Monkeypox virus (MPXV) infection in humans results in clinical symptoms very similar to ordinary smallpox. Aerosol is a route of secondary transmission for monkeypox, and a primary route of smallpox transmission in humans. Therefore, an animal model for aerosol exposure to MPXV is needed to test medical countermeasures. To characterize the pathogenesis in cynomolgus macaques (Macaca fascicularis), groups of macaques were exposed to four different doses of aerosolized MPXV. Blood was collected the day before, and every other day after exposure and assessed for complete blood count (CBC), clinical chemistry analysis, and quantitative PCR. Macaques showed mild anorexia, depression, and fever on day 6 post-exposure. Lymphadenopathy, which differentiates monkeypox from smallpox, was observed in exposed macaques around day 6 post-exposure. CBC and clinical chemistries showed abnormalities similar to human monkeypox cases. Whole blood and throat swab viral loads peaked around day 10, and in survivors, gradually decreased until day 28 post-exposure. Survival was not dose dependent. As such, doses of 4×104 PFU, 1×105 PFU, or 1×106 PFU resulted in lethality for 70% of the animals, whereas a dose of 4×105 PFU resulted in 85% lethality. Overall, cynomolgus macaques exposed to aerosolized MPXV develop a clinical disease that resembles that of human monkeypox. These findings provide a strong foundation for the use of aerosolized MPXV exposure of cynomolgus macaques as an animal model to test medical countermeasures against orthopoxviruses.

It is unknown whether smallpox vaccination would protect human immunodeficiency virus type 1 (HIV-1)-infected individuals, because helper CD4(+) cells, the targets of HIV-1 infection, are necessary for the induction of both adaptive CD8(+) cell and B cell responses. We have addressed this question in macaques and have demonstrated that, although smallpox vaccination is safe in immunodeficient macaques when it is preceded by immunization with highly attenuated vaccinia strains, the macaques were not protected against lethal monkeypox virus challenge if their CD4(+) cell count was <300 cells/mm(3). The lack of protection appeared to be associated with a defect in vaccinia-specific immunoglobulin (Ig) switching from IgM to IgG. Thus, vaccination strategies that bypass CD4(+) cell help are needed to elicit IgG antibodies with high affinity and adequate tissue distribution and to restore protection against smallpox in severely immunocompromised individuals.

Infection of rabbits with aerosolized rabbitpox virus (RPXV) produces a disease similar to monkeypox and smallpox in humans and provides a valuable, informative model system to test medical countermeasures against orthopoxviruses. Due to the eradication of smallpox, the evaluation of the efficacy of new-generation smallpox vaccines depends on relevant well-developed animal studies for vaccine licensure. In this study, we tested the efficacy of IMVAMUNE® [Modified Vaccinia Virus Ankara-Bavarian Nordic (MVA-BN®)] for protecting rabbits against aerosolized RPXV. Rabbits were vaccinated with either phosphate-buffered saline (PBS), Dryvax®, a single low dose of IMVAMUNE®, a single high dose of IMVAMUNE®, or twice with a high dose of IMVAMUNE®. Aerosol challenge with a lethal dose of RPXV was performed 4 weeks after the last vaccination. All PBS control animals succumbed to the disease or were euthanized because of the disease within 7 days postexposure. The rabbits vaccinated with Dryvax®, a low dose of IMVAMUNE®, or a single high dose of IMVAMUNE® showed minimal to moderate clinical signs of the disease, but all survived the challenge. The only clinical sign displayed by rabbits that had been vaccinated twice with a high dose of IMVAMUNE® was mild transient anorexia in just two out of eight rabbits. This study shows that IMVAMUNE® can be a very effective vaccine against aerosolized RPXV.

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.

