Viral Diseases Background

Documents Publications Viral Diseases Test Info

• Functions
• Proficiency Panels
• Characterization of Isolates
• Recent Discoveries

The Viral Diseases Division is the National reference laboratory for a number of viral diseases, including hepatitis viruses A-E, respiratory viruses and influenza, viral exanthemata (rash causing viruses such as chickenpox and measles) viral STDs (including herpes simplex viruses and human papilloma viruses) and enteroviruses (including polio virus, coxsackie viruses, and echo viruses, that can cause diseases such as flaccid paralysis, cardiomyopathy, hand-foot-and-mouth disease, and aseptic meningitis).  The Division also diagnoses disease due viral gastroenteritis agents, such as norovirus.  Among these are some of the most widespread, numerous and life-threatening viral infections which affect the health of Canadians.  Diagnosis and surveillance of these diseases is essential for prevention and treatment strategies in patients (e.g. vaccination strategies), and in order to reduce illness, hospitalizations and deaths from these diseases. 

The Viral Diseases Division carries out research into the molecular biology and epidemiology of these viral agents.  It undertakes applied research to develop improved diagnostic tests and also basic research of a fundamental nature, to understand the pathogenesis of these viruses.  

The Division consists of the following sections:

• Bloodborne Pathogens & Hepatitis
• Influenza and Respiratory Viruses
• Viral Exanthemata
• Viral Sexually Transmitted Diseases
• Enteroviruses and enteric viruses

Functions

One of the main functions of the laboratory is to isolate and characterize new or unknown virus infections.  This includes providing a unique national and internationally recognized laboratory reference service to Canadian and other national laboratories (which frequently involve collaboration with our counterparts in the United States and Europe), for the diagnosis or characterization of unusual or difficult patient specimens or isolates of infectious agents. 

Other functions are to carry out surveillance, particularly for agents which may be present in blood and therefore transfused into patients or which may expand rapidly in high-risk populations, such as intravenous drug abusers.  This work has an impact on blood safety, and research on emerging pathogens which may be a new or unrecognized threat to humans. An emerging disease is either a new disease, such as SARS, or an old disease in a new situation such as H5N1 avian influenza, or a disease that existed previously but was not recognized, such as human coronavirus NL63.

Proficiency Panels

The Division also provides proficiency panels to many other laboratories in Canada for quality monitoring of the specificity and sensitivity of their testing systems for HBV and HCV markers, influenza and measles/rubella.  Thirty to thirty-five laboratories participate in the panels that are conducted annually.

The primary clients for the reference service and the proficiency panels are the Provincial Public Health Laboratories (PPHLs) and large hospital laboratories, but these include other international laboratories especially in the case of new or unusual infections. This includes an element of troubleshooting for PPHLs to characterize indeterminate specimens.  These are specimens from which they have obtained conflicting results using two or more different tests.   The program is able to advise on test procedures and on the selection of testing algorithms and does work to evaluate commercially available test kits.

Characterization of Isolates

The functions of the viral reference laboratory are the maintenance of collections of virus isolates, and data on the characterization of these samples using different test methods, and providing a testing service to other laboratories to confirm or characterize unknown specimens.  These tests include commercial kits as well as in-house kits, and are immunologically based, nucleic acid based (hybridization or PCR) or based on isolation and propagation (amplification) of viruses in culture systems.

Recent Discoveries

A large proportion of the agents that can cause human illness still cannot be attributed to known pathogens.  Examples of this are the recent discoveries of human metapneumovirus and coronavirus NL63, that are new to science. 

The Viral Diseases Division has been testing specimens taken from patients with flu-like symptoms in previous years, that had tested negative for most viruses that cause colds and flu such as orthomyxoviruses (influenza-like virus), paramyxoviruses, adenoviruses or human coronaviruses that could be isolated by culture or detected with serological or nucleic acid tests. 

Recent analysis has shown that one of two newly discovered types of virus was present in some of these specimens, which could not be recognised by conventional tests for respiratory viruses.   We now know, through retrospective studies, that variants of human coronavirus NL63, and human metapneumovirus, are present in many specimens from previous years and appear to have been circulating commonly in Canada.  New laboratory tests developed by the Division for these viruses have now been introduced for routine diagnosis of respiratory disease. 

The Viral Diseases Division frequently shares any new virus isolates, as well as antisera and other reagents with other national reference laboratories abroad. In the case of any new or unidentified viruses, confirmatory results from a second, independent laboratory is generally obtained, once analyses characterization undertaken by the Viral Diseases Division  are complete.