eChapters

A. Answer the following.

Q.1.    Which protein is coded by gag gene in HIV ?
Ans.     It codes for protein that form the core (p24 and p17).

Q.2.     Which protein is coded by pol gene in HIV ?
Ans.    It codes for a protein that cleaved into 4 enzymes. 

Q.3.     Which protein is coded by env gene in HIV ?
Ans.    It codes for protein that is cleaved into two proteins (gp120 and gp41).

A. Answer the following.

Q.1.    What is nude mouse ?
Ans.     Nude mice are strain of hairless  mice that fail to develop functional thymus and  devoid of CMI.

B.  Write true or false.

Q.1.     Individuals who fail to develop a functional T cell system will die from viral infections.
Ans.    True.

Q.2.    Individuals who fail to develop a functional B cell system will die from bacterial  infections.
Ans.    True.

A. Answer the following.

Q.1.     How lysozyme kills Gram + and Gram – bacteria ?
Ans.     Lysozyme kills Gram + bacteria by splitting cell wall proteoglycans and Gram – bacteria in conjunction with complement.

Q.2.     Describe the different forms of leprosy ?
Ans.     Leprosy occurs in two different forms (1) tuberculoid (2) lepromatous. Tuberculoid leprosy occurs in 80% cases. Tuberculoid leprosy patients mount a strong CMI response. These patients have few organisms in their tissues and therefore few lesions. The lesions are infiltrated with macrophages and patients show a positive delayed type hypersensitivity reaction to I/D

A.    Answer the following.

Q.1.     What are the cytokines involved in innate immunity ?
Ans.     IL-1, IL-12, IL-6, IFN-a, IFN-b and TNF- a.

Q.2.     What are the cytokines involved in adaptive immunity?
Ans.    IL-2, IL-4, IL-5, IFN-g and transforming growth factor – b (TGF- b).

Q.3.     How does superantigen differ from conventional 
antigen?
Ans.     Superantigens bind to class II MHC molecules outside of the normal peptide binding cleft. Unlike normal antigens, they are not internalized and processed by antigen presenting cells but binds directly to class II molecules. A particular superantigen can activate 5-25% 

A. Answer the following.

Q.1.     What are the key cytokines produced by Th1 cells ?
Ans.     IL-2 and IFN-g. 

Q.2.     What is class III MHC genes ?
Ans.    The class III MHC genes encode various secreted protein that have immune functions including component of C’ and molecules involved in inflammation.

B. Write true of false about the followings.

Q.1.     Macrophages, dendritic cells and B cells can acts as antigen presenting cells.
Ans.    True.

A. Answer the following.

Q.1.     What are the different enzymes used to couple with antibodies to prepare conjugates for use in ELISA?
Ans.     HRPO, Alkaline phosphate, b galactosidase, penicillinase etc.

Q.2.     What does it indicate if any woman has HI titre of > 10 for rubella ?
Ans.     It means that the woman is immune to rubella. If it is less than 10 it indicates that the woman needs to be immunized against rubella.

A. Answer the following.

Q.1.     Why the serum is inactivated at 56º C for 30 min before using it in CFT and VNT ?
Ans.     The complement and non-specific virus inhibitors are inactivated in this process.

Q.2.     What are the different enzyme and complement factors are secreted continuously by macrophages ?
Ans.     Lysozyme and Complement 2, 3, 4 and 5.

B. Write true or false about the followings.

Q.1.     The classical complement activation pathway is dependent on antigen-antibody complex.
Ans.    True.

A. Answer the following.

Q.1.     What is the percentage of different subclasses of IgG in the serum ?
Ans.     IgG1 : 65 ; IgG2 : 24 ; IgG3 : 7 ; IgG4 : 4

Q.2.     How many inter heavy chain bonds are there in different subclasses of IgG ?
Ans.     IgG1 : 2 ; IgG2 : 4 ; IgG3 : 13 : IgG4 : 2.

Q.3.     What is the half life of different subclasses of IgG ?
Ans.     IgG1, IgG2 and IgG4 : 23 days ; IgG3: 8 days.

A. Answer the following.

Q.1.     What is the difference between cell wall of Gram positive and Gram negative bacteria ?
Ans.     The cell wall of Gram positive bacteria is largely composed of peptidoglycans. These are chains of alternating N-acetylglucosamine and N-acetylmuramic acid cross linked by short peptide side chains. On the other hand, the cell wall in Gram negative bacteria has thinner peptidoglycan layer, an outer membrane composed of a polysaccharide-lipid-protein structure. The oligosaccharide attached to a lipid (lipidA) and a series of repeating trisaccharides. The polysaccharide antigens are called ‘O’ antigens. The cell wall lipopolysaccharides of Gram negative bacteria are also called endotoxins.

