One Virus Particle Enough to Cause Infection

A study has shown that an exposure to even a single virus particle would be enough to theoretically cause an infection or disease. There was no previous proof to support this until the researchers from Wageningen University and Simon Fraser University in Canada conducted an experimental study with insect larvae.

The team of researchers conducted the study by trying to expose two marked variants of a certain virus to a population of hosts, which were caterpillars. A virus population is generally composed of a collection of several variants of virus particles or virions. The researchers wanted to determine whether selected virus particles can be enough to cause infection independently of each other. This led to the team experimenting with having two tagged variants of a virus and exposing it to a host.

The experiment showed that the hosts which were exposed to a low dosage of virus particles led to a small number of host infections, around 20 percent overall. Around 86 percent of those infected became infected by a single virus genotype. Exposure to a high dose of virus particles led to almost 99 percent of the hosts to become infected with most of the hosts infected with both types of virus particles. Around 14 percent ended up being infected by only one of the two virus variants.

Before this study, it was unclear to scientists whether a virus should be considered as a single entity that works independently to infect a host or whether to consider it as a group of virus variants cooperating to cause an infection. The results of the experiment showed that it is possible for a host to be infected by a single virus variant independently that normally works together with other variants.

The number of virus particles will determine the degree of diversity present in an infected host. How the different virus particles interact with each other may affect the progression of the disease and the evolution of the virus itself. But it is also possible that a single virus particle can be enough to cause infection.

Source: Wageningen University and Research Centre. "One Virus Particle Is Enough To Cause Infectious Disease." ScienceDaily 14 March 2009. 6 May 2009