Encapsulated Countermeasure Strategies for Protection Against Aerosolized Pathogens
Abstract
Many viruses that are transmitted naturally by insect vectors such as mosquitoes are the causative agents for natural outbreaks of human disease. Venezuelan Equine Encephalitis Virus (VEEV) is one such viral agent, an alphavirus that is naturally transmitted by infected mosquitoes and, when transmitted to a human host, often results in a self-limiting, febrile illness with flu-like symptoms. Very rarely do natural infections by VEEV result in encephalitic outcomes and mortality. However, the threat to human health, civilian and Warfighter, increases significantly if the infection were to be acquired through the respiratory route. VEEV is highly stable and infectious as an aerosol and if the Warfighter were to be exposed, the virus has a higher likelihood of causing encephalitic disease. The encephalitic outcome is facilitated because the aerosol transmitted virus will infect the olfactory neurons in the nasal environment, which provides a direct freeway for the virus to the brain, bypassing the blood-brain barrier (BBB). Once in the brain, the virus tends to multiply very rapidly, also contributing to a concomitantly explosive neuroinflammation. Cumulatively, the infection in the brain will result in short-term encephalitis and potential long-term neurological sequelae, including the potential for development of seizures. An important problem in treating such aerosol exposures is that the treatment strategy needs to be rapid, localized, and the protective activity available for longer windows of time. At this time, such a robust intervention strategy does not exist for pathogens such as VEEV. Currently, there are no Food and Drug Administration (FDA)-approved therapeutics, prophylactics, or vaccines that are available to protect the Warfighter from aerosolized VEEV or related alphaviruses. In this effort, we identify the lack of locally acting intervention strategies that can prevent the very early establishment of an infection in the nasal environment if VEEV were to be inhaled as an aerosolized virus. To that end, we propose a strategy in which we will encapsulate virus directed siRNAs (v-siRNAs) that can selectively bind only to viral genomes and inhibit viral RNA replication. By specifically inhibiting viral replication, this increases specificity, decreases nonspecific toxicity to the host, and effectively controls virus multiplication. By encapsulating these v-siRNAs, we propose a strategy to increase their availability in the nasal epithelium for a longer window of time, thus increasing the possibility to curtain viral replication while also decreasing dosage numbers. We suggest to create several cocktail formulations of the v-siRNAs that will be encapsulated and evaluated for ability to control viral multiplication in cell culture models. Performing the experiments in cell culture models first will enable us to prioritize and down-select our most effective v-siRNA encapsulated formulations that we propose to subsequently test in a mouse model of intranasal infection by VEEV. In this mouse model, intranasal exposure to VEEV, if untreated, will result in a lethal outcome. We propose to treat the animal intranasally with the v-siRNA encapsulation and subsequently challenge with virus, to quantify the extent of protection and survival advantage conferred to the animal by the treatment. Pending demonstration of success, we will pursue additional efforts to demonstrate protection in small and large animal models with fully aerosolized virus. These long-term efforts will be part of our efforts to acquire FDA approval in the form of an Investigational New Drug application, thus bring translational value to this discovery effort. This platform, which is a proof-of-concept demonstration at this time, will then be extended to several other aerosol-transmitted pathogens that pose a threat to the Warfighter and civilian populations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 05, 2019
- Source ID
- W81XWH1910103XX0
Entities
People
- Aarthi Narayanan
Organizations
- George Mason University
- United States Army