Crimean-Congo hemorrhagic fever virus (CCHFV) is a tick-borne virus capable of causing a severe hemorrhagic fever disease in humans. There are currently no licensed vaccines to prevent CCHFV-associated disease. We developed a DNA vaccine expressing the M-segment glycoprotein precursor gene of CCHFV and assessed its immunogenicity and protective efficacy in two lethal mouse models of disease: type I interferon receptor knockout (IFNAR-/-) mice; and a novel transiently immune suppressed (IS) mouse model. Vaccination of mice by muscle electroporation of the M-segment DNA vaccine elicited strong antigen-specific humoral immune responses with neutralizing titers after three vaccinations in both IFNAR-/- and IS mouse models. To compare the protective efficacy of the vaccine in the two models, groups of vaccinated mice (7–10 per group) were intraperitoneally (IP) challenged with a lethal dose of CCHFV strain IbAr 10200. Weight loss was markedly reduced in CCHFV DNA-vaccinated mice as compared to controls. Furthermore, whereas all vector-control vaccinated mice succumbed to disease by day 5, the DNA vaccine protected >60% of the animals from lethal disease. Mice from both models developed comparable levels of antibodies, but the IS mice had a more balanced Th1/Th2 response to vaccination. There were no statistical differences in the protective efficacies of the vaccine in the two models. Our results provide the first comparison of these two mouse models for assessing a vaccine against CCHFV and offer supportive data indicating that a DNA vaccine expressing the glycoprotein genes of CCHFV elicits protective immunity against CCHFV.

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the unique RET mutations was not possible when the derivative curves overlapped. Although not all pathogenic RET mutations were available for analysis, a recent systematic study of high-resolution melting detection of heterozygous point mutations within a PCR amplicon found a sensitivity and specificity of 100% for amplicons Ͻ400 bp in size (15 ). High-resolution melting analysis for mutation scanning is a rapid (1-2 min after PCR), costeffective assay that requires no processing or separation steps. As applied to RET mutation scanning, accuracy of heterozygote detection appears to be 100%, and some (but not all) sequence variations can be distinguished from each other. Because samples are immediately available for further processing after high-resolution melting analysis, the detected variant samples can be sequenced for confirmation of genotype.

We evaluated the immunogenicity and protective efficacy of a DNA vaccine expressing codon-optimized envelope glycoprotein genes of Venezuelan equine encephalitis virus (VEEV) when delivered by intramuscular electroporation. Mice vaccinated with the DNA vaccine developed robust VEEV-neutralizing antibody responses that were comparable to those observed after administration of the live-attenuated VEEV vaccine TC-83 and were completely protected from a lethal aerosol VEEV challenge. The DNA vaccine also elicited strong neutralizing antibody responses in rabbits that persisted at high levels for at least 6 months and could be boosted by a single additional electroporation administration of the DNA performed approximately 6 months after the initial vaccinations. Cynomolgus macaques that received the vaccine by intramuscular electroporation developed substantial neutralizing antibody responses and after an aerosol challenge had no detectable serum viremia and had reduced febrile reactions, lymphopenia, and clinical signs of disease compared to those of negative-control macaques. Taken together, our results demonstrate that this DNA vaccine provides a potent means of protecting against VEEV infections and represents an attractive candidate for further development.Venezuelan equine encephalitis virus (VEEV) is a nonsegmented, positive-sense RNA virus of the genus Alphavirus in the family Togaviridae (17). Naturally transmitted by mosquitoes through rodent hosts, VEEV is highly pathogenic for equines and humans and has sporadically caused widespread epidemics in North, Central, and South America (48). While most equine and human outbreaks have been caused by the epizootic IAB and IC subtypes of VEEV, isolated cases of disease caused in equines and humans by infection with the enzootic ID and IE subtypes have also been reported (10,32,50). Regardless of the variety, human infection with VEEV typically results in an acute, incapacitating, but self-limiting disease characterized by fever, headache, lymphopenia, myalgia, and malaise (3). Severe neurological disease, including fatal encephalitis, can also result from VEEV infection of humans, although the case fatality rate is estimated to be low (Յ1%) (45). However, numerous documented laboratory accidents and the results of animal studies have demonstrated that VEEV is also highly infectious in aerosols, and infection with aerosolized VEEV could potentially result in higher mortality than that observed with natural infection (15,18,26). In addition to producing incapacitating or lethal infections and being infectious in aerosols, VEEV is also easily grown to high titers in inexpensive and unsophisticated cell culture systems and is relatively stable (45). As a result, VEEV represents a significant potential biological defense threat and is classified as a category B priority biodefense agent by both the Centers for Disease Control and Prevention and the National Institute of Allergy and Infectious Diseases.There are no licensed human vaccines for VEEV. While live-attenuated...

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