THREAT TO THE FUTURE
Fears that the SARS virus could pose a threat to humans for many years to come,have heightened.
Scientists have compared samples of SARS virus from Singapore with samples from other countries where it has struck and found that the main components of the virus have remained unchanged as infection has spread across different countries.
They say the finding suggest that it is well adapted to resisting attack by the human immune system and so does not need to evolve rapidly.But the stability of the virus also means that any viccine that is developed may remain effective against SARS for a long period.
The SARS virus has been identified as a new member of the corona family.It has been dubbed SARS-CoV.Usually human corona viruses have a high rate of genetic mutation which can lead to new strains.
NO HOPE FOR VACCINE NOW
Reports from the LANCET medical journal point to the possibility of developing a SARS vaccine are still remote.A group of researchers led by Dr. Edison Liu,from Singapore's Genome Institute,who studied the genetic make up of cultured SARS viruses from five different sources ,found only a handful of mutation differences between the samples and it was thought these probably resulted from the virus adaptting to laboratory
Normally.if the human immune system is good at fighting a viral infection,that usually produces changes over time in the genes of that particular virus.But this is not happening in the SARS coronavirus-suggesting the human immune system is not very effective at producing defences to it.
The World Health Organization(WHO)however says it is too early to tell whether significant mutations are occurring.Other scientists comment that if the virus is relatively stable,that may make it easier to design a vaccine.They also warn that vaccines against coronavirus diseases have often been unsuccessful.
Another study-concludes that much of the lung damage associated with SARS is in fact caused by the body's own response to infection.Researchers from University of Hong Kong found a common pattern of illness among 75 patients who were admitted to hospital following an outbreak of SARS at Amoy Garden ,Hong Kong high rise housing estate.
For the first week after admission,symptoms gradually improved,but a deterioration set in during the second week of the hospital stay.About 85% of the patients developed recurrent fever after nine days.This delayed deterioration suggests that damage is being inflicted on the lungs not by the contiunued spread of the virus ,but by an overblown immune response.