Katayoon Rahmani,1,*
1. Msc of Molecular Genetic Department of Genetics, Zanjan Branch, Islamic Azad University, Zanjan, Iran.
Introduction: The immune system is the best natural defense against pathogens (such as viruses, bacteria, protozoa, fungi, and worms). This study aimed to review data related to natural immunity against coronation.
Methods: studies on natural immunity to the coronavirus were studied by searching scientific databases such as Google Scholar, Science Direct, and PubMed.
Results: The results of some of the studies have shown that the humoral response may be transient and incomplete, but in some people, strong immune responses and neutralizing antibodies have been seen after infection. temporary antibodies protection against coronavirus infection has been reported by General studies. The results showed that after the antibody level improved after 6 months, the infection significantly decreased. Studies of COVID-19 infection in China, in patients with and without symptoms, have shown that asymptomatic patients have an incomplete and transient immune response by decreasing IgG and neutralizing antibody levels. On the other hand, experiments showed reduced mortality related to plasma usage including high antibodies to hospitalized COVID-19 patients. The cellular immunity role in the defense against COVID-19 has been confirmed by some research. In patients with severe COVID-19 infections, lymphopenia occurs and also, and CD4 and CD8 T-cells decrease. Studies have confirmed that T CD8þ cell memory is approximately associated with the severity of different COVID-19. Le Bert and coworkers showed that COVID-19 results in long-term T-cell immunity to a structural protein of SARS-CoV-2. Grifoni et al studied the roles of viral proteins that successfully stimulate T cells. They then investigated the cells of some of the patients who had recovered from COVID-19 with viral protein components and showed that all patients had helper T cells sensitive to spike SARS-CoV-2 protein.
Conclusion: According to recent findings, antibodies against SARS-CoV-2 are developed in most of the recovered patients. Scientists are uncertain, however, if enough antibodies are produced to ensure future safety, what constitutes a good level of immunity, or how long protection lasts. Based on immune responses to closely related viruses such as those that cause SARS and the Middle East respiratory syndrome (MERS), current estimates suggest that a high percentage of improved people may be protected against re-infection for one to two years due to humoral immunity and cellular immunity.