Virus isocaedrico

Classified in Biology

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1. What are the pathogenic Substances produced by streptococcus pygenes?

â  * invasive &pygenic infection:

 streptococcal sore throat

streptococcal pyoderma


subacute endocarditis

the most common bacterial cause of sore Throat


poststreptococcal sequelae.

2.Explain the mechanism of cholera Toxin?

  • â produce the symptoms of cholera.
  • a-b type adp -ribosylating Toxin

sub unit a: adp-ribosylating Activity.

 sub unit b: bind to a gmi ganglioxide Receptor.

  • catalyze the adp ribosylation Of the g protein
  • camp
  • secretion of electrolyte & Water
  • massive watery diarrhea without inflammation (20-30l/d)
  • dehydration & electrolyr imbalances Shock,acidosis,death.
  • please give interpretation to Culture medium?

it supports containing appropriate nutrients Artifitially made for growth of bacteria (or) fungi. I.E, liquid,semisolid,solid Medium

  1. nutrients
  2. ph
  3. temperature
  4. aeration
  5. ionic strength
  6. osmotic pressure
  7. what are the four stages of Clinical findings of hiv infection ?

four stages

stage i : primary

  • short,six weeks after infection
  • no symptoms
  • infected person can infecter Other

stage ii : asymptomatic

  • lasts for average of 10 years
  • hiv ab are detected in the Blood

stage iii: Symptomatic

  • symptoms are mild
  • immune system dterites

stage iv : hiv --- Aids

  • immune system weekens
  • oppprtunistic infection - pneumocystosis 4 Malignancies -- karposis sarcoma

  bacterial --- tuberculsis,strep Pneumonia

  viral -------- herpes,influenza

parasite -----pneumocytis carini pneumonia (pcp)

  fungi -------candida,cryptococcus.

  1. please explain Transformation?

direct uptake of donor dna by recipient cells Depends on their competence

*competence: the ability to take up dna from Environment

 *some species have competence in Nature

*some can enter the competent state by Treatment

  1. how is tetanus acquired? What is Its pathogenesis?

â tetanus is acquired through exposure to the Spores of the bacterium. Clostridium tetani which are universally present in the Soil.The disease is caused by the action of a potent neuro toxin produced during The growth of the bacteria in dead tissues, e.G in dirty wounds or in the Umblicus following non steile delivery.


  1. infection of wound by spores
  2. germination of spores ti bacilli
  3. bacilli produce Toxin(tetenospasmin)
  4. toxins affect cns and inhibit inhibitory Mediators which responsible for relaxation of muscles after Contraction
  5. so contraction prolongs
  6. what is the difference between Sterilization and disinfection?


 completely destroys or removes all microbial Life, including spores.

 by physical or chemical process


  killing, or removal of microorganisms that May cause disease

  1. which virus can be transmited by Sexual contact?



â â â â â â â  *hepatitis b

  1. describe the morphological and Cultural characteristics of mycobacterium tuberculosis?

â morphology:

 thin rods,acid-fast bacilli.

â cultural:

 * obligate aerobic

* nutition are high,lowerstein-jensen Medium

 *it grows very slow with a generation time of 18 hours,colony,3-4 weeks.

 *the rough colonies Granular,dull-yellow,dry.

  1. describe the infection sources and Transmission routes of hbv?

infection source:

  1) patients with hepatitis b

 2) asymptomatic hbs ag carrier (asc)

transmission routes:

 1) via infected blood (or) blod Products

  2) vertical transmission

  3) others(tightly contact & Sex).

  1. pleaes explain spore of Bacterium?
  2. formed in response to adverse Conditions
  3. sporulation occurs when nutrients are Depleted
  4. inside the cell, mother cell Autolysis
  5. contains baterial dna, a small amount of Cytoplasm, cell membrane, peptidoglycan, very little water, a thick Coat
  6. a thick, keratinlike coat: responsible for the Remarkable resistance of the spore to heat, dehydration, radiation and Chemicals.
  7. is a resting cell, the spore has no metabolic Activity and remain dormant for many years
  8. when returned to favorable environment, the Spore germinates to produce a single vegetative cell
  • sterilization cannot be achieved by Boiling
  •  patients can be infected by spore-forming Organisms
  • describe the antigenic shift and Antigenic drift of influenza virus?

antigenic shift:

*reassortment of genes is a common feature of Influenza virus a, but not b or c

*when two different "a" viruses infect the same Cell, their rna segments can become mixedâ  during replication

*new viruses produced in this way may survive Due to a selective advantage within the population

antigenic drift:

*constant mutations in the rna of influenza Virus which lead to polypeptide mutations

*changes are less dramatic than those induced By shift

*if these mutations affect ha or na they may Cause local epidemics.

  1. what are the pathogenic substances Produced by spteptococcus aureus?
  2. â â â coagulate and clumping Factor

  cause plasma to clot

  initiate fibrin polymerization deposist

  fibrin on the surface of bacteria

 s.Aurues is distinguished from the others Primarily by coagulate production

  1. exotoxins
  2. toxic shock syndrome toxin
  3. enterotoxins
  4. what disease can caused by Salmonella

  typhoid fever

  1. what are the pathogenic substances Produced by meningococcus?
  2.  localized infections

in men : urethritis with dysuria and purulent Discharge

in women: purulent vaginal discharge Intermenstrual bleeding ascending infection of the uterine tube ectopic Pregnancy (or) infertility.

  1. disseminated infection

- arthritis

- pustules

  1. new born infants

- purulent conjunctivitis

  1. which toxins are Neurotoxin?

batulinum toxin


tetanus toxin

nitric oxide






arsenic mercury

  1. describe pathogenesis of treponema Pallidum.

- nature infection with t.Pallidum occurs only In human beings

-habitat:  The human skin (or) mucous membrane


â intimate contact(sexual contact),pregnant Women to fetus via placenta.

- produce no important toxins (or) Enzymes.

- diseases:- syphilis (std)

acquire syphilis (venereal syphilis) - sexual Contact

primary syphilis - nontenderuter

secondary lession - maculopapular Vash

tertiary syphilis -gumma

congenitial syphilis

  1. which virus is associated with Nasopharyngeal carcinoma,cervical cancer?

  nasopharyngeal --- epstein barr virus, Cmv

 cervical cancer ----hpv

  1. which virus cause vertical Transmission?

from mother to off-spring through Placenta,delivery and suckling, such as hbv,hiv & hsv

  1. which viruses are the cause of Congenital malformation?


  1. what shape of rabies virus, Describe the transmission routes of rabies virus,how to prevent rabies.?
  2. shape: bullet
  3. transmission Routes:

 by bitting or scratching of animals ( through Saliva)

airborne ( bats )

  • prevention :

  handling the bitting site-complete washing With solvent water usage of disinfected

  anti virussera

  usage of vaccine

  1. what are the asepsis and Disinfection?


absence of pathogenic microbes

the technique that prevents bacteria from going To the body ( or ) other objects.


 killing (or) removal of microorganisms that May cause diasease

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