Sialic Acid Receptor Specificity in Mammary Gland of Dairy Cattle Infected with Highly Pathogenic Avian Influenza A(H5N1) Virus.

In March 2024, the US Department of Agriculture's Animal and Plant Health Inspection Service reported detection of highly pathogenic avian influenza (HPAI) A(H5N1) virus in dairy cattle in the United States for the first time. One factor that determines susceptibility to HPAI H5N1 infection is the presence of specific virus receptors on host cells; however, little is known about the distribution of the sialic acid (SA) receptors in dairy cattle, particularly in mammary glands. We compared the distribution of SA receptors in the respiratory tract and mammary gland of dairy cattle naturally infected with HPAI H5N1. The respiratory and mammary glands of HPAI H5N1-infected dairy cattle are rich in SA, particularly avian influenza virus-specific SA α2,3-gal. Mammary gland tissues co-stained with sialic acids and influenza A virus nucleoprotein showed predominant co-localization with the virus and SA α2,3-gal. HPAI H5N1 exhibited epitheliotropism within the mammary gland, and we observed rare immunolabeling within macrophages.

Smallpox lesion characterization in placebo-treated and tecovirimat-treated macaques using traditional and novel methods.

Smallpox was the most rampant infectious disease killer of the 20th century, yet much remains unknown about the pathogenesis of the variola virus. Using archived tissue from a study conducted at the Centers for Disease Control and Prevention we characterized pathology in 18 cynomolgus macaques intravenously infected with the Harper strain of variola virus. Six macaques were placebo-treated controls, six were tecovirimat-treated beginning at 2 days post-infection, and six were tecovirimat-treated beginning at 4 days post-infection. All macaques were treated daily until day 17. Archived tissues were interrogated using immunohistochemistry, in situ hybridization, immunofluorescence, and electron microscopy. Gross lesions in three placebo-treated animals that succumbed to infection primarily consisted of cutaneous vesicles, pustules, or crusts with lymphadenopathy. The only gross lesions noted at the conclusion of the study in the three surviving placebo-treated and the Day 4 treated animals consisted of resolving cutaneous pox lesions. No gross lesions attributable to poxviral infection were present in the Day 2 treated macaques. Histologic lesions in three placebo-treated macaques that succumbed to infection consisted of proliferative and necrotizing dermatitis with intracytoplasmic inclusion bodies and lymphoid depletion. The only notable histologic lesion in the Day 4 treated macaques was resolving dermatitis; no notable lesions were seen in the Day 2 treated macaques. Variola virus was detected in all three placebo-treated animals that succumbed to infection prior to the study's conclusion by all utilized methods (IHC, ISH, IFA, EM). None of the three placebo-treated animals that survived to the end of the study nor the animals in the two tecovirimat treatment groups showed evidence of variola virus by these methods. Our findings further characterize variola lesions in the macaque model and describe new molecular methods for variola detection.

Temporal changes in pathology and viral RNA distribution in guinea pigs following separate infection with two New World Arenaviruses.

Numerous arenaviruses have been identified throughout the Americas and a subset of these viruses cause viral hemorrhagic fever in humans. This study compared the pathology and viral RNA distribution in Hartley guinea pigs challenged with two human-disease causing New World arenaviruses, Junin virus (JUNV) or Guanarito virus (GTOV). Histopathologic analysis and RNA in situ hybridization revealed similar pathology and viral RNA distribution for both groups of animals challenged with either JUNV or GTOV on days 3, 7, 10 and 12 post exposure (PE). Gross lesions were first observed on day 7 and primarily involved the lungs and liver. The most severe histologic lesions occurred in the lymph nodes, spleen, and thymus and included lymphoid depletion and necrosis which increased in severity over time. Extensive necrosis was also observed in the bone marrow on day 12. Minimal to mild inflammation with and without necrosis was observed in the choroid plexus of the brain, choroid of the eye, intestinal tract, lung and adrenal gland. Significant liver lesions were rare, consisting predominantly of hepatocyte vacuolation. Viral RNA labeling was identified in nearly all organs examined, was often extensive in certain organs and generally increased over time starting on day 7. Our data demonstrate the guinea pig may serve as a useful model to study New World arenavirus infection in humans and for the evaluation and development of medical countermeasures.

