Substance in human sperm inhibits certain viruses

Human sperm inhibits Zika, Dengue and West Nile viruses

In a man infected with Zika virus, the sperm contains up to one hundred million Zika viruses. Nevertheless, the risk of sexual transmission is relatively low. The virus is transmitted in most cases by mosquitoes. An international research team investigated why Zika is not so well transmitted via semen and found out that certain substances in the sperm inhibit Zika viruses. So-called vesicles are responsible for the effect. These are small bubbles surrounded by a membrane. They make it more difficult for viruses to dock with other cells.

These results are from a recent study by the research team led by the virologist Professor Jan Münch from the University of Ulm. In earlier work, sperm had already attracted attention by its antimicrobial effect. The scientists have now clarified how the seminal fluid inhibits the Zika virus and which biochemical components are responsible for these effects. The study results were recently published in the journal "Nature Communications".

Sperm has a big impact on the transmission of sexual diseases. While it increases the risk of infection in some diseases, reduces sperm in other diseases such as Zika transmission risk. (Image: Christoph Burgstedt / fotolia.com)

Sperm as natural protection from Zika

"We were very surprised when we found out that the sperm inhibits infection by the Zika virus and not - as in HIV-1 - even further amplified," explains the first author of the study. Janis Müller in a press release on the study results. The researchers showed that the virus could spread less by the sperm in the vaginal and anal tract as well as in the uterus.

Sperm affects the portability of sexual diseases

"The seminal fluid is rich in bioactive substances," reports Sudienleiter Münch. These include, for example, proteins, enzymes, cytokines, hormones and ions. These can affect the vaginal milieu, which in turn affects the portability of sexual diseases. In HIV viruses, the risk of transmission through the sperm increases, with Zika viruses it sinks.

Where does the protective effect against Zika, Dengue and West Nile viruses come from?

"Extracellular vesicles, which are abundant in sperm, reduce the attachment of viruses to the cells and thus prevent the infection," explains Münch. The vesicles are vesicular particles that are abundant in sperm. They are responsible for the storage and transport of certain substances at the cellular level. The same protective effect has also been seen with dengue and West Nile viruses, which can cause dangerous tropical diseases. With the knowledge gained can be explained, why it comes in spite of large amounts of virus particles in the sperm rarely sexual transmission of Zika, the researchers said.

Do not give up on condoms

Although semen may provide some protection against these diseases, the researchers warn not to do without condoms. If you are traveling to Zika danger areas, you should protect yourself against mosquitoes and use a condom during sex. Not least because many other sexual diseases such as HIV can be transmitted via unprotected sexual intercourse.

Protection against mosquito bites

The Aedes mosquitoes is considered the number one infection preventer in Zika, Dengue and West Nile viruses. Recent studies by another research group have shown that this type of mosquito is also increasingly spreading in Europe and tropical diseases such as yellow fever, dengue and Zika are also conceivable in Germany.

About Zika

The Zika virus is mainly distributed in Central and South American countries and the Pacific Islands. Although infection is usually not fatal, it can trigger severe courses of meningitis. Pregnant women, in particular, have to be wary of the virus because there is an association between the infection and skull malformations. For example, unborn babies may be affected by microcephaly, in which the embryos develop a very small head. (Vb)