1) Your research group is investigating the possible use of genetically-engineered cells to produce a vaccine for malaria. List the pros and cons of using E. coli, Saccharomyces, and animal cells to produce the vaccine. (18)

2. For the following cases, what are the signs AND symptoms mentioned, whether the patient has them or not? (30) A) The patient was a 4-month-old female with congenital heart disease who was admitted to the hospital in January with severe respiratory distress. Five days prior to admission she had developed a cough and rhinitis. Two days later she began wheezing and was noted to have a fever. She was brought to the emergency room when she became lethargic. On examination she was agitated and coughing. She had a fever of 38.90 C, tachycardia with a pulse of 220, tachypnea with respirations of 80/min., and a blood pressure of 90/58 mm Hg. B) A 35-year-old woman is seen for easy fatigue for many months. She is now 24 weeks pregnant with her 3rd child in 3 years. She does not see any obstetrician and does not take any vitamins. Lately, she has developed a taste for eating ice. She has no other complaint. Family and past history are negative. She does not smoke or drink. Physical examination is positive for pale conjunctiva, mild spooning of nails, and an II/VI systolic murmur at left lower sternal border. Stools are negative for occult blood.

 

3. Skin & mucous membranes are two main barriers to pathogen entry. What physical & chemical factors do they have to make that possible? (10)

4. The inflammatory process involves a sequence of events. What are they & why do they occur? (12)

5. What are the functions of the FIVE type of antibodies? (15)

6. What is the importance of B cells in primary AND secondary response? (10)

7. Why is it relatively hard to find organ matches, even among relatives" [Hint: Look at the MHC genes.] (5)

 

1) Your research group is investigating the possible use of genetically-engineered cells to produce a vaccine for malaria. List the pros and cons of using E. coli, Saccharomyces, and animal cells to produce the vaccine.

pros and cons of E coli

Pros

the bacteria is easily grown in labs because it isn't picky about the required nutrients.

cons

E. coli needs to be modified

pros and cons of animal cell

pros

Animal cells would provide the genetic material that will closely resemble human DNA.

cons

Animal cells are slow growing

pros and cons of saccharomyces

pros

Saccharomyces have been effectively used to discover various gastrointestinal diseases.

cons

Saccharomyces are unicellular while humans are multicellular

 

 

2) signs and symptoms of cases mentioned

CASE A

signs and symptoms

congenital heart disease 

severe respiratory distress

coughing and rhinitis

fever

CASE B

pale conjunctiva

mild spooning of nails

fatigue

 

3) Skin & mucous membranes are two main barriers to pathogen entry.

skin

physical barrier

Physical and chemical barriers form the first line of defense when the body is invaded. The skin has thick layer of dead cells in the epidermis which provides a physical barrier. Periodic shedding of the epidermis removes microbes. The physical barrier of the skin and intestine provides the first line of defense against external perturbation at these sites. The physical barrier of the skin is formed by numerous layers of epidermal and dermal keratinocytes . The outermost layer of the epidermis is the stratum corneum, composed of as many as 100 layers of keratinized cell envelopes (corneocytes) that form a protective barrier . Barrier lipids, derived from lamellar bodies form an occlusive matrix between corneocytes . Deeper epidermal layers, including the stratum granulosum and stratum spinosum, are major producers of keratin filaments, which form a structural support for the epidermis . Finally, the basal layer of the epidermis contains stem cells that proliferate in homeostatic conditions and in response to injury in order to reconstitute the physical epidermal barrier.

Chemical Barrier

The chemical barrier of the skin is formed by numerous secreted lipids and acids. As previously mentioned, the lipid layer secreted by lamellar bodies, is important for maintaining an occlusive matrix between cells and among layers of the stratum corneum (12, 13). Site-specific lipid content also influences the microbial composition of various cutaneous body sites (4, 14). In fact, microbial composition is relatively homogenous among multiple sebaceous sites but varies greatly between sebaceous and dry skin sites (4). Pathogenic microbes are also directly inhibited by some lipids or free fatty acids

 

 

mucous membrane

The mucous membranes produce mucus that trap microbes

Microbiota augment intestinal innate immunity. Intestinal epithelial cells, which make up the physical barrier of the intestine, secrete antimicrobial peptides and proteins (AMPs). Goblet cells secrete mucus which forms an additional layer of protection against pathogens.Most mucous membranes secrete a sticky, thick fluid called mucus, which facilitates several barrier immune system functions and provides a moist environment for internal and semi-internal structures. The mucosae are highly specialized in each organ to deal with different conditions. The most variation is seen in the epithelium. In the esophagus and oropharynx, the epithelium is stratified, squamous and non-keratinising, to protect these areas from harsh or acidic foods. In the stomach it is columnar and organized into gastric pits and glands to secrete acids and pepsin. The small intestine epithelium is specialized for absorption, organized into simple columnar epithelium on protruding villi with narrow crypts that have a high surface area. The mucosal epithelium in the nasopharynx is psuedostratified and ciliated, which helps accumulate and remove mucus

 

4)The inflammatory process involves a sequence of events. What are they & why do they occur

The inflammatory response (inflammation) occurs when tissues are injured by bacteria, trauma, toxins, heat, or any other cause. The damaged cells release chemicals including histamine, bradykinin, and prostaglandins. These chemicals cause blood vessels to leak fluid into the tissues, causing swelling

signs of inflammation

The four signs of inflammation are redness , heat , swelling , and pain . 

