# Biosurfactants' Potential Role in Combating COVID-19 and Similar Future Microbial Threats
## 2 Approaches That Can Use Biosurfactants in Outbreak Prevention and Management
### Therapeutics
#### 2.1.2 Vaccines and Immunity  
Coronavirus diseases such as severe acute respiratory syndrome (2002-2003) and Middle East respiratory syndrome (2011) were completely new agents of zoonotic origin. With COVID-19 infections, a normally functioning immune system clears the virus completely without the person developing symptoms. The innate and adaptive immunity play a primary role in this process because the immune system is still unfamiliar with the pathogen and is unable to work properly in some cases. Priming or inducing immune cells (T cells, B cells, macrophages, neutrophils, etc.) is crucial for an effective adaptive response. When T cells are primed, they clear viral infected cells through a cellular immune response as well as mediating the differentiation of B cells into plasma cells and memory cells which, respectively, produce viral-specific antibodies and store a memory of the response in case the infection returns [37]. Therefore, for new infections, adaptive immunity plays an important role through T cell activation. One way to safely activate T cells is by using vaccines. Peptide antigen vaccines are effective because they can be obtained at high purity compared to whole organisms or protein vaccines. However, they are limited by low immunogenicity.  
Bacterial lipopeptides can be potent nontoxic, nonpyrogenic immunological adjuvants when coupled with antigens. They activate the immune system by signaling through toll-like receptor 2 (TLR2). Activity can vary considerably with different structures of lipopeptides providing great flexibility in the design of vaccine systems [38]. [PERSON] and colleagues used lipopeptides as adjuvants with viral peptides to prime viral-specific cytotoxic T cells which are a component of the cellular immune response against viral infections. For activation to occur, T cells must recognize peptides from the virus coupled with the MHC (major histocompatibility complex) class I molecules displayed by cells infected by the virus. Tripalmitoyl-S-glycerlycsteinyl-seryl-serine lipopeptide has been covalently attached to a synthetic viral peptide which produced the same cytotoxic T cells mediated immune response observed with a live and infectious virus [39]. These formulations can prove to be effective in cases where there is no initial immunity to a pathogen, or as a resort to boost immunity in combination with other therapy.  
The development of effective formulations with adjuvants that can safely boost immunity and enhance activity is a major challenge in vaccine development [40]. Some previous studies have investigated the role of surfactants in defense using bioactive peptides for the inactivation of enveloped viruses. The viral cycle of the influenza virus, for example, was reportedly inhibited by Cyclosporin A biopeptide produced by a fungus known as _Tolypocladium inflatum_ through impeding viral assembly, or the budding (exiting step), after protein synthesis [41]. It was hypothesized that targeting these latter stages in the viral life cycle can overcome the problem of resistance for antiviral drugs, and hence limit disease spread.