The document discusses major histocompatibility complex (MHC) and heat shock proteins (HSP) in chickens. MHC genes encode proteins that present antigens and are involved in immune response and recognition. HSPs help proteins fold correctly and prevent aggregation. Both MHC and HSP play important roles in immune function, disease resistance, and stress response in chickens. Manipulation of these genes may help improve production traits and resistance to disease.

1. MAJOR HISTOCOMPATIBILITY
COMPLEX & HEAT SHOCK
PROTEIN
IN CHICKEN
Dr.S.Sivaramakrishnan
MVM15032(PSC)
DepartmentofPoultryScience
MadrasVeterinaryCollege

2. MHC
(Major histocompatibility complex)
A large cluster of linked genes located in
some chromosome of chicken, encode for MHS
and relate to immune response, immune
regulation and cell-cell recognition.

3. History
• MHC is a group of highly conserved genes defined by its
influence on tissue graft acceptance.
• MHC was discovered in the 1930s by Peter Gorer in his
pioneering studies of antigenic responses to transplanted
sera by inbred mouse strains (Gorer 1936)
• The chicken was the second animal species in which the
MHC was identified (Schierman and Nordskog, 1961)
• Chicken MHC has been designated as the B complex
because of its linkage with the B blood group (Briles et al.,
1950)

4. MHC function
MHC Peptides
Pathogen
T Cell

5.  Present antigen to initiate immune response with a phenomena
known as MHC restriction
 Endogenous Ag is presented to CD8+ T cell by MHC class Ⅰ
molecule
 Exogenous Ag is presented to CD4+ T cell by MHC class Ⅱ
molecule
 Participant in both humoral and cell-mediated immunity
 Act as antigen presenting structures
Biological function of MHC

6. Properties of MHC
1. MHC is polygenic it contains several
different MHC class I and MHC class II
genes - different ranges of peptide-binding
specificities.
2. MHC is highly polymorphic – multiple
variants of each gene within the population as
a whole.

7. – Class I MHC genes (B-F)
• Glycoproteins expressed on all nucleated cells
• Major function to present processed Ags to TC
– Class II MHC genes (B-L)
• Glycoproteins expressed on M, B-cells, Monocytes
• Major function to present processed Ags to TH
MHC Classes

8. – Class III MHC genes
• Products that include secreted proteins that have immune
functions. Ex. Complement system, inflammatory molecules
- Class IV MHC genes (B-G)
• expressed on erythrocytes and other cells such as liver cells, bursal and
thymic lymphoblast and stromal cells.
• The class IV MHC is involved in antibody response, which is supposed to
involve B cell repertoire and the B cell antigen recognition and binding

9. • The other unique MHC linked gene in the avian, is
the Rfp-Y that is recognised by DNA restriction
fragment pattern (Rfp) of the MHC class I, II and IV
genes in one MHC haplotype

10. 1
3
2
MHC-encoded -chain of 43kDa
Structure of MHC class I molecules
3 domain & 2m have structural & amino acid sequence
homology with Ig G domains Ig GENE SUPERFAMILY
2m
2-microglobulin, 12kDa, non-MHC encoded, non-
transmembrane, non covalently bound to -chain
Peptide antigen in a groove formed
from a pair of -helicies on a floor of anti-
parallel  strands
-chain anchored to the cell membrane

11. 2
1
and a -chain of 29kDa
MHC-encoded, -chain of 34kDa
2
1
Structure of MHC class II molecules
 and  chains anchored to the cell membrane
2 & 2 domains have structural & amino acid sequence
homology with Ig G domains Ig GENE SUPERFAMILY
No -2 microglobulin
Peptide antigen in a groove formed from a pair of -helicies
on a floor of anti-parallel  strands

13. MHC and immune response
MHC molecules interact with both the foreign
antigen and with complementary structure of
other immune cells, thereby generating an
immune response that is specific for the
inducing antigen

14. The T-/B-cell co-operation necessary for
antibody production and for the generation of
germinal centres in the spleen requires identity
at the MHC

15. Interaction of APCs and T cells, evaluated by
the in vitro proliferation of T cells in response
to specific antigen in the presence of APCs, is
also MHC-restricted.
The B-F/B-L antigens are the restriction
elements for all of these cellular interaction
phenomena.

16. The MHC effects on genetic control of immuno-
responsiveness, either due to restriction element
or through specific MHC-linked immune response
genes.
Antibody production against a variety of antigens,
such as immune response to synthetic
polypeptides, is linked to the chicken MHC
(Gunther et al., 1974)

17. Complement proteins are extremely important
in the immune reaction as a means to destroy
invading pathogens.
The levels of total serum haemolytic
complement have been associated with the
MHC in chickens.

