Biology subjects

Hartman, A. L.

Publications and source records attributed to Hartman, A. L..

12 recordsLinked to original sources

bioRxiv2026

Oropouche virus causes acute hepatitis in mice controlled by Type I interferons

Oropouche virus (OROV), a member of the Peribunyaviridae family endemic to South America, is a current public health threat. The recent OROV outbreak driven by a novel reassortant has caused a dramatic increase in cases in 2024 (13,785 in Brazil, versus only 261 from 2015-2022) with sustained levels of transmission in 2025. Previously underreported outcomes have been recognized including miscarriage, microcephaly, encephalitis, and death. OROV lethality in humans has been attributed to severe coagulopathy with liver involvement, and epidemiological data suggests acute hepatitis occurs in mild cases of Oropouche fever, highlighting the underrecognized role of the liver in OROV pathogenesis. We present two discrete mouse models of OROV hepatic disease -- a lethal model that recapitulates the severe coagulopathy seen in fatal human cases and a model of self-resolving acute hepatitis which recapitulates mild human disease. OROV causes focal hepatic necrosis in mice, which progresses to massive necrosis and death when the Type I interferon receptor is antagonized. Additionally, we found a contemporary OROV isolate is less pathogenic in mice than a historic prototypical strain. These studies enhance our understanding of OROV pathogenesis and pave the way for potential therapeutic development and evaluation. ImportanceThe disease burden of Oropouche fever has been underrecognized and underreported, as highlighted by the increased testing seen in the ongoing outbreak. Specifically, the role of the liver in Oropouche virus pathogenesis has been neglected. Given the ongoing outbreak and increase in severe disease manifestations, there is a present need to understand Oropouche virus pathogenesis and test potential therapeutics. The mouse models of Oropouche-induced hepatitis presented here provide a means to understand how Oropouche virus causes liver damage in both a lethal and sublethal context. These models will be useful for the preclinical evaluation of vaccines and therapeutic treatments. Additionally, we compare the pathogenicity of a historical Oropouche virus isolate to a contemporary human isolate in a lethal mouse model. This represents an additional step towards understanding whether the circulating Oropouche virus isolates are uniquely more pathogenic or if increased testing has highlighted previously unreported outcomes.

microbiology↗

bioRxiv2024

Oropouche virus infects human placenta explants and trophoblast organoids

Clinical and epidemiologic evidence from the recent outbreak of Oropouche virus (OROV) has demonstrated increased severity in clinical disease and adverse pregnancy outcomes including miscarriage, stillbirth, and neonatal demise. Serological evidence suggests vertical transmission of OROV may be responsible. OROV has not been studied in the context of pregnancy and has unknown ability to infect the relevant tissues of the maternal-fetal interface, which have anti-viral properties; therefore, the mechanisms of vertical transmission are unknown. We used polarized human trophoblast stem cell organoids and human placenta explants to demonstrate that OROV (BeAn19991) infects and replicates in human tissues of the maternal-fetal interface including chorionic villi and the microbial-resistant cell, syncytiotrophoblast. Viral replication is robust within the first 24 hours post infection, and tissues from earlier gestations may be more susceptible to infection. These data indicate tissues at the maternal-fetal interface are susceptible to OROV infection and may facilitate vertical transmission, leading to adverse pregnancy outcomes.

microbiology↗

bioRxiv2024

Lrp1 facilitates infection of neurons by Jamestown Canyon virus

Jamestown Canyon virus (JCV) is a bunyavirus and arbovirus responsible for neuroinvasive disease in the United States. Little is known about JCV pathogenesis, and no host factors required for cellular infection have been identified. Recently, we identified low-density lipoprotein receptor related protein 1 (Lrp1) as a host entry factor for two other bunyaviruses Rift Valley fever virus (RVFV) and Oropouche virus (OROV). Here, we assessed the role of Lrp1 in mediating JCV cellular infection of neurons. Both neuronal and non-neuronal immortalized cell lines deficient for Lrp1 displayed reduction in infection with JCV, and early stages of infection such as binding and internalization were impacted by lack of Lrp1. In primary rat neurons, Lrp1 was highly expressed, and the neurons were highly permissive for JCV infection. Treatment of primary neurons with recombinant receptor-associated protein (RAP), a high affinity ligand for Lrp1, resulted in reduced infectivity with JCV. In addition, pretreatment of cells with RVFV Gn inhibited JCV infection, suggesting that the two viruses may share overlapping binding sites. These results provide compelling evidence that Lrp1 is an important cellular factor for efficient infection by JCV, and thus multiple bunyaviruses with varying clinical manifestations and tissue tropism are facilitated by the host cell Lrp1. Reliance of multiple bunyaviruses on Lrp1 makes it a promising target for pan-bunyaviral antivirals and therapeutics.

