The ethics of research involving animals - Nuffield Council on ...
The ethics of research involving animals - Nuffield Council on ...
The ethics of research involving animals - Nuffield Council on ...
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T h e e t h i c s o f r e s e a r c h i n v o l v i n g a n i m a l s<br />
Researchers used large volumes <str<strong>on</strong>g>of</str<strong>on</strong>g> blood from an infected chimpanzee with a high level <str<strong>on</strong>g>of</str<strong>on</strong>g><br />
infecti<strong>on</strong> to isolate the virus. Proteins in the chimpanzee blood were then screened against<br />
serum from a NANB hepatitis patient, which was expected to c<strong>on</strong>tain anti-NANB hepatitis<br />
antibodies. Eventually a NANB hepatitis viral protein in the chimpanzee blood was found to<br />
react with antibodies from the human patient, possibly due to the high levels <str<strong>on</strong>g>of</str<strong>on</strong>g> viral<br />
particles in the chimpanzee blood. With the genome available, it was possible to develop<br />
reliable diagnostic tests for what was subsequently termed hepatitis C. Treatment strategies<br />
have also been developed in <str<strong>on</strong>g>animals</str<strong>on</strong>g> although a vaccine does not yet exist.<br />
6.26 <str<strong>on</strong>g>The</str<strong>on</strong>g> <str<strong>on</strong>g>animals</str<strong>on</strong>g> in the study described above could be expected to suffer symptoms similar<br />
to those experienced by humans, especially at high infecti<strong>on</strong> doses. According to the US<br />
Nati<strong>on</strong>al Center for Infectious Diseases, 80 percent <str<strong>on</strong>g>of</str<strong>on</strong>g> people with hepatitis C have little<br />
or no signs or symptoms, whereas others may experience jaundice, fatigue, dark urine,<br />
abdominal pain, loss <str<strong>on</strong>g>of</str<strong>on</strong>g> appetite, nausea and eventually chr<strong>on</strong>ic liver disease. 25<br />
Additi<strong>on</strong>al implicati<strong>on</strong>s for welfare relate to the l<strong>on</strong>g-term husbandry <str<strong>on</strong>g>of</str<strong>on</strong>g> the infected<br />
<str<strong>on</strong>g>animals</str<strong>on</strong>g> as they may be infectious to other <str<strong>on</strong>g>animals</str<strong>on</strong>g> and to humans, and must therefore<br />
be kept in single housing.<br />
6.27 <str<strong>on</strong>g>The</str<strong>on</strong>g> major cause <str<strong>on</strong>g>of</str<strong>on</strong>g> hepatitis C infecti<strong>on</strong> was formerly blood transfusi<strong>on</strong>. 26 It is now routine<br />
to screen d<strong>on</strong>ated blood for hepatitis C, which has vastly reduced transfusi<strong>on</strong>-mediated<br />
infecti<strong>on</strong> in industrialised countries. <str<strong>on</strong>g>The</str<strong>on</strong>g> discovery and characterisati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> the virus, its role<br />
as the etiological agent and the mechanisms whereby it produced disease in chimpanzees<br />
led to an understanding <str<strong>on</strong>g>of</str<strong>on</strong>g> the primary role <str<strong>on</strong>g>of</str<strong>on</strong>g> the virus in post-transfusi<strong>on</strong> hepatitis and its<br />
tendency to induce persistent infecti<strong>on</strong> and chr<strong>on</strong>ic liver disease. Approximately 170 milli<strong>on</strong><br />
people worldwide are chr<strong>on</strong>ically infected with hepatitis C, 27 many <str<strong>on</strong>g>of</str<strong>on</strong>g> whom will develop<br />
cirrhosis and liver cancer.<br />
6.28 Because <str<strong>on</strong>g>of</str<strong>on</strong>g> the l<strong>on</strong>g asymptomatic period (up to 20 years), most infected people are<br />
unaware that they carry the virus and c<strong>on</strong>tinue to be a source <str<strong>on</strong>g>of</str<strong>on</strong>g> new infecti<strong>on</strong>s.<br />
Diagnostic assays to detect the virus are therefore essential to identify these patients.<br />
Current work <strong>on</strong> chimpanzees is not permitted in the UK, as the Home Office does not<br />
grant licences for <str<strong>on</strong>g>research</str<strong>on</strong>g> <str<strong>on</strong>g>involving</str<strong>on</strong>g> the great apes (see paragraph 13.6). Without the<br />
<str<strong>on</strong>g>research</str<strong>on</strong>g> described above, very little would be known about hepatitis C, and diagnostic<br />
tests would not be available. Many scientists believe that the lack <str<strong>on</strong>g>of</str<strong>on</strong>g> a reliable animal<br />
model other than the chimpanzee is the single greatest barrier blocking the development<br />
<str<strong>on</strong>g>of</str<strong>on</strong>g> a safe and effective vaccine.<br />
Study <str<strong>on</strong>g>of</str<strong>on</strong>g> polio and the development <str<strong>on</strong>g>of</str<strong>on</strong>g> polio vaccine<br />
6.29 Animal disease models have been used in the study <str<strong>on</strong>g>of</str<strong>on</strong>g> poliomyelitis (polio), enabling an<br />
understanding <str<strong>on</strong>g>of</str<strong>on</strong>g> the disease process at the cellular level and facilitating the subsequent<br />
development <str<strong>on</strong>g>of</str<strong>on</strong>g> an effective vaccine. <str<strong>on</strong>g>The</str<strong>on</strong>g> polio virus enters the body through the mouth,<br />
from where it can travel to the digestive system and enter the bloodstream. <str<strong>on</strong>g>The</str<strong>on</strong>g> virus<br />
invades the CNS and destroys motor nerve cells, leading to paralysis and sometimes death.<br />
Before vaccines were introduced in developed countries in the late 1950s and early 1960s,<br />
polio was a comm<strong>on</strong> disease, estimated to be resp<strong>on</strong>sible for crippling more than half a<br />
25 Nati<strong>on</strong>al Center for Infectious Diseases (2005) Viral Hepatitis C, available at:<br />
http://www.cdc.gov/ncidod/diseases/hepatitis/c/fact.htm. Accessed <strong>on</strong>: 26 Apr 2005.<br />
26 Alter HJ, Purcell RH, Shih JW et al. (1989) Detecti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> antibody to hepatitis C virus in prospectively followed transfusi<strong>on</strong><br />
recipients with acute and chr<strong>on</strong>ic n<strong>on</strong>-A, n<strong>on</strong>-B hepatitis N Engl J Med 321: 1494–500.<br />
27 World Health Organizati<strong>on</strong> (2000) Fact sheet No. 164 Hepatitis C, available at:<br />
http://www.who.int/mediacentre/factsheets/fs164/en/. Accessed <strong>on</strong>: 26 Apr 2005.<br />
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