A previously healthy 8-year-old boy is infected with an upper respiratory tract virus for the first time. During the first few hours of infection, which one of the following events occurs?
a. The adaptive immune system responds rapidly to the virus and keeps the viral infection under control.
b. The innate immune system responds rapidly to the viral infection and keeps the viral infection under control.
c. Passive immunity mediated by maternal antibodies limits the spread of infection.
d. B and T lymphocytes recognize the virus and stimulate the innate immune response.
e. The virus causes malignant transformation of respiratory mucosal epithelial cells, and the malignant cells are recognized by the adaptive immune system
Answer:
b. The innate immune system responds rapidly to the viral infection and keeps the viral infection under control.
Step-by-step explanation:
In the invent of a newly encountered virus, the first line of defense is the innate immune response consisting of chemical, physical and cellular response. This generate a response to stop the spread of the microbes throughout the body of an individual. This is the immune system that provides an immediate response in the body of the 8-year-old boy during the first few hours of infection, before the adaptive immune response is formed later.
B and T lymphocytes are not the initiators of the innate immune response. They belong to the adaptive immune system. The adaptive immune system is not immediate, and cannot respond rapidly to the infection. It takes time to form, and is long-lasting, unlike the innate immune system.
At 8 years of age, the boy would have stopped breast feeding, hence it is very unlikely that he would still have maternal antibodies to provide him passive immunity against the infection.