Conclusion:
ND virus I2 strain that was used in this experiment is heat resistant and among other lentogenic strains, it grows the most in chicken embryos.
People may infected with ND but causes conjunctivitis only.(23) Laboratory workers and vaccinator crews are the major ones who may be infected with ND but there are no known reports of transmission to humans via poultry such as transmission from meat processing or meat consumption, etc. On this basis it can be concluded that Newcastle should not pose any potential risk to human health.(1,26)
Before using ND for the treatment of Covid-19, several possible events imagined after ND inoculation.
1-Interference of Newcastle virus with Covid-19 would not be carried out and so nothing would happen .
2- Other possibility was that with the presence of Covid-19 disease , the patient would get a new disease .
3-Interference of ND with Covid-19 would be done like co-infection with IBV.
The third possibility happened. The phenomenon of interference between ND and Covid-19 virus was created and the patient recovered quickly.
It is not possible to determine the real cause or causes the phenomenon, but based on the articles of co-infection ND and IB in birds, some facts can be stated.
- As mentioned, ND did not worsen the pathological condition of the covid-19 patient and even no new disease symptoms were observed.(3)
- Covid-19 and ND viruses enter the cells through different receptors , so can be imagined both of them penetrate in one cell .
-ND virus particles, which is more than 10-8 /ml , could take over the cell’s genome production factory and interfered with replication of covid-19 virus. (17)
- The increasing interferon due to the multiplication of the ND virus. (21)
It has been said in co-infection ND and Avian influenza virus(AI) , the results in different birds are not the same, and in turkeys did not affect the replication of any of the them.(25,31) So the treatment of Covid-19 with ND may have different effects in different populations and maybe it is ineffective in some people in countries.
If in co-infection of avian influenza with ND, infection with one virus can interfere with the replication of the other virus and modify the pathogenesis and transmission of the viruses (25), is treatment human flu disease with ND conceivable ?
The interference between viruses has already been important for researchers since the 50s. It seems this issue will be more important now when more emerging diseases have appeared.It means in zonosis diseases , which pathogenic agents which may move to different species ,biological researchers instead of waiting for viral diseases to emerge in populations , they should identify useful viruses , and use them when needed .(11)