microbiology↗

bioRxiv2024

Characterization of neural infection by Oropouche orthobunyavirus

Oropouche fever is a re-emerging global viral threat caused by infection with Oropouche orthobunyavirus (OROV). While disease is generally self-limiting, historical and recent reports of neurologic involvement highlight the importance of understanding the neuropathogenesis of OROV. In this study, we characterize viral replication kinetics in neurons and microglia derived from immortalized, primary, and induced pluripotent stem cell-derived cells, which are all permissive to infection. We demonstrate that ex vivo rat brain slice cultures can be infected by OROV and produce antiviral cytokines and chemokines, including IL-6, TNF- and IFN-{beta}, which introduces an additional model to study viral kinetics in the central nervous system. These findings provide additional insight into OROV neuropathogenesis and in vitro modeling strategies for a newly re-emerging arbovirus.

microbiology↗

bioRxiv2024

Vaccine strains of Rift Valley fever virus exhibit attenuation at the maternal-fetal placental interface

Rift Valley fever virus (RVFV) infection causes abortions in ruminant livestock and is associated with an increased likelihood of miscarriages in women. Using sheep and human placenta explant cultures, we sought to identify tissues at the maternal-fetal interface targeted by RVFV. Sheep villi and fetal membranes were highly permissive to RVFV infection resulting in markedly higher virus titers than human cultures. Sheep cultures were most permissive to wild-type RVFV and {Delta}NSm infection, while live attenuated RVFV vaccines (LAVs; MP-12, {Delta}NSs, and {Delta}NSs/{Delta}NSm) exhibited reduced replication. The human fetal membrane restricted wild-type and LAV replication, and when infection occurred, it was prominent in the maternal-facing side. Type-I and type-III interferons were induced in human villi exposed to LAVs lacking the NSs protein. This study supports the use of sheep and human placenta explants to understand vertical transmission of RVFV in mammals and whether LAVs are attenuated at the maternal-fetal interface. TeaserVaccine strains of Rift Valley fever virus have reduced infection and replication capacity in mammalian placenta

microbiology↗

bioRxiv2022

Oropouche orthobunyavirus infection is mediated by the cellular host factor Lrp1

Oropouche orthobunyavirus (OROV; Peribunyaviridae) is a mosquito-transmitted virus that causes widespread cases of human febrile illness in South America, with occasional progression to neurologic effects. Host entry factors mediating cellular entry of OROV are undefined. Here, we show that OROV requires the host protein low density lipoprotein-related protein 1 (Lrp1) for cellular infection. Cells from evolutionarily distinct species lacking Lrp1 were less permissive to OROV infection than cells with Lrp1. Treatment of cells with either the high-affinity Lrp1 ligand receptor-associated protein (RAP) or recombinant ectodomain truncations of Lrp1 significantly reduced OROV infection. Thus, Lrp1 is an important host factor required for infection of cells by OROV. Taken together with our results showing that Lrp1 is a newly identified receptor for Rift Valley fever virus (RVFV), Lrp1 may play a broader role in cellular infection by bunyaviruses than previously appreciated.

microbiology↗

bioRxiv2022

Congenital Rift Valley fever in Sprague Dawley rats is associated with diffuse infection and pathology of the placenta

Rift Valley fever (RVF) is a disease of animals and humans associated with abortions in ruminants and, more recently, late-gestation miscarriages in African women. Here, we use a rat model of congenital RVF to identify cellular tropism, pathology, and local immune responses occurring in the placenta during vertical transmission. Infection of pregnant rats during late gestation (embryonic day 14) resulted in vertical transmission to the placenta and widespread viral infection throughout the decidua, basal zone, and labyrinth zone. Some pups delivered from infected dams appeared normal while others had gross signs of teratogenicity including fetal death. Histopathological lesions were detected in placenta from pups regardless of teratogenicity, while teratogenic pups had more widespread hemorrhage throughout multiple placenta layers. Teratogenic events were also associated with significant increases in pro-inflammatory cytokines, type I interferons, and chemokines within the placental tissue. Thus, we found that RVFV displays a high degree of tropism for all placental tissue layers, and that the degree of hemorrhage and inflammatory mediator production is highest in placenta from pups with adverse outcomes. This is the first detailed pathological study of the mechanisms of RVFV infection of placental tissue in a tractable rodent model of congenital RVF disease.