A. Answer the following.

Q.1.     What are the different phagocytic cells ?
Ans.     The phagocytic cells of mammals belong to two complementary systems (1) The myeloid system consists of cells that are rapidly phagocytic but incapable of sustained effect. (2) Mononuclear phagocytic system act more slowly but capable of repeated phagocytosis.

Q.2.     How 3 types of granulocytes are differentiated ?
Ans.    Three types of granulocytes are distinguished by the staining property of their granules. Cells whose granules take up basic dyes such as haematoxylin (a blue dye) are called basophils, whose granules take up acidic dyes such as eosin (a red dye) are called eosinophils and those that take up neither basic nor acidic dyes are called neutrophils.

A. Answer the following

Q.1.    What is the difference between apoptosis and necrosis?

Ans.    In apoptosis, there is pronounced decrease in cell volume, modification of cytoskeleton, condensation of chromatin and degradation of DNA into fragments. Due to these changes, an apoptotic cell sheds tiny membrane bound apoptotic bodies containing intact organelles. Macrophages phagocytose apoptotic bodies and cells in the advanced stages of apoptosis. But there is no release of proteolytic and the lytic enzyme, cationic proteins and oxidizing molecule in the surrounding tissue and no local inflammatory response. On the other hand, in necrosis cells swell and burst releasing their contents and possibly triggering a damaging inflammatory response.

Embryo Transfer (ET) refers to the technique by which embryos are collected from the reproductive tract of female (donor) and transferred to that of another female (recipient) which carries it to term. The donor and recipient female are in same stage of estrous cycle. The main objective of ET is the improvement of animal population through maximum utilization of superior females and males. It allows faster progeny testing of both male and females. By obtaining and transferring embryos from pre-pubertal females shorten the generation interval from birth to reproductive age. The superior buffaloes will be sent for slaughter after getting lactation yield in metropolitan cities. Utilizing oocytes for In-vitro maturation (IVM) and In-vitro fertilization (IVF) from such slaughtered superior buffaloes can prevent wastage of genetic material. ET allows preservation of rare and extinct species and breeds of animal. ET can be used as a basic tool for twinning, cloning, sexing and to test chromosomal aberrations.

The term transgenic animal refers to an animal in which there has been a deliberate modification of the genome - the material responsible for inherited characteristics - in contrast to spontaneous mutation (FELASA September 1992, revised February 1995). Foreign DNA is introduced into the animal, using recombinant DNA technology, and then must be transmitted through the germ line so that every cell, including germ cells, of the animal contain the same modified genetic material.  By simple means a transgenic animal is an animal in which foreign DNA has been incorporated into its original DNA. Transgenic animals are altered so that their DNA produces chemicals that normally they would not produce.

The concept of immunonutrition has been developed in humans and animals mainly in relation to its impact on reinforcement of the immune system and its ability to resist disease. However, in the case of immunology of reproduction, different (even opposite) mechanisms  of immune system modulation are likely to be involved since the main objective is a local inhibition or the attenuation of the immune system toward the protection of the embryos. Most of the studies investigating the role of feeding and /or specific nutrients have used nutrient deficiency models to identify the mechanisms involved. During recent years, an increasing number of substrates have been recognized for their immunomodulating function. Macro and micronutrients have been identified as so-called immunonutrients. Although informative, such an approach might not apply to a concept of immunonutrition for reproduction when the dietary levels of a given nutrient will have to cover both the metabolic and immunomodulation needs for optimal reproduction.

Overpopulation in humans and street dogs to some extent is a global problem of significant magnitude, with grave implications for the future. The overpopulation of dogs and cats is becoming an increasing concern in most countries of the world. As the global human population explodes so to do the staggering numbers of many best friends. Not only does this overpopulation cause millions of deaths each year and immeasurable levels of suffering in unwanted animals, these animals can cause significant risks to human health.

Stray animals particularly dogs are source of dreaded diseases like rabies and other zoonoses, resulting in thousands of deaths annually. The management of wild and domestic animal population is step towards controlling the situation and fertility control techniques play a role in this. However, such technology is still in its infancy is yet to be used on a large scale.

Advancements made in immunology and improved methods for the isolation of antigens specific reproductive system have paved the way for the development of antifertility vaccines in the past two decades. These vaccines are generally based on their ability block an indispensable step in the reproductive process.

