— Smoking tobacco might be bad for your health, but a genetically altered version of the plant might provide a relatively inexpensive cure for the deadly rabies virus. In a new research report appearing in The FASEB Journal, scientists produced a monoclonal antibody in transgenic tobacco plants that was shown to neutralize the rabies virus. This new antibody works by preventing the virus from attaching to nerve endings around the bite site and keeps the virus from traveling to the brain.
"Rabies continues to kill many thousands of people throughout the developing world every year and can also affect international travelers," said Leonard Both, M.Sc., a researcher involved in the work from the Hotung Molecular Immunology Unit at St. George's, University of London, in the United Kingdom. "An untreated rabies infection is nearly 100 percent fatal and is usually seen as a death sentence. Producing an inexpensive antibody in transgenic plants opens the prospect of adequate rabies prevention for low-income families in developing countries." To make this advance, Both and colleagues "humanized" the sequences for the antibody so people could tolerate it. Then, the antibody was produced using transgenic tobacco plants as an inexpensive production platform. The antibody was purified from the plant leaves and characterized with regards to its protein and sugar composition. The antibody was also shown to be active in neutralizing a broad panel of rabies viruses, and the exact antibody docking site on the viral envelope was identified using certain chimeric rabies viruses. "Although treatable by antibodies if caught in time, rabies is bad news," said Gerald Weissmann, M.D., Editor-in-Chief of The FASEB Journal. "This is especially true for people in the developing world where manufacturing costs lead to treatment shortages. Being able to grow safe, humanized antibodies in genetically modified tobacco should reduce costs to make treatments more accessible, and save more lives."
"Rabies continues to kill many thousands of people throughout the developing world every year and can also affect international travelers," said Leonard Both, M.Sc
In this century, the number of human deaths in the United States attributed to rabies has declined from 100 or more each year to an average of 2 or 3 each year.
Early hepatitis B vaccination may be ineffective in teenagers
By Helen Albert, Senior medwireNews Reporter Research reveals that many infants who receive the complete series of hepatitis B virus (HBV) vaccinations have lost their protection by the time they reach adolescence. Li-Yu Wang (Mackay Medical College, New Taipei City, Taiwan) and colleagues found that by a mean age of 15.6 years, around 15% of those who received hepatitis B immunoglobulin (HBIG) after birth plus up to four doses of the hepatitis B vaccine tested positive for hepatitis B surface antigen (HBsAg), an early indicator of infection or carriage of HBV. The team found that significantly more (15-29%) children who received HBIG off schedule and whose mothers were persistently positive for HBsAg were positive for HBsAg themselves. "Chronic hepatitis B virus is a major health burden that leads to cirrhosis, liver cancer (hepatocellular carcinoma) and liver failure, shortening lives and placing a huge economic drain on society," commented Wang in a press statement. "While infantile HBV vaccination is highly effective, it is not 100% and our study examines the long-term success of the HBV vaccine in a high-risk population." Wang and team recruited 8733 Taiwanese high-school students born after July 1987 to take part in their study. All the students were tested for HBsAg and for antibodies to HBsAg (anti-HBs), the latter indicating prior vaccination or cleared HBV infection. Overall, around 87% of the cohort had records showing receipt of three or more doses of the HBV vaccine before the age of 3 years. Additional receipt of HBIG was documented in 381 children. Writing in Hepatology, the team reports that 1.9% of the overall cohort were HBsAg positive and 48.3% had anti-HBs. In children who received HBIG, the HBsAg positivity was 15%. Receiving less than the four recommended doses of the HBV vaccine was also associated with an increased risk for HBsAg positivity, with those receiving three and one/two doses having a 1.52- and 2.85-fold increased risk compared with those who had four doses. Wang and colleagues also note that of 1974 HBsAg-negative students who received a booster vaccination against HBV, those with anti-HBs titers of 1.0-9.9 mIU/mL prebooster achieved higher postbooster levels than those with prebooster anti-HBs titers below 1.0 mIU/mL. "For adolescents who lose protection, a HBV vaccination booster at age 15 or older should be considered, particularly in those born to HBsAg positive mothers or who had a high-risk of HBV exposure," conclude the authors.