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Wednesday, 8 May 2013

A vaccine for herpes? Researchers discover immune cells that suppress HSV-2 infection -

A vaccine for herpes? Researchers discover immune cells that suppress HSV-2 infection - 

Genital herpes is one of the most common types of sexually transmitted infections (STI) in the United States – as well as one of the most frustrating.  Characterized by periodic blisters on the genitals, rectum or mouth, there is currently no cure for the disease, and it can only be managed by antiviral medications which help shorten outbreak periods.
However, a new study may provide hope for those suffering from this STI. Researchers have identified a subtype of immune cells that suppress outbreaks of genital herpes caused by the herpes simplex virus type 2 (HSV-2).
The discovery could lead to a vaccine capable of preventing herpes lesions on people who have already contracted the STI – or in other words, a vaccine that could “clinically cure” an individual of herpes symptoms.
The newly identified T-cells, called CD8αα+ T-cells, reveal a great deal more information about genital herpes than was initially known.  
“What we found was that (these T-cells) are turned on and making all sorts of antiviral substances,” lead author Dr. Larry Corey, an internationally renowned virologist and president and director of the Fred Hutchinson Cancer Research Center in Seattle, Wash., told FoxNews.com.  “When the virus reactivates, they are the first cells in to contain the virus, and we showed they contain it very well. They can contain it before the virus escapes above the skin.”
Before this study, researchers believed that herpes reactivation was controlled at the ganglion level of the spinal canal area. But by using a technique called laser capture, Corey and his colleagues were able to biopsy and analyze the RNA in pieces of human tissue from the dermal-epidermal junction (DEJ), where the dermis – the outer layer of skin – connects to the epidermis – the layer of tissue just below the skin’s surface.  The team discovered that these CD8αα+ T-cells are located in the DEJ and are responsible for controlling HSV-2 – implying that herpes reactivation is controlled in the skin, not the spine.
Not only did the research team make this significant discovery about the T-cells’ location, they also found that the CD8αα+ T-cells are programmed to remain in the skin surrounding the genitals at all times – making them resident memory T-cells.  The cells’ long-term persistence may explain why patients have asymptomatic recurrences of genital herpes, because the cells are constantly doing “immune surveillance” – always working to find and destroy HSV-2.
“The real implication here is that the way herpes seems to act is that the virus is actually reactivating very frequently,” Corey said.  “The human immune response is containing it most of the time.”

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