Zika virus emerged in the Americas where dengue virus is endemic. Within the four serotypes of dengue, antibody dependent enhancement is thought to enhance viral replication and disease severity. Reports suggest anti-dengue antibody may enhance Zika infections. We investigated whether Zika antibodies enhance dengue replication by exposing C57Bl/6 mice to Zika. Polyclonal serum was verified for strong Zika-neutralizing, dengue-subneutralizing capacity. Then we determined the enhancement capabilities of Zika-immune serum for dengue in vitro. We show that Zika antibodies do have the ability to enhance dengue infections, which is important as in many Zika-affected areas, dengue is expected to remain endemic.

Following the emergence of Zika in the past decade, there are lessons to be learned from similar emergence events of dengue (DENV) and chikungunya (CHIKV). Specifically, as Zika emerges in the Americas there is a natural tendency to apply the knowledge base of DENV and CHIKV to mitigation and control of a virus with such a similar transmission system. However, there are marked differences that may preclude such broad stroke application of this knowledge base without making potentially faulty assumptions. Herein, Zika virus (ZIKV) transmission is reviewed, and the commonalities among these three arboviruses are discussed. Importantly, the divergence of this particular arbovirus is discussed, as is the need to develop ZIKV-specific knowledge base for mitigation of this disease. Specifically reviewed are 1) emergence and persistence patterns, 2) genetic and phenotypic diversity, 3) vector host range, and finally, 4) alternate transmission routes and added complexity of ZIKV transmission and presentation.

Bunyamwera (BUNV), Batai (BATV), and Ngari (NRIV) are mosquito-borne viruses of the Bunyamwera serogroup in the Orthobunyavirus genus of the Bunyaviridae family. These three viruses have been found to cause disease in both livestock animals, avian species, and humans. Thus, these viruses pose a potential threat to human public health, animal health, and food security. This is especially the case in the developing nations, where BUNV and NRIV are found, mainly in Africa. BUNV and BATV are fairly well characterized, while NRIV is not well characterized owing to only sporadic detection in human and animal populations in Africa. Reassortment is common among bunyaviruses, but NRIV is believed to be the only natural reassortant of the Bunyamwera serogroup. It resulted from a combination of BUNV S and L segments and the BATV M segment. This indicates at least some level co-circulation of BUNV and BATV, which have no historically been reported to overlap in geographic distributions. But as these viruses are undercharacterized, there remains a gap in the understanding of how such reassortment could occur, and the consequences of such. Due to their combined wide range of hosts and vectors, geographic distributions, potential severity of associated diseases, and potential for transmissibility between vertebrate hosts, these viruses represent a significant gap in knowledge with important One Health implications. The goal of this review is to report available knowledge of and identify potential future directions for study of these viruses. As these are collectively understudied viruses, there is a relative paucity of data; however, we use available studies to discuss different perspectives in an effort to promote a better understanding of these three viruses and the public and One Health threat(s) they may pose.

Annals of Global Health is a peer-reviewed, fully open access, online journal dedicated to publishing high quality articles dedicated to all aspects of global health. The journal's mission is to advance global health, promote research, and foster the prevention and treatment of disease worldwide. Its goals are to improve the health and well-being of all people, advance health equity, and promote wise stewardship of the earth's environment. The latest journal impact factor is 2.90. Annals of Global Health is supported by the Program for Global Public Health and the Common Good at Boston College. It was founded in 1934 by the Icahn School of Medicine at Mount Sinai as the Mount Sinai Journal of Medicine. It is a partner journal of the Consortium of Universities for Global Health. From time to time, Annals of Global Health publishes Special Collections, a series of articles organized around a common theme in global health. Recent Special Collections have included "Local evidence and strategies in addressing NCDs Non-Communicable Diseases in Tanzania", "Universal Health Coverage through Integrated Care", and "The Minderoo-Monaco Commission on Plastics and Human Health". Global health workers interested in developing a Special Collection are strongly encouraged to contact the Managing Editor in advance to discuss the project.

The extrinsic incubation period is a critical component in the assessment of arboviral transmission potential. It defines the time it takes for a mosquito to become infectious following exposure to an arbovirus. Since this is a temporal process, the lifespan of a mosquito is intimately tied to the extrinsic incubation period and thus transmission potential of these viruses. Temperature is a known effector of both vector competence (the ability of a vector to transmit a pathogen) and mosquito mortality, but the interaction among temperature, vector competence, and mosquito mortality is not well characterized. Herein, we investigate this interaction for dengue virus, serotype 2, and its primary vector Aedes aegypti where we found that at 30 ^°C, infection and/or dissemination shortened the average lifespan of the mosquito and that when considering only mosquitoes with a disseminated infection, those incubated at 26 ^°C lived significantly longer.

Background: Dengue virus (DENV) research has historically been hampered by the lack of a susceptible vertebrate transmission model. Recently, there has been progress towards such models using several varieties of knockout mice, particularly those deficient in type I and II interferon receptors. Based on the critical nature of the type I interferon response in limiting DENV infection establishment, we assessed the permissiveness of a mouse strain with a blunted type I interferon response via gene deficiencies in interferon regulatory factors 3 and 7 (IRF3/7^{−/− −/−}) with regards to DENV transmission success. We investigated the possibility of transmission to the mouse by needle and infectious mosquito, and subsequent transmission back to mosquito from an infected animal during its viremic period.Methods: Mice were inoculated subcutaneously with non-mouse adapted DENV-2 strain 1232 and serum was tested for viral load and cytokine production each day. Additionally, mosquitoes were orally challenged with the same DENV-2 strain via artificial membrane feeder, and then allowed to forage or naïve mice. Subsequently, we determined acquisition potential by allowing naïve mosquitoes on forage on exposed mice during their viremic period.Results: Both needle inoculation and infectious mosquito bite(s) resulted in 100% infection. Significant differences between these groups in viremia on the two days leading to peak viremia were observed, though no significant difference in cytokine production was seen. Through our determination of transmission and acquisition potentials, the transmission cycle (mouse-to mosquito-to mouse) was completed. We confirmed that the IRF3/7^{−/− −/−}mouse supports DENV replication and is competent for transmission experiments, with the ability to use a non-mouse adapted DENV-2 strain. A significant finding of this study was that this IRF3/7^{−/− −/−}mouse strain was able to be infected by and transmit virus to mosquitoes, thus providing means to replicate the natural transmission cycle of DENV.Conclusion: As there is currently no approved vaccine for DENV, public health monitoring and a greater understanding of transmission dynamics leading to outbreak events are critical. The further characterization of DENV using this model will expand knowledge of key entomological, virological and immunological components of infection establishment and transmission events.