18. MHC and disease resistance
 MHC – resistance to a specific disease concerns Marek's disease
(MD), a herpesvirus-induced lymphoma.
 Using MHC recombinants to the B-F/B-L region, partial MHC control
has been mapped.
 The MHC is associated with MD-related traits of incidence of tumour
formation, mortality and transient paralysis induced by MDV.
 The haplotype B21 conveys MD resistance to many different genetic
backgrounds.
 Variation in response to MDV by sublines that are identical at the B
locus, however, illustrates the influence of non-MHC genes on
response to MD (Bacon L.D. - 1987)

19. Selected diseases for which an association of resistance or
severity is found with the chicken MHC
Type of disease Disease
Neoplastic diseases (virally induced) Marek's disease neoplasia
Marek's disease transient paralysis
Rous' sarcomas
Lymphoid leucosis
Bacterial diseases Staphylococcus aureus
Fowl cholera (Pasteurella multocida)
Salmonella enteritidis
Parasitic diseases (coccidiosis) Eimeria tenella
Eimeria acervulina
Autoimmune diseases Autoimmune thyroiditis

20. Chicken MHC and production traits
 Economically important traits, such as juvenile and adult
mortality, body weight, fertilization rate, embryonic
mortality, hatchability and egg production are influenced
by MHC genotype (Bacon L.D. - 1987)
 Several independent studies have shown that long-term
selection for egg production traits and disease resistance
have significantly altered MHC allelic frequencies (Gavora
et al., 1986)
 From these selection studies, B2 and B21 appeared to show
overall beneficial associations with economic traits in
chickens.

21. • Birds which were aneuploid (trisomic) for the
MHC-bearing chromosome were used to map
the MHC to microchromosome 16 and to
examine the effects of MHC gene dosage on
several biological systems.

22. Selected production traits for which an association with the
MHC is found
Production traits
Body weight
Juvenile survival
Adult survival
Egg production
Hatchability
Embryonic mortality
Fertilization rate

23. Applications of MHC manipulation to the poultry
industry
 Differences between MHC types can be identified by
using serological blood typing or by restriction fragment
length polymorphism analysis of DNA and can be utilized
in several ways by the breeding industry.
 An MHC (or B blood group) allele can be used as a
pedigree marker, if it is unique to a genetic line within a
company, and thus can identify that line and any
accidental crosses made with it.

24.  MHC manipulation is to alter the frequency of alleles
in the population to improve associated traits such as
disease resistance, immune response and production
traits (Lamont, 1989).
 Future industrial applications of MHC manipulation
may include alteration of the gene copy number in
individual animals by use of natural variation or genetic
engineering (Bloom et al., 1988).

25. HEAT SHOCK PROTEINS(HSP)

26. History
• HSP Discovered in 1962 Ferruccio Ritossa (1936-
2014)
• chromosomes of salivary glands in Drosophila
melanogaster larva
• Heat shock proteins are highly conserved
molecules that are present, and can be induced, in
all eukaryotic and prokaryotic species, including
plants

27. Functions
• The primary function of these proteins is to govern the
folding and refolding mechanism of native and stress
denatured proteins.
• Unfolded polypeptides, prevent their aggregation and
thereby, potentiate the folding process.
• Hsps are also involved in diverse cellular roles such as
protein assembly, translocation and degradation.
• Hence these proteins are the essential determinants of
protein quality control in cell.

28. Classification
Based on their molecular mass and function, HSPs
are classified into six families namely;
1. Small Heat Shock Proteins (sHsp/Hsp20),
2. Hsp40 (J-class proteins),
3. Hsp60 (Caperonin),
4. Hsp70,
5. Hsp90,
6. Hsp100 proteins

29. Temp
environ
Temp
cell
Folded
Proteins
Unfolded
Proteins Aggregates
Loss of Protein
Function
Network
failure
Death
Cell
Need for HSP

31. HSP Synthesis
• Transcription of HSP genes is mediated by the
interaction of heat shock factor (HSF)
• Chickens, four HSFs have been identified
• HSF1 and HSF2 are ubiquitously expressed and
conserved.
• HSF1 – physiological and environmental stress
• HSF2 – mostly induced during differentiation and
early development.