microbiology↗

bioRxiv2020

SARS-CoV-2 infection of African green monkeys results in mild respiratory disease discernible by PET/CT imaging and prolonged shedding of infectious virus from both respiratory and gastrointestinal tracts

Vaccines are urgently needed to combat the global coronavirus disease 2019 (COVID-19) pandemic, and testing of candidate vaccines in an appropriate non-human primate (NHP) model is a critical step in the process. Infection of African green monkeys (AGM) with a low passage human isolate of SARS-CoV-2 by aerosol or mucosal exposure resulted in mild clinical infection with a transient decrease in lung tidal volume. Imaging with human clinical-grade 18F-fluoro-2-deoxy-D-glucose positron emission tomography (18F-FDG PET) co-registered with computed tomography (CT) revealed pulmonary lesions at 4 days post-infection (dpi) that resolved over time. Infectious virus was shed from both respiratory and gastrointestinal (GI) tracts in all animals in a biphasic manner, first between 2-7 dpi followed by a recrudescence at 14-21 dpi. Viral RNA (vRNA) was found throughout both respiratory and gastrointestinal systems at necropsy with higher levels of vRNA found within the GI tract tissues. All animals seroconverted simultaneously for IgM and IgG, which has also been documented in human COVID-19 cases. Young AGM represent an excellent species to study mild/subclinical COVID-19 disease and have shed light on unknown aspects of long-term virus shedding. They are ideally suited for preclinical evaluation of candidate vaccines and therapeutic interventions. One Sentence SummarySubclinical infection of African green monkeys infected with SARS-CoV-2 results in prolonged shedding of infectious virus from both respiratory and gastrointestinal tracts.

microbiology↗

bioRxiv2020

SARS-CoV-2 growth, furin-cleavage-site adaptation and neutralization using serum from acutely infected, hospitalized COVID-19 patients

SARS-CoV-2, the causative agent of COVID-19, emerged at the end of 2019 and by mid-June 2020, the virus has spread to at least 215 countries, caused more than 8,000,000 confirmed infections and over 450,000 deaths, and overwhelmed healthcare systems worldwide. Like SARS-CoV, which emerged in 2002 and caused a similar disease, SARS-CoV-2 is a betacoronavirus. Both viruses use human angiotensin-converting enzyme 2 (hACE2) as a receptor to enter cells. However, the SARS-CoV-2 spike (S) glycoprotein has a novel insertion that generates a putative furin cleavage signal and this has been postulated to expand the host range. Two low passage (P) strains of SARS-CoV-2 (Wash1: P4 and Munich: P1) were cultured twice in Vero-E6 cells and characterized virologically. Sanger and MinION sequencing demonstrated significant deletions in the furin cleavage signal of Wash1: P6 and minor variants in the Munich: P3 strain. Cleavage of the S glycoprotein in SARS-CoV-2-infected Vero-E6 cell lysates was inefficient even when an intact furin cleavage signal was present. Indirect immunofluorescence demonstrated the S glycoprotein reached the cell surface. Since the S protein is a major antigenic target for the development of neutralizing antibodies we investigated the development of neutralizing antibody titers in serial serum samples obtained from COVID-19 human patients. These were comparable regardless of the presence of an intact or deleted furin cleavage signal. These studies illustrate the need to characterize virus stocks meticulously prior to performing either in vitro or in vivo pathogenesis studies.

microbiology↗

bioRxiv2020

Applications of minimally invasive multimodal telemetry for continuous monitoring of brain function and intracranial pressure in macaques with acute viral encephalitis.

