Flu - On the horizon

One of the key features of influenzaA viral infection affecting the respiratory system., or 'fluA viral infection affecting the respiratory system.', virusesMicrobes that are only able to multiply within living cells. is their ability to mutate and change progressively over time. The result is that they gradually become able to escape detection by the body's immune systemThe organs specialised to fight infection., as well as developing resistanceThe ability of a microbe, such as a type of bacteria, to resist the effects of antibiotics or other drugs. to available vaccines and antiviralA substance that acts against viruses, for example and antiviral drug. medications.

Scientists are continually trying to find ways to keep up with these changes.  The investigation of new vaccines and antiviralA substance that acts against viruses, for example and antiviral drug. medications are two important aspects of this ongoing research.

New vaccines

What is the background?

Every year, before the onset of the fluA viral infection affecting the respiratory system. season in temperate climates, the World Health Organization recommends three strains of influenzaA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells. to be targeted by this year's fluA viral infection affecting the respiratory system. vaccine. However, after these recommendations are made, the influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells. continue to undergo changes in their antigens, which can make the vaccine less effective.[1]

This highlights the need for new vaccines, which will retain their effectiveness, despite ongoing changes in the influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells..[1]

How do the vaccines work?

Several new approaches to vaccines are under development.

The ideal goal would be to develop a vaccine that offers protection against all the strains of influenzaA viral infection affecting the respiratory system. - a universal vaccine. With this in mind, one type of vaccine under investigation, called the 'VP22/NP plasmid DNAThe building blocks of the genes in almost all living organisms - spelt out in full as deoxyribonucleic acid. vaccine', has been shown to protect against different subtypes of the influenzaA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells. in mice. This suggests that the development of a 'broad spectrumHaving a wide range of activity. For example, broad-spectrum antibiotics are effective against a wide range of bacteria.' vaccine may be possible - in other words, a single vaccine that can protect against many different types of influenzaA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells..[1,2]

Current influenzaA viral infection affecting the respiratory system. vaccines target proteins in the virusA microbe that is only able to multiply within living cells. called antigens. Unfortunately, as virusesMicrobes that are only able to multiply within living cells. undergo changes in their genes over time (called mutations), their antigens also change. This is the same way that the virusA microbe that is only able to multiply within living cells. manages to escape detection by the immune systemThe organs specialised to fight infection.. See How flu viruses beat the immune system

These changes can mean that the vaccine is no longer effective against the virusA microbe that is only able to multiply within living cells., and this is why scientists need to bring out new vaccines every year: because the older vaccines become less effective as time passes However, not all viral proteins change - some parts of the virusA microbe that is only able to multiply within living cells. remain the same even though the rest of the virusA microbe that is only able to multiply within living cells. mutates and alters over the years. Scientists are now working on vaccines that will target the proteins that stay the same. If they succeed, such a vaccine should be much more effective. This is because even though the virusA microbe that is only able to multiply within living cells. will continue to mutate and some of its elements will change, the vaccine will still be effective against it.

Intranasal vaccines contain a virusA microbe that is only able to multiply within living cells. that is still alive although weakened (attenuatedA microbe that has been treated so as to be less able to cause disease. Attenuated bacteria or viruses are used in many immunisations, to stimulate the body's immune system against a disease without actually causing that disease.). As such, the virusA microbe that is only able to multiply within living cells. is still capable of infecting cells and so can trigger the immune systemThe organs specialised to fight infection. more effectively. It may also be able to protect against influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells. of different subtypes.[1]

Who is it for?

Older people and those whose immune systems are impaired to some degree would benefit most from these new influenzaA viral infection affecting the respiratory system. vaccines, which offer greater protection against more strains of the influenzaA viral infection affecting the respiratory system. virusA microbe that is only able to multiply within living cells..[2]

What stage of development has been reached?

