Influenza specific agents

Gangliosides are receptors for specific agents, such as cholera toxin and influenza virus. Cholera toxin binds to ganglioside GMl, whereas influenza virus recognizes the sialic acid portion of certain gangliosides. The influenza virus then cleaves the gangliosides as part of its entry process into cells. 

Viruses are small infectious agents composed of a nucleic acid genome (DNA or RNA) encased by structural proteins and in some cases a lipid envelope. They are the causative agents of a number of human infectious diseases, the most important for public health today being acquired immunodeficiency syndrome (AIDS), hepatitis, influenza, measles, and vituses causing diarrhoea (e.g., rotavirus). In addition, certain viruses contribute to the development of cancer. Antiviral drugs inhibit viral replication by specifically targeting viral enzymes or functions and are used to treat specific virus-associated diseases. 

It may be possible to increase the utility of our resources to treat influenza virus infection through combinations of antiviral agents with different modes of action (discussed in Cinatl et al. 2007a De Clercq and Neyts 2007). The sialidase inhibitors, for example, may be able to be used in conjunction with the adamantane-based M2 ion channel inhibitors (Govorkova et al. 2004 Ilyushina et al. 2006), with Ribavirin (Smee et al. 2002) or with non-influenza virus specific therapeutics such as anti-inflammatory drugs (Carter 2007). Combination therapy may also reduce the potential of resistance development (Ilyushina et al. 2006). 

Amantadine (C) specifically affects the replication of influenza A (RNA) viruses, the causative agent of true influenza. These viruses are endocytosed into the cell. Release of viral DNA requires protons from the acidic content of endosomes to penetrate the virus. Presumably, amantadine blocks a channel protein in the viral coat that permits influx of protons thus, uncoating is prevented. Moreover, amantadine inhibits viral maturation. The drug is also used prophylactically and, if possible, must be taken before the outoreak of symptoms. It also is an antiparkinsonian... 

This chapter describes the basic characteristics of viruses and the relatively limited number of drugs that can act selectively as antiviral agents. Methods of preventing viral infections (antiviral vaccines) are also briefly discussed. Finally, the current methods of treating a specific viral-induced disease—AIDS—are presented. Rehabilitation specialists often treat patients who are in the active stages of a viral infection, as well as those suffering from the sequelae of viral disorders, such as gastroenteritis, encephalitis, and influenza. Hence, the pharmacotherapeutic treatment and prophylaxis of viral infections should concern physical therapists and occupational therapists. 

The primary target for both agents is the M2 protein within the viral membrane this target incurs both specificity against influenza A (since influenza B contains a different protein in its membrane) and a mutation-prone site, causing the rapid development of resistance in up to 50% of treated... 

Both agents specifically inhibit the replication of influenza A viruses. Rimantadine is 4-10 times more active than amantadine. 

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