Natural cross-reactive anti-SARS-CoV-2 antibodies in avian egg yolk

Since the beginning of the 21st century, the Coronaviridiae family has caused several life-threatening outbreaks in the world. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which is the cause of the latest Coronaviridiae-related outbreak, is still a major health issue worldwide. Prevention, diagnosis, and therapeutic actions are the most important strategies to mitigate the spread of the COVID-19 pandemic. Among therapeutics, specific antibodies play a crucial role in controlling the symptoms of patients and preventing others from becoming infected. Here, we have introduced the avian egg yolk as a natural source of cross-reactive anti-SARS-CoV-2 immunoglobulin Y. ELISA, dot blot and western blot were used to identify natural anti-SARS-CoV-2 IgY in the egg yolk of different species of birds. Also, bioinformatics analysis was performed to investigate the possible causes of the presence of these natural antibodies in the egg yolks. The results of blotting and ELISA assays demonstrated that the egg yolk-derived antibodies could identify and bind to the different subunits of SARS-CoV-2. Substantial concentrations of neutralizing antibodies against SARS-CoV-2 were also detected in the egg yolk. In addition, bioinformatics analysis showed structural similarities between the components of infectious bronchitis virus, SARS-CoV-2, and other members of the Coronaviridiae family. It seems that egg yolk can be used as a natural, inexpensive, and accessible source of anti-SARS-CoV-2 antibodies. Diverse diagnostic and therapeutic potentials for avian egg yolk-derived anti-SARS-CoV-2 antibodies are imagined.