Viruses General Introduction To VIRAL DISEASES Diagnosis Causative Agents

Viruses General Introduction To VIRAL DISEASES Diagnosis

Viruses Definition

• Viruses are obligate intracellular parasites which consist of a nucleic acid surrounded by one or more proteins.
• They can be active, metabolize and replicate only in­side a living cell.

Viruses Definition and types

Virusoids

• are nucleic acids dependent on helper vi­rus.

Viroids

• are double-stranded RNAs.

Prions

• are abnormal protein molecules which can spread and change the structure of other proteins. They cause diseases like Creutzfeldt-Jakob disease and Mad-cow disease.

Resistance to viral infections

• is by physical pro­tection by skin and mucus secretions which wash off the virus.
• Other means of resistance are Interferons – IFN al­pha or beta, IFN y, virus specific antibody, HLA class II, class I, T lymphocytes, antibody type IgM, IgG, and IgA.

Diagnosis:

• · Serology, Viral isolation in tissue culture, antivi­ral antibodies, ELISA, Western blot.
• – Polio virus; Coxsackie virus Hepatitis E virus Rubella virus
• Dengue, Hepatitis C virus SARS
• Rabies
• Parainfluenza; Respiratory syncytial; Mumps;
• Rubeola or measles. Influenza A, B & C HIV virus
• Caliciviridae Togaviridae Flaviridae Coronaviridae Rhabdoviridae Pa ra myxovi ridae
• Orthomyxoviridae Retroviridae

Viruses Types

• Hepadnaviridae
• Adenoviridae
• Herpesviridae
• Hepatitis B Adenoviruses
• Herpes simplex;
• Varicella zoster;
• Epstein-Barr;
• Cytomegalovirus Small pox or variola

Viral Disease Causative agents

Influenza A & B

• 1. Influenza A & B

Respiratory syncytial virus (RSV)

Respiratory syncytial virus (RSV)

• 2. Respiratory syncytial virus (RSV)

Varicella

• 3. Varicella

Herpes simplex

• 4. Herpes simplex

Herpes zoster

• 5. Herpes zoster

hepatitis B

• 6. Chronic hepatitis B

TREATEMENT OF VIRAL DISEASE

• Ribavirin Acyclovir
• Acyclovir – Topical, Oral, IV
• Acyclovir
• IFN alpha 2b, Lamivudine, Adefovir dipivoxll
• IFN alpha- 2a or 2b, Pegylated IFN alpha 2a,2b and Ribavirin IFN alpha 2a or alpha 2b

Immunization

• Viral vaccines like polio virus, measles, smallpox, HBV, Rubella, Mumps, and Chickenpox.