Redness is caused by the dilation of small blood vessels in the area of injury.

events of inflammation

Acute -swelling stage

Sub-acute - regenerative stage

Chronic - scar tissue maturation and re-modelling stage

During the acute inflammatory stage, there is evident redness (erythema) and swelling due to vascular changes. Exudation of cells and chemicals cause swelling and pain. A haematoma may form if there is bleeding within the tissues. Secondarily, chemical irritants are neutralized and the area is sealed off from surrounding tissues and circulation is impaired. There is early fibroblastic cell activity. Pain is normally present at rest over a diffuse area and can be aggravated by activity. Secondary muscle spasm and guarding normally restrict passive movement. During range of movement testing, pain is felt before the tissue resistance is reached. Injuries to deep structures or poorly vascularised areas can lead to surface swelling and oedema but may not be noticeable.

The sub-acute stage is the commencement of healing and repair. Noxious chemicals are further neutralized and new capillary beds growing into the damaged areas are supported by connective tissue growth (collagen fibres) and together form granulation buds. Visible signs of inflammation start to subside and range of movement increases with pain felt at the point of tissue resistance.

The chronic inflammatory stage is the period when tissue remodelling takes place. Signs of inflammation are absent and scar tissue is maturing. Pain is felt further into the range of movement after the tissue resistance has been reached. Maturation refers to the growth of the fibroblasts to fibrocytes and remodelling refers to the organization of and shrinking of collagen fibres along the lines of stress..

 

 5)What are the functions of the FIVE type of antibodies?

The 5 types -

 IgG-  protects against bacteria, viruses, neutralises bacterial toxins, triggers complement protein systems and binds antigens to enhance the effectiveness of phagocytosis

IgM-  acts as an excellent activator of the complement system and agglutination.

 IgA-body's first-line defenses against infection. It binds to pathogens to tag them for destruction and prevents them from sticking to the epithelium, which lines the body's tissue. also associated with hypersensitive reaction

 IgD- functions as a B cell antigen receptor and may participate in B cell maturation, maintenance, activation, and silencing

 IgE--responsible for the allergic response that is mostly found in the lungs, skin, and mucosal membranes

 

 6) What is the importance of B cells in primary AND secondary response?

Primary Immune Response is the reaction of the immune system when it contacts an antigen for the first time. 

Secondary Immune Response is the reaction of the immune system when it contacts an antigen for the second and subsequent times. Appears mainly in the lymph nodes and spleen

 

The extracellular spaces are protected by the humoral immune response, in which antibodies produced by B cells cause the destruction of extracellular microorganisms and prevent the spread of intracellular infections. The activation of B cells and their differentiation into antibody-secreting plasma cells

T cell-dependent activation of B cells plays an important role in both the primary and secondary responses associated with adaptive immunity. With the first exposure to a protein antigen, a T cell-dependent primary antibody response occurs. The initial stage of the primary response is a lag period, or latent period occurs during which no antibody can be detected in serum. This lag period is the time required for all of the steps of the primary response, including naïve mature B cell binding of antigen with BCRs, antigen processing and presentation, helper T cell activation, B cell activation, and clonal proliferation. The end of the lag period is characterized by a rise in IgM levels in the serum, as T_H2 cells stimulate B cell differentiation into plasma cells. IgM levels reach their peak around 14 days after primary antigen exposure; at about this same time, T_H2 stimulates antibody class switching, and IgM levels in serum begin to decline. Meanwhile, levels of IgG increase until they reach a peak about three weeks into the primary response

During the primary response, some of the cloned B cells are differentiated into memory B cells programmed to respond to subsequent exposures. This secondary response occurs more quickly and forcefully than the primary response. The lag period is decreased to only a few days and the production of IgG is significantly higher than observed for the primary response . In addition, the antibodies produced during the secondary response are more effective and bind with higher affinity to the targeted epitopes. Plasma cells produced during secondary responses live longer than those produced during the primary response, so levels of specific antibody remain elevated for a longer period of time

 

7)Why is it relatively hard to find organ matches, even among relatives

The transplant of organs is one of the greatest therapeutic achievements nowadays. In organ transplantation, the adaptive immunity is considered the main response exerted to the transplanted tissue, since the principal target of the immune response is the MHC (major histocompatibility complex) molecules expressed on the surface of donor cells. However, we should not forget that the innate and adaptive immunities are closely interrelated and should be viewed as complementary and cooperating. When a human transplant is performed, HLA (human leukocyte antigens) molecules from a donor are recognized by the recipient's immune system triggering an alloimmune response Matching of donor and recipient for MHC antigens has been shown to have a significant positive effect on graft acceptance. This paper will present MHC, the innate and adaptive immunities, and clinical HLA testing.