Question
neously capable of fighting against the "flu"
virus. This reaction of the body if made easier
by the "anti-flu" vaccine which is obtained from
Mice, as well as humans, are sponta
the inactivated virus.
The table below summarizes certain expe-
riments and results realized on mice.
Non vaccinated Results after a
period of tirne
mice, that are
infected by the
"flu" virus
Case 1 Mice are born
Multiplication of
without a thymus the virus
Case 2 Mice are born
without a thymus,
then subjected to
njections of serum
trom vaccinated
Viruses do not
disappear from
the body, but they
stop multiplying
mice
Case 3 Mice are deprived of
B lymphocytes
Viruses disappear
5
a- Referring to your acquired knowledge
and to the obtained results, explain how an
organism fights against the "flu".
.
Answer
The organism fights against the "flu" virus by producing an immune response. This response involves the activation of B lymphocytes, which produce antibodies that recognize and neutralize the virus. Additionally, T lymphocytes are activated to kill infected cells. The body's immune response can be enhanced by vaccination, which stimulates the production of specific antibodies against the virus. In the experiments with mice, it was observed that mice without a thymus or with depleted B lymphocytes had a weaker immune response and were less able to fight off the virus.