primary + secondary response

describe the the shape of this graph

primary response

The first time a new antigen is encountered there are only a few lymphocyte cells of each kind (<100) for the antigen to encounter, so it can take several days for clonal selection to take place and the clone army to be assembled. This is why there is a delay before antibodies are produced . There tends to also be a small clonal army. Hence the small hump.

if were infected with the same pathogen with the same antigen then again we undergo the secondary immune response. This time we dont need to go through T and B cell selection and as we have memory cells. As there is also a larger population of T and B cells ( in the form of memory cells ) these means that the clonal expansion is faster. This means that the repones is much faster and stronger

does the patient suffer symptoms in the primary response

yes as the response is slow and weak.

what are factors causing the symptoms

symptoms of the disease are shown, partly due to toxins and cell death due to the pathogen, and partly due to the immune response itself (e.g. fever, inflammation).

does the patient suffer symptoms in the secondary response

no the response is strong and fast and the pathogen is destroyed before we even have symptoms

some other pathogens develop new strains every few years do we have immunity for these

no as they have different antigens

These pathogens with many different strains show what

antigenic variation