Inflammatory barriers is a type of Innate Immunity. Tissue damage and infection induce leakage of vascular fluid, containing chemotactic signals like serotonin, histamine and prostaglandins.

Interferons are a group of signalling proteins produced by virus infected cells. They interfere with viral replication and hence named interferons. A virus infected cell releases interferons which induce antiviral state in the uninfected cells. They are chemical mediators under physiological barriers offering Innate immunity.

The type of barrier that involves macrophages are the
(i) Phagocytic barriers which is a type of innate immunity.
(ii) In this mechanism, specialised cells such as monocytes, Neutrophils and tissue macro phages pha cytose and digest whole microorganisms.

Porter and Edelman revealed the basic structure of the immunoglobulin. An antibody molecule is Y shaped structure that comprises of four polypeptide chains, two identical light chains (L) of molecular weight 25,000 Da (approximately 214 amino acids) and two identical heavy chains (H) of molecular weight 50,000 Da (approximately 450 amino acids). The polypeptide chains are linked together by di-sulphide (S-S) bonds. One light chain is attached to each heavy chain and two heavy chains are attached to each other to form a Y shaped structure. Hence, an antibody is represented by H₂ L₂.

(i) After getting into the body of the person, the virus enters into macrophages where RNA genome of the virus replicates to form viral DNA with the help of the enzyme reverse transcriptase.
(ii) This viral DNA gets incorporated into the DNA of host cells and directs the infected cells to produce viral particles.
(iii) The macrophages continue to produce virus and in this way acts like a HIV factory.
(iv) Simultaneously, HIV enters into helper T-Iymphocytes, replicates and produces progeny viruses. The progeny viruses released in the blood attack other helper T-lymphocytes. The process is repeated.
(v) During this period, the person suffers from bouts of fever, diarrhoea and weight loss. Due to decrease in the number of helper T lymphocytes, the person starts suffering from infections and becomes immune deficient and unabie to protect against any infection.

S.No	Autoimmune disease	Immunodeficiency disease
i.	If the immune system of the body fails to distinguish foreign molecules from self, then it reacts destructively against the host's own molecules. This is known as autoimmune disease.	An immunodeficiency disease results from the failure of one or more components of the immune system which could be due to genetic reasons, radiation, infections etc.,
ii.	Eg: Multiple sclerosis is a autoimmune disease	Eg: AIDS is a Immunodeficiency disease.

A vaccine is a biological preparation that provides active acquired immunity to a particular disease and resembles a diseasecausing microorganism and is often made from weakened or atlenuated or killed forms of the microbes, their toxins, or one of its surface proteins. The vaccines are classified as first, second and third generation vaccines.

opsonisation or enhanced attachment is a type of antigen-antibody reaction. It is a process by which a pathogen is marked of ingestion and destruction by a phagocyte. Opsonisation involves the binding of an opsonin i.e. antibody, to a receptor on the pathogen's cell membrane. After opsonin binds to the membrane, phagocytes are attracted to the pathogen. So, opsonisation is a process in which pathogens are coated with a substance called an opsonin, marking the pathogen out for destruction by the immune system. This results in a much more efficient phagocytosis.