Introduction
One of the families of ssRNA viruses which cause upper respiratory tract diseases in humans and birds is the Coronaviridae family. Although the coronaviruses are known since the early 60s (229 and OC43 viruses), they started attracting attention only since 2003, when a virus causing a severe acute respiratory syndrome (SARS) was discovered in an outbreak that took place in southern China and then spread into several countries.1 Ten years after this event, which was responsible of 774 deaths in over 30 countries (of 8000 confirmed cases), a new “SARS-like” infection emerged from the Middle East and was named as Middle East respiratory syndrome coronavirus (MERS-CoV) by the Coronavirus Study Group of the International Committee for Taxonomy of Viruses. Samples taken from two patients with severe cases of community-acquired pneumonia (Bisha, KSA and Doha, Qatar) contributed to the first isolation of the new virus and its sequencing.2 The novel virus was isolated several other times from locals and tourists of the Arabian Peninsula presenting symptoms which resembled those of the first documented victims of the disease. In retrospect, a group of respiratory infections which took place earlier in Jordan (April 2012) was related to this viral agent.3
The genome analysis of MERS-CoV classified the emerging virus as a member of the lineage C of the genus Betacoronavirus. Interestingly, its closest known relatives are present in bats (HkU-4 and HkU-5). In contrast, it is more distantly related to the SARS-CoV not only genetically, but also in means of the virus receptor usage.3
Virion structure and composition
All coronaviruses have four structural proteins in common (Figure 1): a large surface glycoprotein (S; 1150–1450 ami...
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...Lancet Infect. Dis. 9, 291–300 (2009).
10. WHO | MERS-CoV summary updates. WHO at
11. CDC - Coronavirus - Middle East Respiratory Syndrome - MERS-CoV. at
12. Zhou, N., Zhang, Y., Zhang, J.-C., Feng, L. & Bao, J.-K. The receptor binding domain of MERS-CoV: The dawn of vaccine and treatment development. J. Formos. Med. Assoc. 113, 143–147 (2014).
13. Watson, J. T., Hall, A. J., Erdman, D. D., Swerdlow, D. L. & Gerber, S. I. Unraveling the Mysteries of Middle East Respiratory Syndrome Coronavirus. Emerg. Infect. Dis. 20, 1054–1056 (2014).
14. Cavanagh, D. in Princ. Pract. Clin. Virol. (Microbiology, A. J. Z. of M., Virology, J. E. B. E. of C., Pattison, J. R., Virology, P. D. G. of & Director, B. D. S. E.) 379–397 (John Wiley & Sons, Ltd, 2004).
Rabies virus belongs to Lyssavirus genus, Rhadboviridae family. It is a negative-sense, non-segmented, single-strand RNA and 180 nm long* 75 nm wide bullet-shape virus. All rhabdoviruses have two main structural components: a helical ribonucleoprotein (RNP) complex and a surrounding viral envelope. The rabies virus genome encodes five functional proteins: L (transcriptase), N (nucleoprotein), and NS (transcriptase-associated) protein with viral RNA are composed of the RNP complex. This complex adds up in the cytoplasm of neurons that are infected by rabies virus and makes up Negri body that is an indicator of rabies for histopathologists. Another two proteins are M (matrix) and G (glycoprotein) proteins that are associated with the lipid envelope. The G protein shapes the protrusions that are spikes-shape surface antigen on the virion envelope and induce virus-neutralizing antibody.
The virus is primarily spherical shaped and roughly 200nm in size, surrounded by a host-cell derived membrane. Its genome is minus-sense single-stranded RNA 16-18 kb in length. It contains matrix protein inside the envelope, hemagglutinin and neuraminidase, fusion protein, nucleocapsid protein, and L and P proteins to form the RNA polymerase. The host-cell receptors on the outside are hemagglutinin and neuraminidase. The virus is allowed to enter the cell when the hemagglutinin/ neuraminidase glycoproteins fuse with the sialic acid on the surface of the host cell, and the capsid enters the cytoplasm. The infected cells express the fusion protein from the virus, and this links the host cells together to create syncitia.
ICAM-1 is regularly used by the immune system to bind endothelial cells to leukocytes. However, as the picture above shows, Rhinovirus is able to take advantage of this property and recognizes it with its own receptors.
