Clinical trials – edible vaccines – part 3

a.Rabies

Tomato plants expressing rabies antigens could induce antibodies in mice. Instead, TMV (Tobacco Mosaic Virus) may also be used. Transformed tomato plants using CaMV (Cauliflower Mosaic Virus) with the glycoprotein (G-protein) gene of rabies virus (ERA strain) were shown to be immunogenic in animals.

Scientists at the University of Agricultural Sciences (UAS), Bangalore, have also developed an edible vaccine for rabies. The vaccine can be injected into musk melons, lettuce and other vegetables. UAS has received a pre-patent and is awaiting a patent, according to Dr T.K. Siddarame Gowda, Head, Biotechnology Department. He said tests have been completed on mice at the National Institute of Mental Health & Neuro Sciences (NIMHANS), the country's only accredited centre for research on rabies vaccine.

Found this excellent link http://www.epi.state.nc.us/epi/rabies/orv2.html

b.HIV

Initial success in splicing HIV protein into CPMV(Cow Pea Mosaic Virus) has been achieved. Two HIV protein genes and CaMV as promoter were successfully injected into tomatoes with a needle and the expressed protein was demonstrable by polymerase chain reaction (PCR) in different parts of the plant, including the ripe fruit, as well as in the second-generation plant.

Dr. Shchelkunov's laboratory teamed up with other Russian scientists from both the Novosibirsk Institute of Biological Chemistry and Basic Medicine, and the Siberian Institute of Plant Physiology and Biochemistry in Irkutsk, Russia. To introduce the HIV gene into tomatoes, these Russian scientists took advantage of a naturally occurring bacterium to introduce foreign DNA into many different plant genomes including tomatoes. Scientists then applied PCR (polymerase chain reaction) technology to confirm the presence of the HIV gene in the transgenic plants. Other techniques were also used to confirm that the correct HIV protein was being made in different parts of the transgenic plants including and most importantly the ripe fruit of the tomato plants.

Of course, the work was not cut out for them; the researchers had to check whether the HIV gene was inherited by subsequent generations of plants. To do this they took seeds from transgenic tomatoes, let them germinate and grew a second generation of transgenic tomatoes, which also proved to contain the HIV gene and antigen protein just as their parent plants had.

Also check out: http://www.newscientist.com/article/dn2161-edible-hiv-vaccine-breakthrough.html

c.STDs

HPV is the cause for cervical cancer. Human papilloma virus type-11 (HPV-11) recombinant VLPs produced in insect cells are immunogenic when given orally to mice. The response is dose-dependent and genotype-restricted. Thus, VLPs may be effective oral immunogens for the prevention of anogenital HPV disease.

References: a.http://www.thehindubusinessline.com/2002/06/13/stories/2002061301181700.htm

b. http://www.news-medical.net/?id=4971

c. Lal P, Ramachandran VG, Goyal R, Sharma R. Edible vaccines: Current status and future. Indian J Med Microbiol [serial online] 2007 [cited 2008 May 2];25:93-102. Available from: http://www.ijmm.org/text.asp?2007/25/2/93/32713