Retrospective detection of monkeypox virus in the testes of nonhuman primate survivors.

Close contact through sexual activity has been associated with the spread of monkeypox virus (MPXV) in the ongoing, global 2022 epidemic. However, it remains unclear whether MPXV replicates in the testes or is transmitted via semen to produce an active infection. We carried out a retrospective analysis of MPXV-infected crab-eating macaque archival tissue samples from acute and convalescent phases of infection of clade I or clade II MPXV using immunostaining and RNA in situ hybridization. We detected MPXV in interstitial cells and seminiferous tubules of testes as well as epididymal lumina, which are the sites of sperm production and maturation. We also detected inflammation and necrosis during the acute phase of the disease by histological analysis. Finally, we found that MPXV was cleared from most organs during convalescence, including healed skin lesions, but could be detected for up to 37 d post-exposure in the testes of convalescent macaques. Our findings highlight the potential for sexual transmission of MPXV in humans.

Evaluation of Virulence in Cynomolgus Macaques Using a Virus Preparation Enriched for the Extracellular Form of Monkeypox Virus.

The 2022 global human monkeypox outbreak emphasizes the importance of maintaining poxvirus research, including enriching a basic understanding of animal models for developing and advancing therapeutics and vaccines. Intravenous administration of monkeypox virus in macaques is arguably one of the best animal models for evaluating the efficacy of medical countermeasures. Here we addressed one criticism of the model, a requirement for a high-titer administration of virus, as well as improving our understanding of monkeypox virus pathogenesis. To do so, we infected macaques with a challenge dose containing a characterized inoculum enriched for the extracellular form of monkeypox virus. Although there were some differences between diseases caused by the enriched preparation compared with a relatively similar unpurified preparation, we were unable to reduce the viral input with the enriched preparation and maintain severe disease. We found that inherent factors contained within the serum of nonhuman primate blood affect the stability of the monkeypox extracellular virions. As a first step to study a role of the extracellular form in transmission, we also showed the presence of this form in the oropharyngeal swabs from nonhuman primates exposed to monkeypox virus.

Detailed analysis of the pathologic hallmarks of Nipah virus (Malaysia) disease in the African green monkey infected by the intratracheal route.

Disease associated with Nipah virus infection causes a devastating and often fatal spectrum of syndromes predominated by both respiratory and neurologic conditions. Additionally, neurologic sequelae may manifest months to years later after virus exposure or apparent recovery. In the two decades since this disease emerged, much work has been completed in an attempt to understand the pathogenesis and facilitate development of medical countermeasures. Here we provide detailed organ system-specific pathologic findings following exposure of four African green monkeys to 2.41×105 pfu of the Malaysian strain of Nipah virus. Our results further substantiate the African green monkey as a model of human Nipah virus disease, by demonstrating both the respiratory and neurologic components of disease. Additionally, we demonstrate that a chronic phase of disease exists in this model, that may provide an important opportunity to study the enigmatic late onset and relapse encephalitis as it is described in human disease.

Nipah virus persists in the brains of nonhuman primate survivors.

Nipah virus (NiV) is an emerging zoonotic paramyxovirus that causes highly lethal henipavirus encephalitis in humans. Survivors develop various neurologic sequelae, including late-onset and relapsing encephalitis, several months up to several years following initial infection. However, the underlying pathology and disease mechanisms of persistent neurologic complications remain unknown. Here, we demonstrate persistent NiV infection in the brains of grivets that survived experimental exposure to NiV. Encephalitis affected the entire brains, with the majority of NiV detected in the neurons and microglia of the brainstems, cerebral cortices, and cerebella. We identified the vascular endothelium in the brain as an initial target of NiV infection during the acute phase of disease, indicating a primary path of entry for NiV into the brain. Notably, we were unable to detect NiV anywhere else except the brains in the examined survivors. Our findings indicate that late-onset and relapsing encephalitis of NiV in human survivors may be due to viral persistence in the brain and shed light on the pathogenesis of chronic henipavirus encephalitis.

Immune-Mediated Systemic Vasculitis as the Proposed Cause of Sudden-Onset Sensorineural Hearing Loss following Lassa Virus Exposure in Cynomolgus Macaques.

