Q1. Viruses are distinguished and classified according to..

1_ nature of nucleic acid in the virion.

 - Either DNa or RN

-single stranded or double stranded

-segmented or non segmente

-linear or circular

-positive or negative sense

 

2_symmetry of protein she

. Single or double protein shell

Icosahedra

.filamentou

 

3_presence or absence of lipid membra

 

Either enveloped or non envelope

 

4_demensions of virion and caps

_Isometric or not.

_size and shape of the caps

d idd nesl.ll  d A.shape of the capsid

 

Question 2

Lytic cycle..

Reproductive cycle of virus that result in the destruction of infected cell and its membranes

Events.

. 1 attachment.. Virua attach its tail to infected cell

2.digestion.. Virus produce enzyme lysozyme that digest cell wall of infected cell

3.injection

Virus contract and inject its DNA into host while protein coat and tail remain outside

4.taking control.. Virus take control of biosynthetic machinery of host cell and synthesize its own protein and dna

5.multiplication.. Virus multiply amd increase in number. That exert pressure on cell wall of infected cell

6. Rupture. Finally host cell rupture and viruses and released and they affect new cells

 

Lysogenic cycle.

lysogenic cycle is a method by which a virus can replicate its DNA using a host cell machinery without causing distraction of cell

 

Stages..

1 entry into cell. Viral genome enters cell. 

2) Viral genome integrates into Host cell genome

3) Host cell DNA Polymerase copies viral chromosomes

4) cell divides, and virus chromosomes are transmitted to cell's daughter cells

5) At any moment when the virus is activated lytic cycle starts

 

Question 3

Antigenic shift.. is a major change in an influenza A virus that result in new HA virus and NA proteins in influenza viruses that infect humans. Shift can produce many new influenza A subtype in human birds and pigeons

 

Antigenic drift

Antigenic drift is the natural process involving accumulation of a series of minor genetic mutations that produce alteration in immune system

 

Question #4

1.Conjugation is the transfer of circular DNA called plasmids through cell to cell contact. 

2.Transformation is the uptake of 'free' DNA from the environment.

3 transduction. Transduction is the process by which foreign DNA is introduced into a cell by a virus or viral vector.

 

In addition to these process, bacteria can change by environmental factors or it can also evolve new gene by genetic mutations

 

Question #5

Exoenzymes of staphylococci..

Nuclease and protease inactive and cleave immune defense such as antimicrobial peptide and complement factor.

Coagulase. Convert fibrinogen to. Fibrin and clot plasme

 

Hyaluronidase.. Cleave hyaluronic acid and promotes dissemination of bacteria

Streptokinase.. That digest clot

 

Exoenzymes increase pathogenicity of bacteria by facilitating its invasion by produce hyaluronidase.. Preventing it from immune defense by producing. Nucleases proteases. coagulase that clotting plasma. And increasing its number.

 

Question# 6

The bacterium uses several ways to become more pathogenic which involves different virulance factors. These includes 

~elaboration of pili

~Opa protein expression 

~ lipooligosaccharide expression 

~por protein expression

~IgA protease

This makes the bacterium survive better inside the human host cells.

Question #7

1.Clostridium botulinum.. that produces dangerous toxins called botulinum toxins under low-oxygen conditions that prevent release of exitatory neurotransmitter acetylcholine from nerve endings. Botulinum toxins are one of the most lethal substances known. Botulinum toxins block nerve functions and can lead to respiratory and muscular paralysis. 

 

2. Clostridium difficile produce two exotoxins: toxin A and toxin B These toxins disrupt the cytoskeletal structure and the tight junctions of target cells causingcell death 

 

3. Clostridium tetani. Produce tetanolysin, which causes local tissue destruction and tetanospasmin, which causes tetanus. By inhibiting release of inhibitory neurotransmitter from nerves

 

4.Clostridium perfringens produce alpha toxin that produce phospholipase C . That activate pathways that cuz cell death and cause gas gangrene and myonecrosis 

. Also cause. food poisoning

 

Question #8

Listeria monocytogenes is the species of pathogenic bacteria that causes. _infection.. listeriosis. 

_It is a facultative anaerobic bacteria 

_capable of surviving in the presence or absence of oxygen.

 

Listeria avoid humoral immune system by creating intracellular niches that prevents it to be recognized by immune system.. Hence it modulate host signaling pathway needing for immune activation thus favors a successful infection and prevent phagocytosis of bacteria

 

Question 9

Borrelia hermsii has a unique process of DNA rearrangement that allows them to periodically change the molecules on their outer surface. This process is called antigenic variation, which allows the bacteria to evade the host immune system and cause relapsing episodes of fever and other symptoms.

 

Borrelia infection is transmitted to humans by infected lice or ticks specially ornithodoros genus ticks

 

Question 10:

Orthomyxoviruses are single stranded RNA viruses that are spherical in shape and can cause influenza

 

Question #11

 it shows five stages of disease inside the host that are :

1)incubation

2)prodrome

3)acute neurological period

4)coma

5)death (rarely recovery)

 

Lyssa includes group of viruses like rabies which transmits from infected animal like cats, dogs ,wolves etc

 

It is almost fatal if left untreated.

 

Question 12

HIV invades CD4 cells that are major part of adaptive immune system. Inside CD4 cells(also known as helper T cells) these viral particles divide and produce more and more offsprings. As a result the CD4 cells bursts and higher amount of HIV cells release to infect other CD4 cells.

 

It spreads when an infected blood , semen or vaginal fluids enter the body. These fluids containing the Virus infect the human body.

 

Symptoms:

It can be asymptomatic but as the immunity lowers by this virus, other infections occur very rapidly and person can feel 

High fever, sore throat and other related symptoms.

 

Question 13:

Oncogenic virus is a virus that is involved in causing cancer inside the body of host.

Examples of oncogenic viruses are:

1)HBV- can cause hepatocellular carcinoma

2)EBV- can cause Burkitt's lymphoma

3) HPV- oral , cervical cancer

 

Question 14

Sign and symptoms of pox virus include:

- Fever

-Headache

-muscle aches

-swollen lymph nodes

-chills etc

 

List of pox virsus that can infect human beings are

Monkeypox virus, orf virus , molluscum contagiosum.

 

Small pox is most deadly for human beings

 

Question#15

West Nile Virus tranmits by mosquito bite. 

When Mosquitos bite infected birds then become infected then these infected mosquitos bite humans and animals and transfers West Nile Virus.

 

Symptoms include:

Very high fever

Stiffness of neck

Weakness of mucles

Convulsions 

Paralysis and

Coma .

 

Treatment:

There is no specific treatment available for this virus. Patient must be hospitalized and provide the supportive care like I.V fluids , medications to relieve pain and other nursing care.