Search results for " India"

r- and K-selection in experimental populations of vesicular stomatitis virus.

2002

Here we explore the adaptation of vesicular stomatitis RNA virus to different population densities and the existence of a trade-off between r- and K-selection. Increasing population density represents a challenging special situation for viruses, since different selective pressures arise depending upon the number of available host cells per virus. Adaptation to low density represents a prototypical case of r-selection, where the optimal evolutionary solution should be a high replication rate. Adaptation to high density represents a case of K-selection. In this case, genotypes optimally exploiting the resources, instead of faster replicating ones, should be selected. Five independent populati…

Mode of selection and experimental evolution of antiviral drugs resistance in vesicular stomatitis virus

2004

Abstract The possession of an antiviral resistance mutation benefits a virus when the corresponding antiviral is present. But does the resistant virus pay a fitness cost when the antiviral is absent? Would an evolutionary history of association between a genotype and a resistance mutation overcome this cost by changes compensating the harmful side-effect of resistance mutations? Are combined therapies more effective against the rise of resistant viruses or against evolutionary compensations? To explore all these questions, we took an experimental evolution approach. After selecting vesicular stomatitis virus (VSV) populations able to replicate under increasing concentrations of ribavirin an…

Evolutionary history conditions the timing of transmission in vesicular stomatitis virus.

2001

It has been postulated that early transmitted viruses would evolve to be more virulent than late transmitted ones. The reason for this prediction is that early transmission selects for rapid viral replication and, consequently, rapid host death, whereas late transmission would select for slow-replicating viruses that permit longer survival to the host. To test this prediction, experimental lineages of vesicular stomatitis virus (VSV) had been adapted to three different transmission dynamics during more than 100 generations. Transmission dynamic differed in the stage of infection at which transmission took place: early, intermediate or late. Regardless the timing of transmission imposed duri…

The effect of co- and superinfection on the adaptive dynamics of vesicular stomatitis virus

2006

In many infectious diseases, hosts are often simultaneously infected with several genotypes of the same pathogen. Much theoretical work has been done on modelling multiple infection dynamics, but empirical evidences are relatively scarce. Previous studies have demonstrated that coinfection allows faster adaptation than single infection in RNA viruses. Here, we use experimental populations of the vesicular stomatitis Indiana virus derived from an infectious cDNA, to show that superinfection dynamics promotes faster adaptation than single infection. In addition, we have analysed two different periodicities of multiple infection, daily and separated 5 days in time. Daily multiple infections al…

Social evolution of innate immunity evasion in a virus

2019

Antiviral immunity has been studied extensively from the perspective of virus−cell interactions, yet the role of virus−virus interactions remains poorly addressed. Here, we demonstrate that viral escape from interferon (IFN)-based innate immunity is a social process in which IFN-stimulating viruses determine the fitness of neighbouring viruses. We propose a general and simple social evolution framework to analyse how natural selection acts on IFN shutdown and validate it in cell cultures and mice infected with vesicular stomatitis virus. Furthermore, we find that IFN shutdown is costly because it reduces short-term viral progeny production, thus fulfilling the definition of an altruistic tr…

Transmission bottlenecks and the evolution of fitness in rapidly evolving RNA viruses

2003

We explored the evolutionary importance of two factors in the adaptation of RNA viruses to their cellular hosts, size of viral inoculum used to initiate a new infection, and mode of transmission (horizontal versus vertical). Transmission bottlenecks should occur in natural populations of viruses and their profound effects on viral adaptation have been previously documented. However, the role of transmission mode has not received the same attention. Here we used a factorial experimental design to test the combined effects of inoculum (bottleneck) size and mode of transmission in evolution of vesicular stomatitis virus (VSV) in tissue culture, and compared our results to the predictions of a …

Diminishing Returns of Population Size in the Rate of RNA Virus Adaptation

2000

ABSTRACT Whenever an asexual viral population evolves by adapting to new environmental conditions, beneficial mutations, the ultimate cause of adaptation, are randomly produced and then fixed in the population. The larger the population size and the higher the mutation rate, the more beneficial mutations can be produced per unit time. With the usually high mutation rate of RNA viruses and in a large enough population, several beneficial mutations could arise at the same time but in different genetic backgrounds, and if the virus is asexual, they will never be brought together through recombination. Thus, the best of these genotypes must outcompete each other on their way to fixation. This c…

Il teatro orientale

2004

Panoramic radiographic study of mental foramen in selected dravidians of south Indian population: A hospital based study

2015

Background: This study aimed at documenting information on appearance, size, horizontal and vertical locations of Mental Foramen (MF) in Panoramic Radiograph. We also analyzed the age and gender differences with radiographic appearance and location of MF. We evaluated these findings in our population and co-relate with results of previous studies. Material and Methods: 1662 panoramic radiographs were evaluated, of which 245 fulfilled the inclusion criteria. Each radiograph was traced to record the horizontal and vertical locations. The size of MF was recorded using digital caliper and its appearance was determined by visual examination. Chi-square and t-test were employed. Results: The most…

Enhanced baculovirus-mediated transduction of human cancer cells by tumor-homing peptides.

2006

ABSTRACT Tumor cells and vasculature offer specific targets for the selective delivery of therapeutic genes. To achieve tumor-specific gene transfer, baculovirus tropism was manipulated by viral envelope modification using baculovirus display technology. LyP-1, F3, and CGKRK tumor-homing peptides, originally identified by in vivo screening of phage display libraries, were fused to the transmembrane anchor of vesicular stomatitis virus G protein and displayed on the baculoviral surface. The fusion proteins were successfully incorporated into budded virions, which showed two- to fivefold-improved binding to human breast carcinoma (MDA-MB-435) and hepatocarcinoma (HepG2) cells. The LyP-1 pepti…