The history of the pregnancy test is a meaningful history embedded in magic, myth, politics, and science. From ancient Egyptian to modern times, the pregnancy test holds a cultural omnipresence that forces women to confront their fertility, femininity, and their future. Today we know that a pregnancy test that detects the human hormone known as human chorionic gonadatropin (hCG) offers the quickest and most accurate result for determining pregnancy. HCG is secreted by the placenta after the fertilized egg implants in the uterus and can be detected in both urine and blood. Urine pregnancy tests are convenient for home use, but a doctor may also opt to test blood as it provides a quantitative hCG number. Both methods are highly accurate and common. Pregnancy tests, however, were not always so accurate or so culturally accepted.
 
The diagnosis of pregnancy requires a multifaceted approach using three main diagnostic tools. These are (a) history and physical examination, (b)laboratory evaluation, and (c) ultrasonography. Currently, physicians may use all of these tools to diagnose pregnancy at early gestation and to help rule out other pathologies.

In animals with a long gestation period, such as domestic animals, the acquired immune system is fully developed at birth, but cannot function at full adult levels for several weeks. The complete development of the acquired immunity depends on antigenic stimulation. The proper development of B cells and B cell antigen receptor (BCR) diversity requires clonal selection and antigen driven cell multiplication. Thus, the newborn animals are vulnerable to infection for the first few weeks of life. Hence, the temporary assistance in defending themselves at this time is provided by the mother in the form of antibodies and possibly T cells.
 
Development of the Immune System

The thymus is first lymphoid organ to develop, followed closely by the secondary lymphoid organs. B cells appear soon after the development of spleen and  lymph nodes, but antibodies are not usually found until late in foetal life, if at all. The ability of fetus to respond to antigens develops very rapidly after the lymphoid organs appear, but all antigens are not equally capable of stimulating fetal lymphoid tissue. The immune system in a series of steps, each step permitting the foetus to respond to more antigens. These steps are driven by a gradual increase in the use of gene conversion or somatic mutation to antibody diversity. The ability to mount cell mediated immune (CMI) responses develops at the time as antibody production. Data from humans suggest that T cell receptor diversity is limited in the fetus and neonate and that cytokine production may be low. This may simply be due to their lack of to foreign antigens.

Immunological Causes of Male Infertility

Immune mediated male infertility is an auto-immune disease.Spermatozoa are first produced at puberty and isolated from the systemic circulation by a structural barrier maintained by Sertoli cell tight junctions within the testis and the uninterrupted epithelial cell lining of the excurrent ductal system. Sperm production occurs well after the development of immunological tolerance to self antigens; therefore sperm specific components are viewed as foreign by the immune system. Whether spermatogonia, the primordial cell in spermatozoa differentiation, is also antigenically foreign is not established. What is known , is that immunization with sperm elicits a highly reproducible immune response that can impair fertility.

Antisperm antibodies are found in about 10-15% of infertile men. Immunity only to those antigens present on the surface of viable, motile sperm will impair fertility. Antibodies to internal sperm antigens, due to an immune response to sperm degraded in the genital tract or to cross reacting microbial antibodies present in the sera of many fertile individuals , are of questionable relevance to infertility. A number of spermatozoa antigens have been identified .

To an immunologist, the presence of embryo inside the mother’s uterus is perhaps one of the most surprising things. Pregnancy is a unique event in which a genetically and immunologically foreign foetus usually survives to full term without apparent rejection by the mother’s immune system. Thus, Pregnancy represents the unique physiological phenomenon of the symbiosis of two semi-allogeneic individuals: the mother and her fetus. Such symbiosis requires a sophisticated immunological regulation to avoid rejection-like reactions and to control the invasion of foreign foetal tissue into the maternal deciduas. A very fine tuning of cellular interactions at the interface of both individuals is indispensible for successful implantation and pregnancy.

Over the past decade, more information has been gathered to provide insight into the complex immunological mechanisms that allow the foetus to grow and survive in most cases.

I. IMMUNOLOGY OF MALE REPRODUCTIVE SYSTEM

There are two basic functions of the immune surveillance of man and animals with respect to sperm immunity during spermatogenesis and fertilization process: support of the elimination of the vast majority of 'waste "spermatozoa that fail to fertilize and preservation of the tiny minority of surviving spermatozoa that are able to fertilize the oocytes. The primordial forms of spermatozoa arising in the seminiferous tubules of testes are preserved by the blood-testes barrier which is formed by sertoli cells ringing the semineferous tubules (Hunter, 1989). During maturation in the epidydimis, the spermatozoa acquire their antigenic properties. Simultaneously, the spermatozoa are coated with some proteins of seminal plasma having the immunosuppressive activity toward lymphocytes and macrophages involved in the immune reactions. The seminal plasma proteins accompany the migration of spermatozoa to the female genital tract (Matousek, 1985).