MDS PREP
What is the significance of HLA class I antigens in the context of graft rejection and cell mediated cytolysis?
1) They are only involved in cell-to-cell recognition in the immune system.
2) They are the principal antigens that induce an immune response in the host against transplanted tissues.
3) They have no role in graft rejection or cell-mediated immunity.
4) They are only involved in the innate immune response.
HLA class I antigens are the principal antigens that induce an immune response in the host against transplanted tissues.
What is the effect of Actinomycin D on orthomyxoviruses?
1) Stimulates multiplication
2) Inhibits multiplication
3) No effect
4) Enhances stability
General Microbiology Answer: 2Actinomycin D is an antibiotic that inhibits RNA synthesis. In the case of orthomyxoviruses, it effectively inhibits their multiplication by preventing the transcription of viral RNA, thereby blocking the virus ability to replicate. Actinomycin D inhibits the multiplication of orthomyxoviruses by blocking RNA synthesis, which is crucial for viral replication.
Which of the following bacteriophage types of diphtheria bacilli are associated with avirulent strains?
1) Type I and II
2) Type IV and VI
3) Type III
4) Type VII
Type VII bacteriophage types of diphtheria bacilli are associated with avirulent strains.
What is the name of the live oral vaccine for typhoid fever and what is its mechanism of action?
1) Typhoral, a Gal E mutant of S. typhi that "self-destructs" after a few cell divisions
2) CholeraVax, a killed whole-cell vaccine
3) Salmonellosis vaccine, a live attenuated strain of S. paratyphi
4) Shigellosis vaccine, a bacteriophage preparation
General Microbiology Answer: 1the live oral vaccine for typhoid fever is Typhoralx, which is a Gal E mutant of S. typhi. The mechanism of action involves the attenuated bacteria colonizing the intestinal mucosa and inducing an immune response that protects against subsequent infection with the pathogenic strain.
Which of the following is a feature of HLA class I antigens?
1) Found on red blood cells
2) Involved in humoral immunity
3) Present on all nucleated cells
4) Only present in lymphocytes
HLA class I antigens are present on all nucleated cells, playing a crucial role in the immune response.
Which of the following hepatitis viruses has a single-stranded RNA genome?
1) Hepatitis A
2) Hepatitis B
3) Hepatitis C
4) Hepatitis D
General Microbiology Answer: 1Hepatitis C virus (HCV) is known for its single-stranded RNA genome. This characteristic is crucial for its classification and understanding its replication cycle, which involves RNA-dependent RNA polymerase.
The most efficient method of sterilization in dental practice is
1. ultraviolet radiation
2. moist heat at 121°C for 20 min
3. boiling for 20 mm
4. dry heat at 40° C for 2 hours
Microbiology
Answer: 2
The most efficient method of sterilization in dental practice is moist heat at 121°C for 20 min
What type of vaccine is the 17D vaccine for yellow fever?
1) Live attenuated
2) Inactivated
3) Subunit
4) Toxoid
General Microbiology Answer: 1
The 17D vaccine for yellow fever is a live attenuated vaccine, meaning it contains a weakened form of the virus that can stimulate an immune response without causing the disease. This type of vaccine is effective in providing long-lasting immunity.