Preparations of palytoxin (PLTX, derived from Japanese Palythoa tuberculosa) and the congeners 42-OH-PLTX (from Hawaiian P. toxica) and ovatoxin-a (isolated from a Japanese strain of Ostreopsis ovata), as well as a 50:50 mixture of PLTX and 42-OH-PLTX derived from Hawaiian P. tuberculosa were characterized as to their concentration, composition, in-vitro potency and interaction with an anti-PLTX monoclonal antibody (mAb), after which they were evaluated for lethality and tissue histopathology after intraperitoneal (IP) and aerosol administration to rats. Once each preparation was characterized as to its toxin composition by LC-HRMS and normalized to a total PLTX/OVTX concentration using HPLC-UV, all four preparations showed similar potency towards mouse erythrocytes in the erythrocyte hemolysis assay and interactions with the anti-PLTX mAb. The IP LD values derived from these experiments (0.92, 1.93, 1.81 and 3.26 μg/kg, for the 50:50 mix, 42-OH-PLTX, PLTX, and ovatoxin-a, respectively) were consistent with published values, although some differences from the published literature were seen. The aerosol LD values (0.063, 0.045, 0.041, and 0.031 μg/kg for the 50:50 mix, 42-OH PLTX, PLTX, and ovatoxin-a, respectively) confirmed the exquisite potency of PLTX suggested by the literature. The tissue histopathology of the different toxin preparations by IP and aerosol administration were similar, albeit with some differences. Most commonly affected tissues were the lungs, liver, heart, salivary glands, and adrenal glands. Despite some differences, these results suggest commonalities in potency and mechanism of action among these PLTX congeners.

Emerging highly pathogenic coronaviruses (CoV) are a global public health threat due to the potential for person-to-person transmission and higher mortality rates than common seasonal respiratory pathogens. Middle East respiratory syndrome coronavirus (MERS-CoV) emerged in 2012, causing lethal respiratory disease in approximately 35% of human cases.Primate models of highly pathogenic coronavirus infection are needed to support development of therapeutics or vaccines, but few models exist that recapitulate severe disease signs. For initial development of a MERS-CoV primate model, twelve African green monkeys (AGMs) were exposed to 103, 104, or 105 PFU target doses of aerosolized MERS-CoV. We observed a dose- dependent increase of respiratory disease signs and viral titers in serum and throat swabs between the 103 PFU and the 105 PFU dose groups, although all AGMs survived for the 28 day duration of the study. This study is the first to describe dose-dependent effects of highly pathogenic coronavirus infection of primates and uses a route of infection (small particle aerosol) with potential relevance to MERS-CoV transmission in humans. Aerosol exposure of AGMs may provide a platform for the development of primate models of novel coronavirus disease, with potential utility in therapeutic development and viral pathogenesis studies.

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S ince 2002, three novel coronaviruses have emerged into human populations, causing severe respiratory disease: severe acute respiratory syndrome coronavirus (SARS-CoV) during 2002-2004; Middle East respiratory syndrome coronavirus (MERS-CoV), starting in 2012; and most recently, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), starting in 2019 (1,2). All 3 of these highly pathogenic coronaviruses can cause lethal respiratory disease characterized by acute atypical pneumonia. Subclinical or asymptomatic infection has been reported for both MERS-CoV and SARS-CoV-2, but the actual number of asymptomatic infections and the pathogenesis of mild cases are not well understood (3,4). Onset of clinical disease from highly pathogenic coronaviruses typically follows an incubation period of 2-14 days, beginning as mild and nonspecific influenza-like illness including fever, fatigue, rhinorrhea, or dry cough. Many patients progress to symptoms of dyspnea and atypical pneumonia, often requiring hospitalization or supportive medical intervention, including ventilation. Coronaviridae is a family of positive-sense, singlestranded RNA genome enveloped viruses that includes the genera alphacoronavirus, betacoronavirus, gammacoronavirus, and deltacoronavirus. Highly pathogenic coronaviruses, including SARS-CoV, MERS-CoV, and SARS-CoV-2 (all betacoronaviruses), likely emerged from bats, which are a diverse reservoir of alphacoronaviruses and betacoronaviruses (5-8). Cross-species transmission of MERS-CoV or similar zoonotic precursor viruses from bats to camels established an intermediate reservoir of MERS-CoV in dromedary camels (9). MERS-CoV replicates in the upper respiratory tract of camels, but camels demonstrate only mild disease signs, and a high percentage of camels are seropositive for MERS-CoV antibodies (10,11). The MERS-CoV enzootic cycle within dromedary camels likely facilitates continued emergence in humans, where animal workers and healthcare workers are at risk for occupational exposure to MERS-CoV transmission (12,13). Sporadic MERS cases on the Arabian Peninsula continue to seed outbreaks primarily in Saudi Arabia with the potential for exported MERS cases by travelers to other regions. A major outbreak of MERS occurred in 2015 in South Korea, where a single case in a traveler returning from Saudi Arabia resulted in 186 cases and an additional ≈16,000 contacts were traced to prevent viral spread (13). Outbreaks of MERS since 2012 have resulted in a total of >2,500 cases of MERS, whereas 8,096 cases were