Defra - Department for Environment, Food and Rural Affairs.

Science Search

Science and Research Projects

Return to Science Search homepage   Return to Project List

An in vitro study to establish wheter defined non-feline cell lines are competent to produce RD114 virus particles capable of replication. - VM0501

Many of the most effective veterinary vaccines are based upon "attenuated" viruses, viruses that have been disabled such that they do not cause disease in healthy animals. When an animal is vaccinated with an attenuated virus vaccine, the animal mounts a strong immune response against the vaccine virus and yet suffers only very mild or no signs of disease. The animal is then immune to infection with a disease-causing strain of the virus (a "virulent" virus). In order to prepare stocks of attenuated viruses for use in veterinary vaccines, vaccine viruses are grown with "in vitro" laboratory cell culture systems using mammalian cell lines. For example, dog cell lines may be used to grow attenuated canine adenovirus type 2 (CAV-2), a virus that contributes to the condition known as "kennel cough" .
Just as dogs and cats may be infected with a range of different viruses, the mammalian cell lines used to grow vaccine viruses are also susceptible to infection with many different viruses. Vaccine producers must operate the highest standards of hygiene to prevent the accidental infection of the vaccine-producer cell lines with other viruses. Thus, it is important that stocks of attenuated virus vaccines prepared in mammalian cell lines are monitored closely for contamination with other viruses. Recent studies have demonstrated that a virus of cats (known as RD114) can infect some of the mammalian cell lines used in vaccine production and may therefore find its way into attenuated virus vaccines. RD114 belongs to a family of viruses known as retroviruses and is an example of an “endogenous” retrovirus (ERV); a virus that has become attenuated in its natural host and which is no longer capable of causing disease. Copies of RD114 are present in the DNA of every domestic cat and while small amounts of RD114 virus are made in cat cells, they are neither released by the cat nor transmitted between animals. While RD114 is thought to be harmless in cats, little is known about the likely effects of an accidental transmission of the virus to other species such as dogs. It is important therefore, to ensure that the cell culture systems used to prepare veterinary vaccines are designed such that the risk of contamination with RD114 is eliminated. In this proposal, we investigate the growth of RD114 in a range of mammalian cell lines that are used to grow vaccine viruses. The likelihood of transmission of RD114 and the barriers to RD114 growth will be estimated. Informed by these studies, we will be able to ensure that future veterinary vaccines are free from unwanted contaminants.
Phase 1 – 12 months (2011-2012)

Objective 1 - To ascertain whether non-feline cell lines support viral growth following infection with RD114.

Objective 2 - To examine the effect of co-infection with vaccine viruses on susceptibility to RD114 infection and replication.

Phase 2 – 24 months (2012-2014)

Objective 3 - To ascertain whether 12 additional non-feline cell lines support viral growth following infection with RD114.

Objective 4 - To examine the effect of co-infection with vaccine viruses on susceptibility of 12 additional lines to RD114 infection and replication.
Project Documents
• EVID4 - Final project report : VM0501 Final Report   (2208k)
Time-Scale and Cost
From: 2011

To: 2015

Cost: £207,288
Contractor / Funded Organisations
University of Glasgow
Veterinary Medicines