Philadelphia - Several vaccines against the herpes simplex-2 virus, with which one in 10 sexually active adults are believed to be infected, and some of which suffer from recurrent genital exacerbations, have so far failed. Now US researchers seem to have more success with novel vaccine. Their nucleoside-modified mRNA vaccine, which uses technology from German company, protects mice and guinea pigs from genital herpes, according to report in Science Immunology (2019; doi:).
While several effective vaccines against the Varicella zoster virus, the development of vaccines against herpes simplex was more difficult. Large manufacturers such as GlaxoSmithKline (Herpevac, Simplirix) and Amgen (ImmunoVEX HSV2) have failed with their vaccines in clinical trials. Even smaller companies such as PaxVax and Genocea, which specialize in vaccine development, had to discontinue their projects after disappointing study results.
Now researchers in Philadelphia are presenting new vaccine candidate. The vaccine contains the messenger RNA for 3 proteins. As with DNA vaccines, the vaccinee's cells take over the production of the vaccine. This process can be accelerated by using messenger RNA, since, unlike in the case of DNA vaccines, the genes do not first have to be transcribed into the messenger RNA.
The development of mRNA vaccines took shape initially difficult because the molecules were unstable and vaccine production was ineffective. A process developed by the start-up company BioNTech from Mainz seems to have overcome this problem. Last October, there was research collaboration with the US researchers, which is apparently bearing fruit quickly.
The vaccine now presented contains, on the one hand, the mRMA for glycoprotein D, which the viruses need to enter the cells . The other two mRNA contain the information for 2 immune evasion molecules (glycoprotein C and glycoprotein E) with which the virus protects itself from attacks by the immune system.
The vaccines were initially tested on 64 mice, which were then infected with the herpes simplex-2 virus. As reported by the team led by Harvey Friedman from the Perelman School of Medicine, none of the animals developed genital herpes.
In 63 mice even “sterilizing” immunity was found: after 28 days there were no traces of the virus more detectable in the body of the mice. This immunity is important because, like all herpes viruses, the virus “hides” in the DNA of the spinal ganglia.
In phases of "careless" immune defense, exacerbations with painful blisters in the genital area then occur. The epithelial lesions also increase the risk of other sexually transmitted diseases such as HIV.
Ten guinea pigs were also successfully protected from infection with the vaccine. No animal developed genital lesions, the researchers found evidence of latent infection in only 2 animals.
According to Friedman, none of the previous vaccine candidates in the animal studies showed similarly good effect. The researchers hope to begin clinical studies soon.