|Duffus, Amanda Linda Jean
|The ranaviruses (Family: Iridoviridae) are a group of emerging pathogens in
amphibians. Ranavirus(es) were introduced to the UK in the late 1980s and have
been associated with mass mortality events in common frogs (Rana temporaria) in
south east England. While the signs associated with the disease are well known in
common frogs, little is known about the ecology of the disease in any amphibians in
the UK. This thesis begins the process of the eludication of the ecology of the
ranavirus in common frogs. To test the two different hypotheses for the
transmission/maintenance of ranavirus(es) in North American amphibians,
investigations into the life history stages of common frogs (Rana temporaria)
affected by the ranavirus were undertaken. Eggs and tadpoles were screened using
standard molecular methodologies for the presence of the virus. No infections were
found in eggs (n = 720), one infection was found in a tadpole (n = 288), but adults
were commonly infected with the virus. A mathematical model was developed to
investigate if the ranavirus could be maintained in populations of common frogs
when only adult-to-adult horizontal transmission of the ranavirus occurred. Under
certain circumstances, the virus can persist for long periods of time when this occurs.
This is the first attempt to mathematically quantify the dynamics of a ranavirus.
The potential of alternate or reservoir hosts of the ranavirus(es) in the UK
were also examined. This permitted for the identification of new amphibian host and
for the isolation and characterization of ranaviruses from different hosts.
Phylogenetic analyses revealed that all of the viral isolates were genetically similar at
both loci examined.
Experimental work examining the association between ranavirus isolates
from different hosts in common frog and common toad (Bufo bufo) tadpoles was also
performed. At low doses, isolates from common frogs caused higher mortality in
common frog tadpoles than isolates from common toads. However, in common toad
tadpoles, no such relationship was observed.
|Queen Mary University of London Research Studentship.
Overseas Research Studentship.
Natural Science and Engineering Council (NSERC)of Canada Doctoral Scholarship (PDS-D3.
Amphibian Convocation Trust Grant University of London.
British Wildlife Health Research Grant.
British Herpetological Grant Society.
|Ranavirus ecology in common frogs (Rana Temporaria) from United Kingdom: transmission dynamics, alternate hosts and host-strain interactions.
|The copyright of this thesis rests with the author and no quotation from it or information derived from it may be published without the prior written consent of the author