Virus hijacking insect sperm causes brutal sterility, find scientists
Penn State researchers unveil the tale of Wolbachia and its viral accomplice manipulating insect reproduction.
There is now a very unlikely way to combat insects. Imagine this: a tiny bacteria named Wolbachia and its accomplice, a virus called prophage WO, are causing sterility in male insects by hijacking their sperm, preventing them from fertilizing eggs of females that do not have the same bacteria and virus.
A new study led by microbiome researchers at Penn State shows how this bacterial and virus combination manipulates sperm and drastically reduces insect population by the numbers. It could lead to refined techniques to control populations of agricultural pests and insects that carry diseases like Zika and dengue to humans.
First, let’s talk about the bacteria itself. Wolbachia is the most widespread bacteria in animals. It lives symbiotically within the reproductive tissues of about 50 percent of insect species, including some mosquitos and flies,” said Seth Bordenstein, professor of biology and entomology and one of the research team’s leaders.
And it is not just a bacteria in itself. Many bacteria organisms usually have a prophage attached to them. They are called bacteriophages. In this case, Wolbachia has genes from a virus called prophage WO integrated into its genome. The genes include cifA and cifB. They are the masterminds behind the discovery of this study
cifA and cifB allow the bacteria to manipulate sperm and quickly spread through an insect population for their good. So, when both male and female versions of the species mate and have the Wolbachia bacteria, it is passed on to their offspring.
Wolbachia virus is the key to new offspring
However, when a male with Wolbachia mates with a female with no Wolbachia, the sperm are rendered lethal to the fertilized eggs. This sentences them to death. According to the study, this system cunningly increases the proportion of Wolbachia-infected offspring in the next generation because females with the bacteria successfully reproduce more frequently than females without.
Assistant Research Professor Rupinder Kaur explained, “The virus proteins control sperm by depleting the long non-coding RNAs required for normal sperm function.” The study used fruit flies with Wolbachia to establish a link between the bacteria and long non-coding RNA. Thus revealing a potential avenue for manipulating insect populations.
Consequently, this information can be used in various ways. For example, it can be used to control a population of pests that do not have the bacteria. In cases like this, scientists release males with Wolbachia to crash the population.
Going back to the bacteria’s medicinal benefits. Bordenstein said, “One of Wolbachia’s superpowers is that it blocks pathogenic RNA viruses. Some include Zika, dengue, and chikungunya virus. So mosquitoes with Wolbachia do not pass these viruses on to people when they bite.”
The researchers also believe this could have implications for addressing human sterility challenges. Kaur concluded, “We have reverse-engineered this process. We can fine-tune methods of population control with Wolbachia that are already in use.” The full details can be found in the Journal of Science.
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