Poliovirus binds to a specific cell surface protein, polio virus receptor (PVR). This protein is an immunoglobin which contains three loops, Ig domains. Polio binds...
“This knowledge will help us design drugs that mimic the viral effects on these proteins to either activate a host’s immune response or shut it down,” said Dr. Michael Gale, associate ...
The size of the swine flu virus ranges anywhere from ten to three hundred nanometers in diameter. In comparison to real world measurements, one nanometer is one one-millionth of a millimeter. The shape overall is a sphere which means it targets members of the animal kingdom like mammals. The swine flu virus is not categorized in a kingdom, phylum, or class because it is not considered to be living. However, it is part of the order of mononegavirales which includes all viruses that can infect any of the six kingdoms. The family is orthomyxoviridae which is all spheri...
Hvistendahl, M, Cohen, J et. al. 2013. ‘New Flu Virus in China Worries and Confuses’ Science 340: 129-130
Hemagglutinin (HA) is an antigenic receptor-binding glycoprotein found on the surface of the influenza viruses. Its molecular structure has been classified as a homotrimer with each monomer being the precursors to HA1, head region, and HA2, stem region. The stem region, which contains conserved proteins common among other influenza pandemic strains, are currently being explored for vaccination opportunities, along with the variable head region where antibodies target and bind to elicit immune
Severe acute respiratory syndrome (SARS) is an upper respiratory infection caused by a coronavirus. The etiological agent responsible for SARS is called SARS-associated coronavirus (SARS-CoV). SARS-CoV is a relatively novel mutated form of coronavirus, resulting in a virus capable of becoming infectious in a human host. Typically, coronaviruses express themselves much like a common cold. However, SARS-CoV can cause complications uncommon in other coronavirus strains. A host infected with SARS-CoV may develop additional infections, like pneumonia or respiratory failure6,7. According to the World Health Organization (WHO),37 SARS-CoV presents itself as an atypical cold but with similar symptoms, resulting in a virulent pathogen
The “Aussie flu”, an Australian influenza virus, has made headlines on media worldwide. It is suggested that the Australian strain has spread to other countries, which has led to criticism of Australia’s Public Health policies. Although, is it possible to identify a strain’s source? If so, how did this “Aussie flu” become so harmful, could it have been prevented? The media is comparing this year’s flu outbreak to the 1968 Hong Kong flu, is it really the next flu pandemic? Influenza viruses are ever evolving and resisting to antibiotic treatment. This is a Global Health issue, particularly making an impact in Australia.
This extremely pathogenic zoonotic virus is now understood to travel from bat species, to equine intermediate hosts, to humans.[8, 10] The Hendra virus is listed as a Bio-Safety Level (BSL)-4, and can only be studied at a few adequately equipped laboratories worldwide due to its virulence.[1, 2] Case fatality rates
Murray, M.2006. The epidemiology of SARS. In SARS in China: Prelude to pandemic?, ed. A. Kleinman and J. Watson, 17-30. Stanford, Calif.: Stanford University Press.
In 1918-19 approximately 50 million deaths were a detriment of the Spanish H1N1 virus pandemic; a respiratory virus. According to the World Health Organization, the second Influenza A H1N1 pandemic in 2009 spread to more than 200 countries causing more than 18 000 deaths. Before the World Health Organization had announced the official end of the pandemic in August 2010, in July 2009 the World Health Organization sent out a phase 6 warning that H1N1 could soon be a global pandemic. It is important to recognize that the 2 different outbreaks had different A/H1N1strains effecting the world population; this suggests A/H1N1has a high ability for mutation, severely complicating the human body’s natural immune mechanism of antigenic drift. (Qi-Shi Du et al., 2010)
World Health Organization “Frequently Asked Questions on Severe Acute Respiratory Syndrome (SARS),” Communicable Disease Surveillance & Response (CSR), March 24. (2003). World Health Organization . Retrieved March 29, 2004.
The DENV envelope protein E, which is found on the virus surface, has a role as a mediating factor in the initial attachment of the virus to the host cell. Further, several cellular proteins and carbohydrate molecules that act as attachment factors interacting with the viral envelope protein E have been identified. These factors allow the virus population to concentrate on the cell surface thus increasing their chance of access to their target cellular receptor(s). Some of these known molecules that interact with the vi...