could sustain its presence in regions without mosquito transmission, potentially facilitating its spread.*
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Infections with filoviruses in humans are highly virulent, causing hemorrhagic fevers which result in up to 90% mortality. In addition to natural infections, the ability to use these viruses as bioterrorist weapons is of significant concern. Currently, there are no licensed vaccines or therapeutics available to combat these infections.

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Marburg virus causes severe and often lethal viral disease in humans, and there are currently no Food and Drug Administration (FDA) approved medical countermeasures. The sporadic occurrence of Marburg outbreaks does not allow for evaluation of countermeasures in humans, so therapeutic and vaccine candidates can only be approved through the FDA animal rule-a mechanism requiring well-characterized animal models in which efficacy would be evaluated. Here, we describe a natural history study where rhesus macaques were surgically implanted with telemetry devices and central venous catheters prior to aerosol exposure with Marburg-Angola virus, enabling continuous physiologic monitoring and blood sampling without anesthesia.

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  • Recent research on Ebola virus variants with different glycoprotein structures raises concerns about the safety and effectiveness of current clinical trial products.
  • An experiment was conducted where naïve and vaccinated macaques were exposed to either a 7U or 8U variant of the virus, revealing no differences in survival rates but notable delays in disease progression and other health metrics for naïve animals.
  • For vaccinated macaques, survival rates were similar between the two variants, indicating that while the glycoprotein variations affect disease course timing, they do not influence overall survivorship.
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Henipaviruses are implicated in severe and frequently fatal pneumonia and encephalitis in humans. There are no approved vaccines or treatments available for human use, and testing of candidates requires the use of well-characterized animal models that mimic human disease. We performed a comprehensive and statistically-powered evaluation of the African green monkey model to define parameters critical to disease progression and the extent to which they correlate with human disease.

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Article Synopsis
  • Multiple products for treating filoviral infections are being developed, and their effectiveness will be tested on nonhuman primates to meet licensing requirements.
  • There isn't a standardized method for deciding when to euthanize these primates after virus exposure, highlighting the need for objective criteria to avoid unnecessary distress and improve research validity.
  • Historical data from monkeys exposed to Ebola have been analyzed to identify clinical signs that can predict survival, which could help establish standardized practices for euthanasia in future studies.
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There are no vaccines or therapeutics currently approved for the prevention or treatment of ebolavirus infection. Previously, a replicon vaccine based on Venezuelan equine encephalitis virus (VEEV) demonstrated protective efficacy against Marburg virus in nonhuman primates. Here, we report the protective efficacy of Sudan virus (SUDV)- and Ebola virus (EBOV)-specific VEEV replicon particle (VRP) vaccines in nonhuman primates.

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Antibody therapies to prevent or limit filovirus infections have received modest interest in recent years, in part because of early negative experimental evidence. We have overcome the limitations of this approach, leveraging the use of antibody from nonhuman primates (NHPs) that survived challenge to filoviruses under controlled conditions. By using concentrated, polyclonal IgG antibody from these survivors, we treated filovirus-infected NHPs with multiple doses administered over the clinical phase of disease.

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Ebola hemorrhagic fever is an acute and often deadly disease caused by Ebola virus (EBOV). The possible intentional use of this virus against human populations has led to design of vaccines that could be incorporated into a national stockpile for biological threat reduction. We have evaluated the immunogenicity and efficacy of an EBOV vaccine candidate in which the viral surface glycoprotein is biomanufactured as a fusion to a monoclonal antibody that recognizes an epitope in glycoprotein, resulting in the production of Ebola immune complexes (EICs).

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Ebola viruses are highly pathogenic viruses that cause outbreaks of hemorrhagic fever in humans and other primates. To meet the need for a vaccine against the several types of Ebola viruses that cause human diseases, we developed a multivalent vaccine candidate (EBO7) that expresses the glycoproteins of Zaire ebolavirus (ZEBOV) and Sudan ebolavirus (SEBOV) in a single complex adenovirus-based vector (CAdVax). We evaluated our vaccine in nonhuman primates against the parenteral and aerosol routes of lethal challenge.

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Filoviruses (Ebola and Marburg viruses) are among the deadliest viruses known to mankind, with mortality rates nearing 90%. These pathogens are highly infectious through contact with infected body fluids and can be easily aerosolized. Additionally, there are currently no licensed vaccines available to prevent filovirus outbreaks.

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The Filoviruses Marburg virus and Ebola virus are among the deadliest of human pathogens, causing fulminant hemorrhagic fevers typified by overmatched specific immune responses and profuse inflammatory responses. Keys to both vaccination and treatment may reside, first, in the understanding of immune dysfunctions that parallel Filoviral disease and, second, in devising ways to redirect and restore normal immune function as well as to mitigate inflammation. Here, we describe how Filoviral infections may subvert innate immune responses through perturbances of dendritic cells and neutrophils, with particular emphasis on the downstream effects on adaptive immunity and inflammation.

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Marburg virus (MARV) and Ebola virus (EBOV), members of the viral family Filoviridae, cause fatal hemorrhagic fevers in humans and nonhuman primates. High viral burden is coincident with inadequate adaptive immune responses and robust inflammatory responses, and virus-mediated dysregulation of early host defenses has been proposed. Recently, a novel class of innate receptors called the triggering receptors expressed in myeloid cells (TREM) has been discovered and shown to play an important role in innate inflammatory responses and sepsis.

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Marburg virus (MARV) is an African filovirus that causes a deadly hemorrhagic fever in humans, with up to 90% mortality. Currently, there are no MARV vaccines or therapies approved for human use. We hypothesized that developing a vaccine that induces a de novo synthesis of MARV antigens in vivo will lead to strong induction of both a humoral and cell-mediated immune response against MARV.

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Ebola virus (EBOV) causes a severe hemorrhagic fever for which there are currently no vaccines or effective treatments. While lethal human outbreaks have so far been restricted to sub-Saharan Africa, the potential exploitation of EBOV as a biological weapon cannot be ignored. Two species of EBOV, Sudan ebolavirus (SEBOV) and Zaire ebolavirus (ZEBOV), have been responsible for all of the deadly human outbreaks resulting from this virus.

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The filoviruses Marburg virus and Ebola virus (EBOV) quickly outpace host immune responses and cause hemorrhagic fever, resulting in case fatality rates as high as 90% in humans and nearly 100% in nonhuman primates. The development of an effective therapeutic for EBOV is a daunting public health challenge and is hampered by a paucity of knowledge regarding filovirus pathogenesis. This report describes a successful strategy for interfering with EBOV infection using antisense phosphorodiamidate morpholino oligomers (PMOs).

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Cynomolgus macaques were exposed by aerosol to a virulent strain of western equine encephalitis virus (WEEV). Between 4 and 6 days after exposure, macaques had a significantly elevated temperature that lasted for 3-4 days. Clinical signs of encephalitis began as the body temperature decreased, and then they rapidly increased in severity.

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Two live, attenuated strains of Venezuelan equine encephalitis virus (VEE), IE1150K and V3526, were administered to macaques to determine if they could elicit protection against an aerosol challenge with virulent VEE virus of the IE variety (VEEV-IE). These viruses were rescued from full-length cDNA clones of 68U201 (VEEV-IE variety) and Trinidad donkey (VEEV-IA/B variety), respectively, and both have a furin cleavage site deletion mutation and a second-site resuscitating mutation. Both vaccines elicited neutralizing antibodies to viruses of the homologous variety but not to viruses of the heterologous variety.

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