Evidence of venom factor-like in crocodilians

The cobra venom factor (CVF) is an unusual non-toxic complement system-activating protein reported in the venom of many family Elapidae snakes, and it is closely related to C3 complement. The archosaurs, including crocodilians, were traditionally considered a completely non-venomous group of animals; however, the identification of some related sequences similar to CVF proteins in the crocodilian genome may trigger important discussions and manage interesting hypotheses. The aim of this work was to identify VF-like protein in Caiman latirostris DNA samples. The results demonstrate the presence of VF-like in C. latirostris and showed a strong homology of VF-like and C3 complement, indicating a probable paralogy between both proteins in crocodilians. Also, these findings provide some potential explanations to justify presence of VF-like protein in crocodilians: one is based on the horizontal transfer of a transposable element from a virus as a vector, and another proposes the horizontal gene transfer by the predator-prey interaction between crocodilians and snakes. Our results are in accordance with investigations that propose the presence of snakes' venom components in non-venomous reptiles. However, more research will be needed to determine if VF-like in crocodilians has a similar function to CVF.