Lassa virus (LASV) causes a severe, often fatal hemorrhagic disease in regions in Africa where the disease is endemic, and approximately 30% of patients develop sudden-onset sensorineural hearing loss after recovering from acute disease. The causal mechanism of hearing loss in LASV-infected patients remains elusive. Here, we report findings after closely examining the chronic disease experienced by surviving macaques assigned to LASV exposure control groups in two different studies. All nonhuman primates (NHPs) developed typical signs and symptoms of Lassa fever, and seven succumbed during the acute phase of disease. Three NHPs survived beyond the acute phase and became chronically ill but survived to the study endpoint, 45 days postexposure. All three of these survivors displayed continuous disease symptoms, and apparent hearing loss was observed using daily subjective measurements, including response to auditory stimulation and tuning fork tests. Objective measurements of profound unilateral or bilateral sensorineural hearing loss were confirmed for two of the survivors by brainstem auditory evoked response (BAER) analysis. Histologic examination of inner ear structures and other tissues revealed the presence of severe vascular lesions consistent with systemic vasculitides. These systemic immune-mediated vascular disorders have been associated with sudden hearing loss. Other vascular-specific damage was also observed to be present in many of the sampled tissues, and we were able to identify persistent virus in the perivascular tissues in the brain tissue of survivors. Serological analyses of two of the three survivors revealed the presence of autoimmune disease markers. Our findings point toward an immune-mediated etiology for Lassa fever-associated sudden-onset hearing loss and lay the foundation for developing potential therapies to prevent and/or cure Lassa fever-associated sudden-onset hearing loss.IMPORTANCE Lassa virus is one of the most common causes of viral hemorrhagic fever. A frequent, but as yet unexplained, consequence of infection with Lassa virus is acute, sudden-onset sensorineural hearing loss in one or both ears. Deafness is observed in approximately 30% of surviving Lassa fever patients, an attack rate that is approximately 300% higher than mumps virus infection, which was previously thought to be the most common cause of virus-induced deafness. Here, we provide evidence from Lassa virus-infected cynomolgus macaques implicating an immune-mediated vasculitis syndrome underlying the pathology of Lassa fever-associated deafness. These findings could change the way human Lassa fever patients are medically managed in order to prevent deafness by including diagnostic monitoring of human survivors for onset of vasculitides via available imaging methods and/or other diagnostic markers of immune-mediated vascular disease.

Coccidioidomycosis in Nonhuman Primates: Pathologic and Clinical Findings.

Coccidioidomycosis in nonhuman primates has been sporadically reported in the literature. This study describes 22 cases of coccidioidomycosis in nonhuman primates within an endemic region, and 79 cases of coccidioidomycosis from the veterinary literature are also reviewed. The 22 cases included baboons ( n = 10), macaques ( n = 9), and chimpanzees ( n = 3). The majority died or were euthanized following episodes of dyspnea, lethargy, or neurologic and locomotion abnormalities. The lungs were most frequently involved followed by the vertebral column and abdominal organs. Microscopic examination revealed granulomatous inflammation accompanied by fungal spherules variably undergoing endosporulation. Baboons represented a large number of cases presented here and had a unique presentation with lesions in bone or thoracic organs, but none had both intrathoracic and extrathoracic lesions. Although noted in 3 cases in the literature, cutaneous infections were not observed among the 22 contemporaneous cases. Similarly, subclinical infections were only rarely observed (2 cases). This case series and review of the literature illustrates that coccidioidomycosis in nonhuman primates reflects human disease with a varied spectrum of presentations from localized lesions to disseminated disease.

Combination Kinase Inhibitor Treatment Suppresses Rift Valley Fever Virus Replication.

