Notice of Assignment to Oral Mucositis SIA by and between Oragenics, Inc. and Intrexon Corporation between Oragenics, Inc. and Intrexon Corporation, effective January 1, 2018

Exhibit 10.20

VIA FACSIMILE: (813) 286-7904

Oragenics, Inc.

4902 Eisenhower Boulevard, Suite 125

Tampa, FL 33634

Attention: Chief Executive Officer

VIA FACSIMILE: (813) 229-1660

Shumaker, Loop & Kendrick, LLP

101 E. Kennedy Boulevard, Suite 2800

Tampa, FL 33602

Attention: Mark Catchur, Esq.

Dear Sirs:

We are pleased to advise that Intrexon Corporation has reorganized certain of its operating divisions, including the formation of a new wholly owned subsidiary of Intrexon Corporation, ActoBio Therapeutics, Inc. (“ActoBio”). ActoBio will include all of Intrexon’s worldwide operations relating to its Actobiotic™ L. lactis human therapeutic platform, including products and programs being pursued in collaboration with Oragenics, Inc. (“Oragenics”). Please be assured this internal reorganization will not negatively impact our ongoing work with Oragenics.

This letter is Notice that effective January 1, 2018 and as permitted by Section 9.7 of the Stock Issuance Agreement effective June 9, 2015 (the “Agreement”) Intrexon has assigned rights and interests in this Agreement to ActoBio. ActoBio has agreed in writing to be bound by the Agreement as set forth in the enclosed Joinder Agreement. For your future use and reference, contact and correspondence addresses are provided on the attached sheet.

Please executed and return a copy of the enclosed Joinder Agreement to my attention and do not hesitate to contact my office if you have any questions and we appreciate your attention to this matter.

Best regards,

INTREXON CORPORATION

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