Özet:

Viruses are the most dynamic micro beings in ecology. In terms of their structure and replication strategies, they need a host to survive in nature. This circumstance that viruses have performed in the host to survive usually creates unfavorable conditions. The proteins that the virus get to its structure and synthesized in the host cell are disease triggering factors for the host cell. Altering balances and conditions in ecology cause a continuous change in the host-virus relationship. In particular, changes in the genomic structure affect the host affinity of the viruses. These changes occurring in the virus genome are of great importance for the most developed living things in ecology, that is, human and animal health. One of the most recent examples of this is the Coronavirus Disease-19 (COVID-19) outbreak and its agent, Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2). Although it is not exactly known where or from which creature the SARS-CoV-2 originated, genetic analyzes revealed that it was close to coronaviruses found in some bat and pangolin species. This result strengthens the hypothesis that SARS-CoV-2 may be a virus with a high probability of changing the host as a result of mutations. In this context, in the review, viruses whose host affinity changed after a genetic difference was mentioned over time. In addition, considering these changes that occurred in the past, new host changes that may occur in the future and predictions about possible disease outbreaks are also included in our current review.