Viruses must parasitize host cell translational machinery in order to make proteins for viral progeny. In this study, we sought to use this signal transduction conduit against them by inhibiting multiple kinases that influence translation. Previous work indicated that several kinases involved in translation, including p70 S6K, p90RSK, ERK, and p38 MAPK, are phosphorylated following Rift Valley fever virus (RVFV) infection. Furthermore, inhibiting p70 S6K through treatment with the FDA approved drug rapamycin prevents RVFV pathogenesis in a mouse model of infection. We hypothesized that inhibiting either p70 S6K, p90RSK, or p90RSK’s upstream kinases, ERK and p38 MAPK, would decrease translation and subsequent viral replication. Treatment with the p70 S6K inhibitor PF-4708671 resulted in decreased phosphorylation of translational proteins and reduced RVFV titers. In contrast, treatment with the p90RSK inhibitor BI-D1870, p38MAPK inhibitor SB203580, or the ERK inhibitor PD0325901 alone had minimal influence on RVFV titers. The combination of PF-4708671 and BI-D1870 treatment resulted in robust inhibition of RVFV replication. Likewise, a synergistic inhibition of RVFV replication was observed with p38MAPK inhibitor SB203580 or the ERK inhibitor PD0325901 combined with rapamycin treatment. These findings serve as a proof of concept regarding combination kinase inhibitor treatment for RVFV infection.

A DNA vaccine delivered by dermal electroporation fully protects cynomolgus macaques against Lassa fever.

Lassa virus (LASV) is an ambisense RNA virus in the Arenaviridae family and is the etiological agent of Lassa fever, a severe hemorrhagic disease endemic to West and Central Africa. 1,2 There are no US Food and Drug Administration (FDA)-licensed vaccines available to prevent Lassa fever. 1,2 in our previous studies, we developed a gene-optimized DNA vaccine that encodes the glycoprotein precursor gene of LASV (Josiah strain) and demonstrated that 3 vaccinations accompanied by dermal electroporation protected guinea pigs from LASV-associated illness and death. Here, we describe an initial efficacy experiment in cynomolgus macaque nonhuman primates (NHPs) in which we followed an identical 3-dose vaccine schedule that was successful in guinea pigs, and a follow-on experiment in which we used an accelerated vaccination strategy consisting of 2 administrations, spaced 4 weeks apart. In both studies, all of the LASV DNA-vaccinated NHPs survived challenge and none of them had measureable, sustained viremia or displayed weight loss or other disease signs post-exposure. Three of 10 mock-vaccinates survived exposure to LASV, but all of them became acutely ill post-exposure and remained chronically ill to the study end point (45 d post-exposure). Two of the 3 survivors experienced sensorineural hearing loss (described elsewhere). These results clearly demonstrate that the LASV DNA vaccine combined with dermal electroporation is a highly effective candidate for eventual use in humans.

Immune plasma for the treatment of severe influenza: an open-label, multicentre, phase 2 randomised study.

BACKGROUND: Influenza causes substantial morbidity and mortality despite available treatments. Anecdotal reports suggest that plasma with high antibody titres to influenza might be of benefit in the treatment of severe influenza. METHODS: In this randomised, open-label, multicentre, phase 2 trial, 29 academic medical centres in the USA assessed the safety and efficacy of anti-influenza plasma with haemagglutination inhibition antibody titres of 1:80 or more to the infecting strain. Hospitalised children and adults (including pregnant women) with severe influenza A or B (defined as the presence of hypoxia or tachypnoea) were randomly assigned to receive either two units (or paediatric equivalent) of anti-influenza plasma plus standard care, versus standard care alone, and were followed up for 28 days. The primary endpoint was time to normalisation of patients' respiratory status (respiratory rate of ≤20 breaths per min for adults or age-defined thresholds of 20-38 breaths per min for children) and a room air oxygen saturation of 93% or more. This study is registered with ClinicalTrials.gov, number NCT01052480. FINDINGS: Between Jan 13, 2011, and March 2, 2015, 113 participants were screened for eligibility and 98 were randomly assigned from 20 out of 29 participating sites. Of the participants with confirmed influenza (by PCR), 28 (67%) of 42 in the plasma plus standard care group normalised their respiratory status by day 28 compared with 24 (53%) of 45 participants on standard care alone (p=0·069). The hazard ratio (HR) comparing plasma plus standard care with standard care alone was 1·71 (95% CI 0·96-3·06). Six participants died, one (2%) from the plasma plus standard care group and five (10%) from the standard care group (HR 0·19 [95% CI 0·02-1·65], p=0·093). Participants in the plasma plus standard care group had non-significant reductions in days in hospital (median 6 days [IQR 4-16] vs 11 days [5-25], p=0·13) and days on mechanical ventilation (median 0 days [IQR 0-6] vs 3 days [0-14], p=0·14). Fewer plasma plus standard care participants had serious adverse events compared with standard care alone recipients (nine [20%] of 46 vs 20 [38%] of 52, p=0·041), the most frequent of which were acute respiratory distress syndrome (one [2%] vs two [4%] patients) and stroke (one [2%] vs two [4%] patients). INTERPRETATION: Although there was no significant effect of plasma treatment on the primary endpoint, the treatment seemed safe and well tolerated. A phase 3 randomised trial is now underway to further assess this intervention. FUNDING: National Institute of Allergy and Infectious Diseases, US National Institutes of Health.

