Introduction
The paper A Novel Coronavirus Associated with Severe Acute Respiratory Syndrome by Ksiazek et al. is a very interesting paper that could provide a new direction in understanding the causative organisms of SARS and similar diseases. It is also a good starting point for researchers who are working on viral recombinant behavior and cell mutations seen in different viruses. The authors claim that they could have isolated a Coronavirus, whose name they propose as Urbani SARS-associated Coronavirus that could be involved in the outbreak of SARS.

Analysis
The paper presents a well developed approach that has been used to isolate and study the virus under question. The techniques used by the researchers are commendable and the troubles to which they have put themselves to, in order to study a virus that had created havoc among the medical fraternity for its severely infectious nature, is highly commendable. In addition, the paper is a very thought provoking one although it is not conclusive. Some of the comparative points of the research paper are:

Strong points

1. Good preparatory procedures

The researchers have taken good preparatory procedures to study the virus. The clinical safety standards and the research etiquettes that they have meticulously followed in their research process can be considered as a very good example of responsible handling of dangerous pathogens.

2. Comparisons were conducted with a wide variety of viral RNAs (Ksiazek et al., pp2)

Another highlight of the research is that the authors have conducted the comparison of the virus in question with a wide variety of viral RNAs to conclusively rule out any similarity. This has gone a long way in providing the rather surprising finding that Coronaviruses found in humans could be involved in the SARS epidemic

3. A phylogenetic tree was constructed to isolate the strain of the virus

Care was taken to create a phylogenetic tree to ensure that the similarities of the viral genes could be used for further study. This will also help in future research when the strains of the virus have to be studied for its genetic similarity with other strains.

4. The isolation of a human-derived Coronavirus in Vero E6 cells was unexpected.

As mentioned before, the isolation of a human-derived Coronavirus in Vero cells is a new finding that can go a long way in understanding viral mutations and virus interactions. It could be possible that the virus plays a secondary role in aggravating the conditions caused by the SARS virus

Weak Points

Even though the paper presents exciting material, it also has its fair share of weak points

1. Only a possible link between Coronavirus and the SARS virus have been indicated in the paper.

The link between SARS and the isolated virus is not proved beyond doubt in the paper. It may take many more years of research to prove or disprove the link, if any.
Similarly, the authors were also not able to prove the incidence of SARS-related Coronavirus infection in all patients who had SARS.

2. The exact reasons for the virus not being associated with all SARS patients are not made clear by the authors.

The authors have not been able to explain why the virus is not seen in all SARS patients. This raises doubts about the role of the virus in SARS because Coronaviruses are associated with the thoracic parts of the normal human body. In addition, the authors themselves agree that the cause of SARS could be due to many other pathogens. Since Coronaviruses have been associated with respiratory diseases like cold, it is quite possible that they might have been found at the site of SARS infection as a matter of chance, and so the observation does not point to the fact that they could have caused SARS in the first place.

3. The fact that the antigens of the virus could not be detected in the body parts of the patients, puts to doubt the assumption that these viruses indeed cause SARS [Ksiazek et al., pp11]