Influenza
Influenza is a contagious and potentially fatal disease. It is caused by a virus which infects the respiratory tract. The incubation period is typically two days, with the patient being infective for a day before experiencing symptoms and up to 5 days after first experiencing symptoms. Infection usually lasts about a week and symptoms include a high fever, headache, extreme tiredness, a dry cough, sore throat, and a runny or blocked nose.
While most people recover from influenza within one or two weeks without medical treatment, the disease can pose a serious risk in the very young and the elderly.
The highest rate of infection and hospitalisation is for people older than 65 and the second highest rate is for children younger than five. People with medical conditions such as lung disease, diabetes, cancer, kidney or heart problems can also be seriously affected, and in these cases influenza infection can lead to severe complications of the underlying diseases, pneumonia or even death.
Influenza spreads rapidly around the world in seasonal epidemics and each year annual epidemics affect between 5 - 15% of the population. According to the Centers for Disease Control and Prevention (CDC), in the U.S. alone, more than 200,000 people are hospitalised on average every year because of influenza complications and about 36,000 people will die because of the disease. The World Health Organization (WHO) estimates that annual influenza epidemics around the world cause between 3 and 5 million cases of severe illness and between 250,000 and 500,000 deaths every year. In 2004, influenza and pneumonia was the fourth leading cause of death in Australia (Australian Bureau of Statistics, 2004).
In the last century, three global influenza pandemics occurred when the influenza A virus underwent major genetic changes. The most infamous pandemic, the Spanish Flu in 1918-1919, killed 500,000 people in the U.S. and between 50 and 100 million worldwide, nearly half of whom were between 20 - 40 years old. Notably, pandemic influenza appears to have a greater impact on healthy young adults than seasonal influenza, which tends to affect the young and old. More recently, there have been concerns of another possible pandemic as a result of a new influenza subtypes, being widely distributed globally.
Biota's solution
Influenza viruses are divided into groups, with A and B being of most concern to humans. All influenza viruses have two different spike-like protein components on their surface, called haemagglutinin (H) and neuraminidase (N), which are both associated with attachment and release mechanisms the virus uses to infect and subsequently shed from the lung cells.
Through droplets spread by coughing and sneezing, influenza infects the respiratory tract directly, replicates in the cells lining the airways of the lungs and is shed from the lungs.
Neuraminidase is essential for the replication of all influenza viruses. It is an enzyme which breaks down bonds that are holding new viruses to an infected cell, allowing viruses to release and infect other cells; this extends the influenza infection. Neuraminidase inhibitors block this activity, preventing the release of new viruses from infected cells and stopping the infection from spreading.
Biota has developed its neuraminidase inhibitor zanamivir (Relenza) to be delivered via an inhaler directly to the site of action, in the lung. Relenza provides a rapid antiviral action and reduced systemic side effects.
Biota's second generation influenza products are long-acting neuraminidase inhibitors (LANIs). Also inhaled, LANIs provide a longer period of action which allows them to be administered only once a week, instead of twice daily as is the case with current products.
LANI's high potency and reduced frequency of administration offers a practical response to the reduced storage bulk needed for pandemic stockpiling. Biota has a joint venture with Japanese based Daiichi Sankyo for the development of LANIs.