Rapamycin modulation of p70 S6 kinase signaling inhibits Rift Valley fever virus pathogenesis.

Despite over 60 years of research on antiviral drugs, very few are FDA approved to treat acute viral infections. Rift Valley fever virus (RVFV), an arthropod borne virus that causes hemorrhagic fever in severe cases, currently lacks effective treatments. Existing as obligate intracellular parasites, viruses have evolved to manipulate host cell signaling pathways to meet their replication needs. Specifically, translation modulation is often necessary for viruses to establish infection in their host. Here we demonstrated phosphorylation of p70 S6 kinase, S6 ribosomal protein, and eIF4G following RVFV infection in vitro through western blot analysis and in a mouse model of infection through reverse phase protein microarrays (RPPA). Inhibition of p70 S6 kinase through rapamycin treatment reduced viral titers in vitro and increased survival and mitigated clinical disease in RVFV challenged mice. Additionally, the phosphorylation of p70 S6 kinase was decreased following rapamycin treatment in vivo. Collectively these data demonstrate modulating p70 S6 kinase can be an effective antiviral strategy.

Ablation of Programmed -1 Ribosomal Frameshifting in Venezuelan Equine Encephalitis Virus Results in Attenuated Neuropathogenicity.

The alphaviruses Venezuelan equine encephalitis virus (VEEV), eastern equine encephalitis virus (EEEV), and western equine encephalitis virus (WEEV) are arthropod-borne positive-strand RNA viruses that are capable of causing acute and fatal encephalitis in many mammals, including humans. VEEV was weaponized during the Cold War and is recognized as a select agent. Currently, there are no FDA-approved vaccines or therapeutics for these viruses. The spread of VEEV and other members of this family due to climate change-mediated vector range expansion underscores the need for research aimed at developing medical countermeasures. These viruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to synthesize the viral trans-frame (TF) protein, which has previously been shown to be important for neuropathogenesis in the related Sindbis virus. Here, the alphavirus -1 PRF signals were characterized, revealing novel -1 PRF stimulatory structures. -1 PRF attenuation mildly affected the kinetics of VEEV accumulation in cultured cells but strongly inhibited its pathogenesis in an aerosol infection mouse model. Importantly, the decreased viral titers in the brains of mice infected with the mutant virus suggest that the alphavirus TF protein is important for passage through the blood-brain barrier and/or for neuroinvasiveness. These findings suggest a novel approach to the development of safe and effective live attenuated vaccines directed against VEEV and perhaps other closely related -1 PRF-utilizing viruses. IMPORTANCE: Venezuelan equine encephalitis virus (VEEV) is a select agent that has been weaponized. This arthropod-borne positive-strand RNA virus causes acute and fatal encephalitis in many mammals, including humans. There is no vaccine or other approved therapeutic. VEEV and related alphaviruses utilize programmed -1 ribosomal frameshifting (-1 PRF) to synthesize the viral trans-frame (TF) protein, which is important for neuropathogenesis. -1 PRF attenuation strongly inhibited VEEV pathogenesis in mice, and viral replication analyses suggest that the TF protein is critical for neurological disease. These findings suggest a new approach to the development of safe and effective live attenuated vaccines directed against VEEV and other related viruses.

Depletion of Alveolar Macrophages Does Not Prevent Hantavirus Disease Pathogenesis in Golden Syrian Hamsters.