32. • HSF1 - present in the cytoplasm as a latent monomeric molecule
that is unable to bind to DNA.
• When exposed to stress, an intracellular flux of newly
synthesised non-native proteins activates HSF1
(hyperphosphorylated)
• HSF1 is converted to phosphorylated trimers that have the
capacity to bind DNA, and which translocate from the cytoplasm
to the nucleus.
• HSF2 has the characteristics of a temperature-sensitive protein; it
is inactivated when exposed to raised temperature, and
sequestered to the cytoplasm, and is thereby prevented from
interference with HSF1 activity in stressed cells.

34. Major family Intracellular localisation Intracellular function
Hsp27 Cytoplasm/nucleus Actin dynamics
Hsp32 Cytoplasm Haem catabolism, antioxidant of properties
Hsp40 Cytoplasm/nucleus Regulates the activity of Hsp70; binds non-native
Proteins
Hsp47 ER Processing of pro-collagen; processing and/or secretion of
collagen
Hsp60 Mitochondria Bind to partly folded polypeptides and assist correct
folding. Assembly of multimeric complexes
Hsp70
HSP Location and Function

35. Hsp70 Cytoplasm/nucleus Bind to extended polypeptides. Prevent aggregation
of unfolded peptides. Dissociate some oligomers.
ATP binding. ATPase activity. Hsp70 downregulates
HSF1 activity
Hsp90 Cytoplasm Bind to other proteins. Regulate protein activity.
Prevent aggregation of refolded peptide. Correct
assembly and folding of newly synthesised protein.
Hsp90 assists the maintenance of the HSF1
monomeric state in non- stressful conditions.
Hsp110
(human)
Nucleolus/cytoplasm Thermal tolerance
Hsp105 Cytoplasm Protein refolding

36. HSPs in antigen presentation by MHC class I/II
molecules

38. HSPs and autoimmunity
• HSPs, particularly Hsp60 and Hsp70, are highly
immunogenic capable of inducing antibody production and
T cell activation.
• The antibodies and T cells against bacterial Hsp60 and
Hsp70 also recognize chicken Hsp60 and Hsp70
respectively, as a result of cross reactivity.
• These anti-Hsp60 and anti-Hsp70 anti- bodies and T cells
injure tissues and cause inflammatory reactions. Thus,
Hsp60 and Hsp70 have been implicated in the pathogenesis
of a number of autoimmune diseases and inflammatory
conditions.

39. HSP influenced on immunity

40. HSP on specific immunity

41. HSP in Disease resistance
• Zulkifli et al., 1994a and Liew et al., 2003. They reported
that stress due to neonatal feed restriction can improve
resistance to marble spleen disease and infectious bursal
disease in feed restricted chickens in comparison to those
fed ad libitum.
• Solemani et al., 2012 stated that 60% feed restriction and
60% feed restriction plus quercetin (1500mg/kg) from day 4
to 6. Resulted that both the groups had significantly lower
Salmonella enteritidis colonization and lower HSP70
expression then that of controlled chickens

42. • Zulkifli et al., 2003. conducted a trial on 36 days old
birds was administered 10 times the normal dose of live
IBD vaccine. After heat exposure , the Feed Restricted
Heat treatment birds had higher HSP70 density and
weight gain and lower bursal histological score then
their heat treatment and control birds. They concluded
that Feed Restricted Heat treatment could improve
weight gain and resistance to Infectious Bursal Disease
in male broiler chickens

43. HSP in Heat tolerance
• Yahav et al. (1997) reported that exposure to acute heat
stress resulted in enhanced synthesis of heat shock protein.
Synthesis of heat shock protein induced to a lesser extent in
tissues of broiler chicken, which acquired improved heat
tolerance, than in tissues of control chickens.
• Azim (2012) observed that exposing chicks to heat
treatment at 40ºC for 4 hours daily during the first 14 days.
He reported to improve the heat tolerance of broilers
through heat treatment during the first two weeks.

44. • Yahav and McMurtry (2001) found that thermal conditioning
of chicks results in improvements in performance and heat
tolerance at marketing age. He resulted thermal conditioning is
growth retardation followed by an immediate compensatory
growth period, which resulted in complete compensation for
the loss of weight gain, and lead to higher body weight of the
conditioned chickens at 42 day of age.

45. Conclusions
• MHC and HSP are highly conserved genes. MHC mainly acts on immune
regulation.
• HSP are extremely potent molecules, importance for physiological and
immunological process is indicated by the high degree to which their
structure and function are phylogenetically conserved.
• Through the gene mapping to develop the disease resistance breeds.
• In native chicken like Aseel are more disease resistant due to the highly
expression of MHC genes compared to commercial chicken. Likewise HSP
in native chickens highly expressed in stress conditions compared to
commercial chickens so that mortality also low in native chickens.
• Both MHC and HSP genes used to increase the production traits of the
chicken.