An antibody escape-mutant of coxsackievirus B3 / CVB3 (RK strain) was isolated using
a neutralising monoclonal antibody against CVB3. This escape-mutant EM1 was then
compared with the wt+ strain CVB3 (RK) both in vitro and for its pathogenesis in mice.
In vitro EM1 was found to be temperature sensitive at 40°C and less stable on
prolonged incubation at 37°C than CVB3 (RK). Also EM1 was slightly growth-restricted
in Vero cells, giving yields 2 to 5 fold lower than the parental strain and also has a small
plaque phenotype. A similar reduction in viral replication was found in the macrophage
cell-line, J774A.1. However growth of EM1 in the Wehi 231 B-cell-line was reduced 10-
20 fold while both EM1 and wt+ were totally restricted in the T-cell-line, EL-4.
In vivo. EM1 was found to be less myocarditic while producing equivalent amount of
pathological damage in pancreas and liver. Correlating with this equivalent amounts of
virus were detected both by plaque assay of tissue homogenates, and in situ
hybridization in all tissues apart from spleen and heart. In particular in heart tissue, the
ability of the EM1 to replicate and cause damage was much less than the wt+(RK)
strain, i.e., EM1 was less cardiovirulent than CVB3 (RK).
Sequence analysis of the NTR region and P1 structural gene regions of CVB3 (RK) and
EM1 strains following RT/PCR of genomic RNA identified several mutations in EM1
including a single nucleotide change in the E loop of the NTR region and several
mutations in P1. The most significant changes appear to be in VP1 where 4 point
mutations and a deletion/insertion were identified. One of these is silent but the others
are associated with amino acid changes including T to H and F to V substitutions in the
BD region of VP1 structure. These mutations most likely explain the lack of reactivity
with neutralising MAb and also the reduced heat stability of EM1. / Medicine, Faculty of / Pathology and Laboratory Medicine, Department of / Graduate
| Identifer | oai:union.ndltd.org:UBC/oai:circle.library.ubc.ca:2429/6010 |
| Date | 11 1900 |
| Creators | Sadeghi, Assai Mir Mohammad |
| Source Sets | University of British Columbia |
| Language | English |
| Detected Language | English |
| Type | Text, Thesis/Dissertation |
| Format | 12458853 bytes, application/pdf |
| Rights | For non-commercial purposes only, such as research, private study and education. Additional conditions apply, see Terms of Use https://open.library.ubc.ca/terms_of_use. |
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