Biology 42 – Human Biology (Spring 2007)
[ Students and professors, please read. ]
SARS is caused by a previously unknown, newly described strain of coronavirus called SARS-associated coronavirus (SARS-CoV). “It is possible that other infectious agents might have a role in some cases of SARS” (3). Previously identified coronaviruses are a family of viruses that are a common cause of mild to moderate upper respiratory illnesses in humans, including the common cold, and “are associated with respiratory, gastrointestinal, liver and neurologic disease in animals” (3). “Until now, these viruses have never been particularly virulent in humans” (5). When viewed under a microscope, coronaviruses look like they have spiky crowns or halos. “Using high-powered microscopes, blood tests, and other standard laboratory techniques” (2), “NIAID-supported scientists” (4) at “the University of Hong Kong were the first to announce (on March 21, 2003) the discovery of a new coronavirus as the possible cause of SARS, after successfully cultivating it from tissue samples” (2). “Initially, electron microscopic examination in Hong Kong and Germany found viral particles with structures suggesting paramyxovirus in respiratory secretions of SARS patients; subsequently, in Canada, electron microscopic examination found viral particles with structures suggestive of metapneumovirus (a subtype of paramyxovirus) in respiratory secretions. Chinese researchers also reported that a chlamydia-like disease may be behind SARS. The Pasteur Institute in Paris identified coronavirus in samples taken from six patients. The CDC, however, noted viral particles in affected tissue (finding a virus in tissue rather than secretions suggests that it is actually pathogenic rather than an incidental finding). Upon electron microscopy, these tissue viral inclusions resembled coronaviruses, and comparison of viral genetic material obtained by PCR with existing genetic libraries suggested that the virus was a previously unrecognized coronavirus. …On April 7, 2003, WHO announced that it was generally agreed that a newly identified coronavirus is the major causative agent of SARS, and that the significance of a human metapneumovirus (hMPV) in SARS remains unclear and would continue to be studied. This was followed by an announcement by WHO on April 16” (1) that “scientists at Erasmus University in Rotterdam, the Netherlands demonstrated that the SARS coronavirus fulfilled Koch’s postulates thereby confirming it as the causative agent. In the experiments, macaques (MS: monkeys) infected with the virus developed the same symptoms as human SARS victims” (2). “Continued study is underway to test the hypothesis that co-infection with other organisms such as human metapneumovirus may also play a role” (1).
Most of the above consists of direct quotes from the following sources: