We are facing the worldwide invasion of a new coronavirus. This follows several limited outbreaks of related viruses in various locations in a recent past (SARS, MERS). Although the main current objective of researchers is to bring efficient therapeutic and preventive solutions to the global population, we need also to better understand the origin of the newly coronavirus-induced epidemic in order to avoid future outbreaks. The present molecular appraisal is to study by a bio-infomatic approach the facts relating to the virus and itsprecursors. This article shows how 16 fragments (Env Pol and Integrase genes) from different strains, both diversified and very recent, of the HIV1, HIV2 and SIV retroviruses have high percentage of homology into parts of the genome of COVID_19. Moreover each of these elements is made of 18 or more nucleotides and therefore may have a function. They are called Exogenous Informative Elements (EIE).. Among these EIE, 12 are concentrated in a very small region of the COVID-19 genome, length less than 900 bases, i.e. less than 3% of the total length of this genome. In addition, these EIE are positioned in two functional genes of COVID-19: the orf1ab and S spike genes. Here are the two main facts which contribute to our hypothesis of a partially synthetic genome: A contiguous region representing 2.49% of the whole COVID-19 genome of which 40.99% is made up of 12 diverse fragments originating from various strains of HIV SIV retroviruses. Some of these 12 EIE appear concatenated. Notably, the retroviral part of these regions, which consists of 8 elements from various strainsof HIV1, HIV2 and SIV covers a length of 275 contiguous bases of COVID-19. The cumulative length of these 8 HIV/SIV elements represents 200 bases. Consequently, the HIV SIV density rate of this region of COVID-19 is 200/275 = 72.73%.