Relationship between plaque size and the immunising ability of the foot-and-mouth disease virus SAT1 Nig 10/75

1981 ◽  
Vol 70 (1) ◽  
pp. 63-67 ◽  
Author(s):  
K. J. Preston ◽  
Hilary Owens ◽  
G. N. Mowat
2006 ◽  
Vol 81 (4) ◽  
pp. 1879-1887 ◽  
Author(s):  
Roberto Mateo ◽  
Mauricio G. Mateu

ABSTRACT The evolution of foot-and-mouth disease virus (FMDV) (biological clone C-S8c1) in persistently infected cells led to the emergence of a variant (R100) that displayed increased virulence, reduced stability, and other modified phenotypic traits. Some mutations fixed in the R100 genome involved a cluster of highly conserved residues around the capsid pores that participate in interactions with each other and/or between capsid protomers. We have investigated phenotypic and genotypic changes that occurred when these replacements were introduced into the C-S8c1 capsid. The C3007V and M3014L mutations exerted no effect on plaque size or viral yield during lytic infections, or on virion stability, but led to a reduction in biological fitness; the D3009A mutation caused drastic reductions in plaque size and viability. Remarkably, competition of the C3007V mutant with the nonmutated virus invariably resulted in the fixation of the D3009A mutation in the C3007V capsid. In turn, the presence of the D3009A mutation invariably led to the fixation of the M3014L mutation. In both cases, two individually disadvantageous mutations led, together, to an increase in fitness, as the double mutants outcompeted the nonmutated genotype. The higher fitness of C3007V/D3009A was related to a faster multiplication rate. These observations provide evidence for a chain of linked, compensatory mutational events in a defined region of the FMDV capsid. Furthermore, they indicate that the clustering of unique amino acid replacements in viruses from persistent infections may also occur in cytolytic infections in response to changes caused by previous mutations without an involvement of the new mutations in the adaptation to a different environment.


Author(s):  
S. S. Breese ◽  
H. L. Bachrach

Models for the structure of foot-and-mouth disease virus (FMDV) have been proposed from chemical and physical measurements (Brown, et al., 1970; Talbot and Brown, 1972; Strohmaier and Adam, 1976) and from rotational image-enhancement electron microscopy (Breese, et al., 1965). In this report we examine the surface structure of FMDV particles by high resolution electron microscopy and compare it with that of particles in which the outermost capsid protein VP3 (ca. 30, 000 daltons) has been split into smaller segments, two of which VP3a and VP3b have molecular weights of about 15, 000 daltons (Bachrach, et al., 1975).Highly purified and concentrated type A12, strain 119 FMDV (5 mg/ml) was prepared as previously described (Bachrach, et al., 1964) and stored at 4°C in 0. 2 M KC1-0. 5 M potassium phosphate buffer at pH 7. 5. For electron microscopy, 1. 0 ml samples of purified virus and trypsin-treated virus were dialyzed at 4°C against 0. 2 M NH4OAC at pH 7. 3, deposited onto carbonized formvar-coated copper screens and stained with phosphotungstic acid, pH 7. 3.


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