Alphaviruses such as Venezuelan equine encephalitis virus (VEEV) and Eastern equine encephalitis virus (EEEV) are arboviruses that can cause severe zoonotic disease in humans. Both VEEV and EEEV are highly infectious when aerosolized and can be used as biological weapons. Vaccines and therapeutics are urgently needed, but efficacy determination requires animal models. The cynomolgus macaque (Macaca fascicularis) provides a relevant model of human disease, but questions remain whether vaccines or therapeutics can mitigate CNS infection or disease in this model. The documentation of alphavirus encephalitis in animals relies on traditional physiological biomarkers and behavioral/neurological observations by veterinary staff; quantitative measurements such as electroencephalography (EEG) and intracranial pressure (ICP) can recapitulate underlying encephalitic processes. We detail a telemetry implantation method suitable for continuous monitoring of both EEG and ICP in awake macaques, as well as methods for collection and analysis of such data. We sought to evaluate whether changes in EEG/ICP suggestive of CNS penetration by virus would be seen after aerosol exposure of naive macaques to VEEV IC INH9813 or EEEV V105 strains compared to mock-infection in a cohort of twelve adult cynomolgus macaques. Data collection ran continuously from at least four days preceding aerosol exposure and up to 50 days thereafter. EEG signals were processed into frequency spectrum bands (delta: [0.4 - 4Hz); theta: [4 - 8Hz); alpha: [8-12Hz); beta: [12-30] Hz) and assessed for viral encephalitis-associated changes against robust background circadian variation while ICP data was assessed for signal fidelity, circadian variability, and for meaningful differences during encephalitis. Results indicated differences in delta, alpha, and beta band magnitude in infected macaques, disrupted circadian rhythm, and proportional increases in ICP in response to alphavirus infection. This novel enhancement of the cynomolgus macaque model offers utility for timely determination of onset, severity, and resolution of encephalitic disease and for the evaluation of vaccine and therapeutic candidates.

immunology↗

bioRxiv2019

A vibrating mesh nebulizer as an alternative to the Collison 3-jet nebulizer for infectious disease aerobiology.

Experimental infection of animals via inhalation containing pathogenic agents is essential to understanding the natural history and pathogenesis of infectious disease as well as evaluation of potential medical countermeasures. We evaluated whether the Aeroneb, a vibrating mesh nebulizer, would serve as an alternative to the Collison, the gold standard for generating infectious bioaerosols. While the Collison possesses desirable properties that have contributed to its longevity in infectious disease aerobiology, concerns have lingered about the volume and concentration of agent required to cause disease and the damage that jet nebulization causes to the agent. For viruses, the ratio of aerosol concentration to nebulizer concentration (spray factor, SF), the Aeroneb was superior to the Collison for four different viruses in a nonhuman primate head-only exposure chamber. Aerosol concentration of influenza was higher relative to fluorescein for the Aeroneb compared to the Collison, suggesting that the Aeroneb was less harsh to viral pathogens than the Collison when generating aerosols. The Aeroneb did not improve the aerosol SF for a vegetative bacterium, Francisella tularensis. Environmental parameters collected during the aerosols indicated that the Aeroneb generated a higher relative humidity in exposure chambers while not affecting other environmental parameters. Aerosol mass median aerodynamic diameter was generally larger and more disperse for aerosols generated by the Aeroneb than what is seen with the Collison but [≥]80% were within the range that would reach the lower respiratory tract and alveolar regions. These data suggest that for viral pathogens, the Aeroneb is a suitable alternative to the Collison 3-jet nebulizer.\n\nImportanceThe threat of aerosolization is often not the natural method of transmission. While selection of an appropriate animal model is vital for these types of experiments, other confounding factors can be controlled through a thorough understanding of experimental design and the effects that different parameters can have on disease outcome. Route of administration, particle size, and dose are all factors which can affect disease progression and need to be controlled. Aerosol research methods and equipment need to be well characterized to optimize the development of animal models for bioterrorism agents.

microbiology↗

bioRxiv2018

Rift Valley fever virus induces fetal demise through direct placental infection

Rift Valley fever virus (RVFV) infections in pregnant livestock are associated with high rates of fetal demise and have been linked to miscarriage in pregnant women. To address how acute RVFV infection during pregnancy causes detrimental effects on the fetus, we developed an immunocompetent pregnant rodent model of RVFV infection. We found that pregnant rats were more susceptible to RVFV-induced death than their non-pregnant counterparts and that RVFV infection resulted in intrauterine fetal death and severe congenital abnormalities, even in pups from infected asymptomatic pregnant rats. Virus distribution in infected dams was widespread, with a previously unrecognized preference for infection, replication, and tissue damage in the placenta. In human mid-gestation placental tissue, RVFV directly infected placental chorionic villi, with replication detected in the outermost syncytial layer. Our work identifies direct placental infection by RVFV as a mechanism for vertical transmission and points to the teratogenic potential of this virus in humans. This is the first time vertical transmission of RVFV has been shown in species other than livestock. This study highlights the potential impact of a future epidemic of this emerging mosquito-borne virus.

microbiology↗