**4. Conclusions**

The reported antivirals discoveries call for more screening of myxobacterial-derived compounds, especially against other medically important viruses. Myxobacteria have demonstrated to be creative producers of molecules that can have valuable applications as possible lead structures for the development of antiviral drugs. Some broad-spectrum antivirals such as soraphen A could be of interest for the possibility of treating co-infection cases. Further, the possibility of using these myxobacteria derived secondary metabolites for treating both opportunistic infections and the HIV could be explored. The challenge of some compounds being toxic can be approached by structure modification for possibility of reducing toxicity while maintaining efficacy, as observed with the analogues of soraphen and noricumazoles. Moreover, some metabolites found to have potent antiviral activity may not be used as drugs themselves, due to toxicity, but they can serve as excellent tools to study and understand the viral invasion. This valuable information can be used to select other metabolites with similar mechanisms of action or structural modification of the compounds, to reduce their toxicity without substantially altering the activity. This ability of myxobacteria to produce such a vast number of secondary metabolites is most likely brought about by many years of evolution to adapt to survival in an ecological condition of competitive existence in the presence of competitors and invaders such as fungi, bacteriophages, and other bacteria. A recent comprehensive study involving molecular phylogeny with HPLC-MS profiling has revealed an unparalleled diversity of metabolites, along with strong correlations of the metabolite production to the phylogenetic position of the corresponding producer organisms [81]. Therefore, it appears promising to isolate more myxobacteria that represent novel genera and species from unexplored environments and screen them systematically for the production of further unique compounds with antiviral activities.

**Author Contributions:** Draft Preparation, L.S.M.; Editing of manuscript, M.S.

**Funding:** L.S.M. was supported by a Ph.D. grant from the DAAD-NACOSTI Scholarship funding program number (2014) 57139945 (91530969).

**Acknowledgments:** L.S.M. is highly indebted to DAAD-NACOSTI for the PhD Scholarship and TSC-Kenya for study leave. We are grateful to Joachim Wink and the technical staff of the HZI, Wera Collisi, Aileen Gollasch, Stephanie Schulz, Birte Trunkwalter and Klaus-Peter Conrad for the images of myxobacteria.

**Conflicts of Interest:** The authors declare no conflict of interest.