These vaccines are all at varying stages of development. For example, the VP22/NP plasmid DNAThe building blocks of the genes in almost all living organisms - spelt out in full as deoxyribonucleic acid. vaccine is still in a preclinicalA term that may be used to describe a period in the disease process before symptoms appear, or a study conducted in animals. stage of development, but it has shown some promising results in mice. Meanwhile, live attenuatedA microbe that has been treated so as to be less able to cause disease. Attenuated bacteria or viruses are used in many immunisations, to stimulate the body's immune system against a disease without actually causing that disease. intranasalWithin the nose. vaccines are already available for use in some, although not all, countries.[1]

New antiviral drugs

What are they?

The currently available antiviralA substance that acts against viruses, for example and antiviral drug. drugs that target fluA viral infection affecting the respiratory system. are often not as effective as they could be. The reason for this is that influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells. frequently become resistantA microbe, such as a type of bacteria, that is able to resist the effects of antibiotics or other drugs. to the drugs. This suggests that, sooner or later, influenzaA viral infection affecting the respiratory system. virusesMicrobes that are only able to multiply within living cells. may no longer be susceptible to any drug that directly targets the virusA microbe that is only able to multiply within living cells.. As such, new approaches are needed.[3]

When any virusA microbe that is only able to multiply within living cells. infects a cellThe basic unit of all living organisms., it uses the cellThe basic unit of all living organisms.'s own 'machinery' to make more copies of itself - in other words, to replicate. Blocking these mechanisms may therefore prevent viral replicationThe process by which DNA makes copies of itself when a cell divides.. One such strategy involves blocking the cellThe basic unit of all living organisms.-signalling pathways that are triggered by the virusA microbe that is only able to multiply within living cells.. The virusA microbe that is only able to multiply within living cells. cannot bypass this blockage and, as such, should not be able to become resistantA microbe, such as a type of bacteria, that is able to resist the effects of antibiotics or other drugs. to this type of antiviralA substance that acts against viruses, for example and antiviral drug. drug.[3]

How do they work?

Blocking the intracellular signalling pathways needed for viral replicationThe process by which DNA makes copies of itself when a cell divides. seems to be the most promising goal for new antiviralA substance that acts against viruses, for example and antiviral drug. medications. It has been shown that this can reduce viral replicationThe process by which DNA makes copies of itself when a cell divides., without causing side-effects or bringing about drug resistanceThe ability of a microbe, such as a type of bacteria, to resist the effects of antibiotics or other drugs..[3]

Who are they for?

Again, antiviralA substance that acts against viruses, for example and antiviral drug. drugs are likely to be most helpful for those who are at higher risk of developing the complications of influenzaA viral infection affecting the respiratory system. - for example, older people and anyone with underlying chronicA disease of long duration generally involving slow changes. medical conditions.

What stage of development has been reached?

Although these newer strategies are still in an early phase of development and have not yet been tested in humans, they seem to be very promising, especially in terms of preventing viral resistanceThe ability of a microbe, such as a type of bacteria, to resist the effects of antibiotics or other drugs..[3]

Several drugs with this mechanism are already under investigation for other purposes; it may therefore be possible for a pharmaceutical company to start developing one of these existing drugs for an additional antiviralA substance that acts against viruses, for example and antiviral drug. use, rather than 'starting from scratch'.[3]

References: 
  1. Carrat F and Flahault A. Influenza vaccine: the challenge of antigenic drift. Vaccine. 2007;25:6852-62.
  2. Palache B. New vaccine approaches for seasonal and pandemicAn outbreak of infection that affects numerous people in different countries. influenzaA viral infection affecting the respiratory system.. Vaccine. 2008;26:6232-6.
  3. Ludwig S. Targeting cellThe basic unit of all living organisms. signalling pathways to fight the fluA viral infection affecting the respiratory system.: towards a paradigm change in anti-influenzaA viral infection affecting the respiratory system. therapy. Journal of Antimicrobial Chemotherapy. 2009;64:1-4