UNLABELLED: Andes virus (ANDV) is associated with a lethal vascular leak syndrome in humans termed hantavirus pulmonary syndrome (HPS). The mechanism for the massive vascular leakage associated with HPS is poorly understood; however, dysregulation of components of the immune response is often suggested as a possible cause. Alveolar macrophages are found in the alveoli of the lung and represent the first line of defense to many airborne pathogens. To determine whether alveolar macrophages play a role in HPS pathogenesis, alveolar macrophages were depleted in an adult rodent model of HPS that closely resembles human HPS. Syrian hamsters were treated, intratracheally, with clodronate-encapsulated liposomes or control liposomes and were then challenged with ANDV. Treatment with clodronate-encapsulated liposomes resulted in significant reduction in alveolar macrophages, but depletion did not prevent pathogenesis or prolong disease. Depletion also did not significantly reduce the amount of virus in the lung of ANDV-infected hamsters but altered neutrophil recruitment, MIP-1α and MIP-2 chemokine expression, and vascular endothelial growth factor (VEGF) levels in hamster bronchoalveolar lavage (BAL) fluid early after intranasal challenge. These data demonstrate that alveolar macrophages may play a limited protective role early after exposure to aerosolized ANDV but do not directly contribute to hantavirus disease pathogenesis in the hamster model of HPS. IMPORTANCE: Hantaviruses continue to cause disease worldwide for which there are no FDA-licensed vaccines, effective postexposure prophylactics, or therapeutics. Much of this can be attributed to a poor understanding of the mechanism of hantavirus disease pathogenesis. Hantavirus disease has long been considered an immune-mediated disease; however, by directly manipulating the Syrian hamster model, we continue to eliminate individual immune cell types. As the most numerous immune cells present in the respiratory tract, alveolar macrophages are poised to defend against hantavirus infection, but those antiviral responses may also contribute to hantavirus disease. Here, we demonstrate that, like in our prior T and B cell studies, alveolar macrophages neither prevent hantavirus infection nor cause hantavirus disease. While these studies reflect pathogenesis in the hamster model, they should help us rule out specific cell types and prompt us to consider other potential mechanisms of disease in an effort to improve the outcome of human HPS.

Serum biomarkers of Burkholderia mallei infection elucidated by proteomic imaging of skin and lung abscesses.

BACKGROUND: The bacterium Burkholderia mallei is the etiological agent of glanders, a highly contagious, often fatal zoonotic infectious disease that is also a biodefense concern. Clinical laboratory assays that analyze blood or other biological fluids are the highest priority because these specimens can be collected with minimal risk to the patient. However, progress in developing sensitive assays for monitoring B. mallei infection is hampered by a shortage of useful biomarkers. RESULTS: Reasoning that there should be a strong correlation between the proteomes of infected tissues and circulating serum, we employed imaging mass spectrometry (IMS) of thin-sectioned tissues from Chlorocebus aethiops (African green) monkeys infected with B. mallei to localize host and pathogen proteins that were associated with abscesses. Using laser-capture microdissection of specific regions identified by IMS and histology within the tissue sections, a more extensive proteomic analysis was performed by a technique that combined the physical separation capabilities of liquid chromatography (LC) with the sensitive mass analysis capabilities of mass spectrometry (LC-MS/MS). By examining standard formalin-fixed, paraffin-embedded tissue sections, this strategy resulted in the identification of several proteins that were associated with lung and skin abscesses, including the host protein calprotectin and the pathogen protein GroEL. Elevated levels of calprotectin detected by ELISA and antibody responses to GroEL, measured by a microarray of the bacterial proteome, were subsequently detected in the sera of C. aethiops, Macaca mulatta, and Macaca fascicularis primates infected with B. mallei. CONCLUSIONS: Our results demonstrate that a combination of multidimensional MS analysis of traditional histology specimens with high-content protein microarrays can be used to discover lead pairs of host-pathogen biomarkers of infection that are identifiable in biological fluids.

Detailed analysis of the African green monkey model of Nipah virus disease.

