The current pandemic coronavirus, severe acute respiratory syndrome–coronavirus 2 (SARS-CoV-2), was recently identified in patients with an acute respiratory syndrome, coronavirus disease 2019 (COVID-19). To compare its pathogenesis with that of previously emerging coronaviruses, we inoculated cynomolgus macaques with SARS-CoV-2 or Middle East respiratory syndrome (MERS)–CoV and compared the pathology and virology with historical reports of SARS-CoV infections. In SARS-CoV-2–infected macaques, virus was excreted from nose and throat in the absence of clinical signs and detected in type I and II pneumocytes in foci of diffuse alveolar damage and in ciliated epithelial cells of nasal, bronchial, and bronchiolar mucosae. In SARS-CoV infection, lung lesions were typically more severe, whereas they were milder in MERS-CoV infection, where virus was detected mainly in type II pneumocytes. These data show that SARS-CoV-2 causes COVID-19–like disease in macaques and provides a new model to test preventive and therapeutic strategies.

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In humans, sterile immunity against malaria can be consistently induced through exposure to the bites of thousands of irradiated infected mosquitoes. The same level of protection has yet to be achieved using subunit vaccines. Recent studies have indicated an essential function for intrahepatic parasites, the stage after the mosquito bite, and thus for antigens expressed during this stage. We report here the identification of liver-stage antigen 3, which is expressed both in the mosquito and liver-stage parasites. This Plasmodium falciparum 200-kilodalton protein is highly conserved, and showed promising antigenic and immunogenic properties. In chimpanzees (Pan troglodytes), the primates most closely related to humans and that share a similar susceptibility to P. falciparum liver-stage infection, immunization with LSA-3 induced protection against successive heterologous challenges with large numbers of P. falciparum sporozoites.

Despite the widespread use of bacillus Calmette-Gué rin vaccination, Mycobacterium tuberculosis infection remains globally the leading cause of death from a single infectious disease. The complicated and often protracted dynamics of infection and disease make clinical trials to test new tuberculosis vaccines extremely complex. Preclinical selection of only the most promising candidates is therefore essential. Because macaque monkeys develop a disease very similar to humans, they have potential to provide important information in addition to small animal models. To assess the relative merits of rhesus and cynomolgus monkeys as screens for tuberculosis vaccines, we compared the efficacy of bacillus Calmette-Gué rin vaccination and the course of infection in both species. Unvaccinated rhesus and cynomolgus monkeys both developed progressive disease with high levels of C-reactive protein, M. tuberculosis-specific IgG, and extensive pathology including cavitation and caseous necrosis. Bacillus Calmette-Gué rin vaccination protected cynomolgus almost completely toward the development of pathology, reflected in a striking 2-log reduction in viable bacteria in the lungs compared with nonvaccinated animals. Rhesus, on the other hand, were not protected efficiently by the bacillus Calmette-Gué rin. The vaccinated animals developed substantial pathology and had negligible reductions of colony-forming units in the lungs. Comparative studies in these closely related species are likely to provide insight into mechanisms involved in protection against tuberculosis.T uberculosis (TB) is the leading global cause of death from a single infectious disease (1, 2), accelerated by the HIV epidemic and appearance of multidrug-resistant Mycobacterium tuberculosis (3). The efficiency of bacillus Calmette-Guérin, the only TB vaccine available for humans, ranges between 0 and 85% (4). Improved vaccines are needed urgently, and a large number of new TB vaccine candidates and delivery systems is being tested in small animal models (5-7). Human trials to evaluate new TB vaccines will be very complex, will often occur in bacillus Calmette-Guérin-immunized populations, will be of long duration, and require large cohorts (8). Effective screens to select only the most promising candidates, delivery systems, and formulations for clinical testing will be extremely valuable. Up to now, almost all efficacy testing of TB vaccine candidates has been in the mouse and͞or guinea pig (9). A more human-like response to TB has been described in the closely related rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) macaques (reviewed in ref. 10). This similarity in response may be because several host molecules implicated in TB infections are present in man and nonhuman primates but are not found, or differ fundamentally, in mice and guinea pigs. For example, many primate species, including human, share the presence of functional Mhc-DR, -DQ, and -DP regions (11). The relevance of this structural similarity is reflected in the observation that spec...