*Review* **Current Status and Perspective on the Use of Viral-Based Vectors in Eukaryotic Microalgae**

**Omayra C. Bolaños-Martínez 1,2, Ganesan Mahendran 1,2, Sergio Rosales-Mendoza 3,4 and Sornkanok Vimolmangkang 1,2,\***

	- Correspondence: sornkanok.v@pharm.chula.ac.th; Tel.: +662-218-8358

**Abstract:** During the last two decades, microalgae have attracted increasing interest, both commercially and scientifically. Commercial potential involves utilizing valuable natural compounds, including carotenoids, polysaccharides, and polyunsaturated fatty acids, which are widely applicable in food, biofuel, and pharmaceutical industries. Conversely, scientific potential focuses on bioreactors for producing recombinant proteins and developing viable technologies to significantly increase the yield and harvest periods. Here, viral-based vectors and transient expression strategies have significantly contributed to improving plant biotechnology. We present an updated outlook covering microalgal biotechnology for pharmaceutical application, transformation techniques for generating recombinant proteins, and genetic engineering tactics for viral-based vector construction. Challenges in industrial application are also discussed.

**Keywords:** biopharmaceuticals; recombinant proteins; transient expression; viral vectors
