The document discusses bacterial antigens, which are molecules found on bacterial surfaces that are detected by the human body's immune cells like macrophages and B cells. When B cells detect antigens, they create antibodies to mark bacteria for destruction. There are primary antibodies gathered from animals and secondary antibodies that can be tagged with fluorescent markers. While antigens allow bacteria to be detected by the human immune system, they may remain on bacteria for important functions like inter-bacterial communication through quorum sensing or because some antigens are critical for bacterial survival and highly conserved.

1. Bacterial Antigens
By, Prajwal Keranahalli

2. Definition
● A Bacterial Antigen is a molecule that is found
on the surfaces of bacterial organisms
● When detected by the human body B cells
create Antibodies to mark remaining bacteria
for destruction.

4. Main Immune Cells
● Macrophages
● B Cells
● Memory B Cells

5. Types of Antibodies
● Primary Antibodies
– Gathered from animals like Mice, rabbits, etc.
● Secondary Antibodies
– Can be tagged with fluorescent markers to determine
protein localization

6. Why Do Bacteria Have Antigens?
The human body uses antibodies as a primary way to fight
off bacterial infection. Antibodies work by binding to
antigen identifier proteins on the membranes of these
organisms. So why do so many types of bacteria still have
antigens if they just make themselves more noticeable to
their hosts.
Antigens may be used for inter-bacterial communication
but wouldn't the advantage of surviving eventually
outweigh the benefit of interaction. I say this because
bacteria are inherently unicellular organisms and so group
coordination is not a primary goal for these organisms.

7. Quorum Sensing
Autoinducers
Bonnie Bassler Ted Talk: http://tinyurl.com/nt67z9u

8. Possibility 1
The point of the adaptive immune system is that it can
in theory react to any molecular structure conceivable
without necessitating the germ-line genome to contain
a huge load of information of microbial targets.
Therefore it is quite slow which gives bacteria some
time to act.

9. Possibility 2
The detected antigens/patterns in question are highly
conserved within bacteria, because the proteins that
constitute these patterns are critical for the survival of
any bacterium as an organism
Flagella

10. Possibility 2
The detected antigens/patterns in question are highly
conserved within bacteria, because the proteins that
constitute these patterns are critical for the survival of
any bacterium as an organism
Flagella