Selectively inhibit viral replication without affecting the normal functions of the host cell. They inhibit the viral nucleic acid replication process. 

Remember, there are no broad-specturm antivirals 

Alters cellular nucleotide pools, inhibits viral RNA synthesis and may cause lethal RNA mutation. 

It is used for severe RSV infections and in combination with (interferon) IFV-alpha for chronic hepatitis C virus (HCV) infections 

prevent DNA chain elongation after recognition of base pairing.

These drugs are activated by phosphorylation by cellular or viral kinases. 

Examples include many herpes simplex, VZV, cytomeglovirus, and HIV antivirals 

Inhibit thymine biosynthesis or replace thymidine in DNA which leads to misreading of the DNA and mutations.

Examples include: Idoxuridine, Trifluorothymidine, fluorouriacil. 

Saquinavir, indinavir, ritonavir, nelfinavir, amprenavir 

These inhibit the action of HIV protease; used in combination with AZT and a second nucloside analog as "cocktail" therapy in HIV 

oseltamivir and zanamivir 

They inhibit the neuraminidase (essential for viral attachment) of influenza A and B viruses; they may be used for prophylaxis as well as treatment. 

A mRNA Inhibitor. A synthetic oligonucleotide complementary to a sequence in CMV RNA (an antisense compound). It prevents transcription of early CMV genes. 

It is approved for intravitreal (inside the eye) therapy of CMV retinitis after other therapies have failed .

Are host-coded proteins or glycoproteins produced in and secreted from virus-infected cells in response to viral infection 

They are host specific. 

Three groups recognized: IFN- alpha, beta, and gamma 

Involves: 

1. Virus isolation

2. Direct demonstration of the virus, viral nucleic acid, or antigens in clinical specimens

3. Serologic testing of viral specific antibodies 

Identifies virus replication in susceptible cells . Embryonated eggs or animal hosts often used. 

a. in live infected tissue culture cells, replication may be detected by observing a cytopathogenic effect, polykaryocyte formation or hemadsorption. 

b. fixed infected tissue culture cells. Replication may be detected by observing characteristic inclusion bodies (in nucleus or cytoplasm)...deposit of protein or carbs left behind.  

C. In embryonated egg, replication is detected by pock formation. In animals, by the development of clinical symptoms 

samples include tissue biopsies, smears, CSFs, urine, etc

Examples of assays: immunohistochemical staining, nucleic acid hybridization, amplification methods

Detect antigens such as rotavirus and HAV 

They use specific viral Abs and radioimmunoassay or enzyme-linked immunosorbent assay. 

These assays are highly sensitive and speficic 

Used to determine the titer of specific antiviral Abs. 

Paired blood samples are taken. At least a 4fold increase in titer between the samples must be present to indicate a current infection. 

based on the fact certain Abs will neutralize the cytopathic effect of the virus.

If cytopathic effect neutralized by a particular serum: the sample is positive and Abs in the serum were effective against the virus and visaversa. 

based on the idea that serum with inhibit viral agglutination of erythrocytes. 

Tests can only be done with viruses that have hemagglutinins on their surface (influenza, measles) 

injection of human plasma or gamma-globulin fractions from immune individuals 

Used to prevent: rubella, measles, mumps, HAV, HBV, rabies, and Varicella-zoster virus (VZV)

Plasmid DNA expressing vectors that elicit both humoral nad cell-mediated immune responses. 

Used for HIV and influenza 

Sequences of virion receptors that have been 

Advantages and disadvantages are the same for killed vaccines 

Ex: HBV, HEV (hep. E virus) , HPV (human papillomavirus)

purified proteins (viral receptors) obtained from virions. 

Advantages and disadvantages are the same as for killed vaccines

Ex: adenovirus 

Prepared by heat or chemical inactivation 

Advantage: easily combined into vaccines. Doesn't elicit an immune response

Disadvantage: lack of development of secretory IgA. You need boosters; poor cell-mediated response

Examples: poliovirus, rabies, influenza, HAV

Attenuated strains that are avirulent

Advantage: admin. in single dose; induces wide spectrum of Abs and cytotoxic cells 

Disadvantages: limited shelf life, possible reversion to virulence, possible production of persistent infection

Ex: measles. mumps, rubella, chickenpox, rotavirus, yellow fever, some adenovirus strains

Involves cytotoxic T lymps., Ab-dependent cell-mediated cytotoxicity, NKcells and activated macrophages. 

This is the most important defense mechanism against noncytolytic infection (alteration of the virus-infected cell membrane)

Part of the Humoral Immune system: inhibit the ability of a virus to replicate by inhibiting viral attachment, penetration, uncoating, or all 3 processes .

Lesions may also be induced in the viral envelope with the aid of a complement 

Process: 

1. ds viral RNA interacts with host ribonuclease DICER

2. Forms short interfering RNAs (siRNAs) which interact with argonaute proteins to form RICS (RNA-inducing silencing complexes)

3. RISC binds to viral mRNA and inhibits viral gene expression 

1. Innate immunity : anatomical and chemical barriers 

2. Cellular resistance

3. Inflammation: creates low pH, elevated temp. 

4. IFN: inhibits viral replication; species specific; the first viral induced defense mech.