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. African green monkeys were inoculated by the intratracheal route with 2.5 × 10(4) plaque forming units of the Malaysia strain of Nipah virus. Physiological data captured using telemetry implants and assessed in conjunction with clinical pathology were consistent with shock, and histopathology confirmed widespread tissue involvement associated with systemic vasculitis in animals that succumbed to acute disease. In addition, relapse encephalitis was identified in 100% of animals that survived beyond the acute disease phase. Our data suggest that disease progression in the African green monkey is comparable to the variable outcome of Nipah virus infection in humans.

Characterization of clinical and immunological parameters during Ebola virus infection of rhesus macaques.

The rhesus macaque serves as an animal model for Ebola virus (EBOV) infection. A thorough understanding of EBOV infection in this species would aid in further development of filovirus therapeutics and vaccines. In this study, pathological and immunological data from EBOV-infected rhesus macaques are presented. Changes in blood chemistries, hematology, coagulation, and immune parameters during infection, which were consistently observed in the animals, are presented. In an animal that survived challenge, a delay was observed in the detection of viral RNA and inflammatory cytokines and chemokines which may have contributed to survival. Collectively, these data add to the body of knowledge regarding EBOV pathogenesis in rhesus macaques and emphasize the reproducibility of the rhesus macaque challenge model.

Ebola virus disease: The use of fluorescents as markers of contamination for personal protective equipment.

The recent Ebola virus disease (EVD) outbreak has created interest in personal protective equipment (PPE) content and usage. PPE testing has historically been done by individual component, rather than as a bundle for contact isolation. Fluorescent agents are commonly used in training for infection control techniques. The purpose of our study was to compare 2 PPE bundles and to evaluate the feasibility of fluorescent markers as an assessment tool for PPE effectiveness. Eight healthcare providers volunteered for this preliminary study. Participants were randomized to 1 of 2 PPE bundles that meet current (October 20, 2014) CDC recommendations. One PPE bundle utilized commercial EVD-recommended components. The other PPE bundle used components already available at local hospitals or retail stores. Participants were also randomized to standard or high volume exposures (HVE) to simulate fluid splash. Each participant was assisted in PPE donning and doffing by an experienced trainer. A training mannequin was contaminated with fluorescent agents to simulate bodily fluids. Participants were then given clinical tasks to care for the EVD "patient." De-gowned participants were examined under "black light" for fluorescence indicative of contamination. One participant in each PPE arm had evidence of contamination. One of the contamination events was suspected during the patient care exercise. The other contamination event was not suspected until black light examination. In spite of a large difference in cost of PPE, the two bundle arms performed similarly. Bundle testing using fluorescent markers could help identify optimal PPE systems.

A Yersinia pestis tat mutant is attenuated in bubonic and small-aerosol pneumonic challenge models of infection but not as attenuated by intranasal challenge.

Bacterial proteins destined for the Tat pathway are folded before crossing the inner membrane and are typically identified by an N-terminal signal peptide containing a twin arginine motif. Translocation by the Tat pathway is dependent on the products of genes which encode proteins possessing the binding site of the signal peptide and mediating the actual translocation event. In the fully virulent CO92 strain of Yersinia pestis, the tatA gene was deleted. The mutant was assayed for loss of virulence through various in vitro and in vivo assays. Deletion of the tatA gene resulted in several consequences for the mutant as compared to wild-type. Cell morphology of the mutant bacteria was altered and demonstrated a more elongated form. In addition, while cultures of the mutant strain were able to produce a biofilm, we observed a loss of adhesion of the mutant biofilm structure compared to the biofilm produced by the wild-type strain. Immuno-electron microscopy revealed a partial disruption of the F1 antigen on the surface of the mutant. The virulence of the ΔtatA mutant was assessed in various murine models of plague. The mutant was severely attenuated in the bubonic model with full virulence restored by complementation with the native gene. After small-particle aerosol challenge in a pneumonic model of infection, the mutant was also shown to be attenuated. In contrast, when mice were challenged intranasally with the mutant, very little difference in the LD50 was observed between wild-type and mutant strains. However, an increased time-to-death and delay in bacterial dissemination was observed in mice infected with the ΔtatA mutant as compared to the parent strain. Collectively, these findings demonstrate an essential role for the Tat pathway in the virulence of Y. pestis in bubonic and small-aerosol pneumonic infection but less important role for intranasal challenge.