Tips from the Journals of the American Society for Microbiology

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Public release date: 21-Jul-2008
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Contact: Carrie Slijepcevic
cslijepcevic@asmusa.org
American Society for Microbiology
Tips from the Journals of the American Society for Microbiology
Blue Light and Hydrogen Peroxide May Effectively Treat BiofilmsThat Cause Cavities and Gum Disease
Blue light commonly used by dentists to cure resin fillings andhydrogen peroxide (H 2 O 2 ) combined may be capable of reaching and treating bacteria in deeplayers of biofilms that can cause cavities and gingivitis. Theresearchers from Hebrew University, Hadassah, Jerusalem, Israel andthe University of California San Francisco report their findings inthe July 2008 issue of the journal Antimicrobial Agents and Chemotherapy .
Most bacteria in nature exist in communities of biofilms,structures that serve as physical barriers and severely limit theeffect of antibacterial agents. Oral biofilms are commonlyassociated with infections such as cavities, gingivitis andperiodontal disease. With antibiotic resistance continually on therise, researchers are exploring alternative sterilization methodsto effectively treat biofilms.
In the study biofilms of Streptococcus mutans were exposed towavelengths of visible light consisting of 400 to 500 nm for 30 to60 seconds while in the presence of 3 to 300 mM of hydrogenperoxide. Microbial counts from each treated sample were comparedwith those of the control and results showed that visible light andhydrogen peroxide combined successfully penetrated all layers ofthe biofilm creating an antibacterial effect.
"The ability of noncoherent visible light in combination with H 2 O 2 to affect bacteria in deep layers of the biofilm suggests thatthis treatment may be applied in biofilm-related diseases as aminimally invasive antibacterial procedure," say the researchers.
(D. Steinberg, D. Moreinos, J. Featherstone, M. Shemesh, O.Feuerstein. 2008. Genetic and physiological effects of noncoherentvisible light combined with hydrogen peroxide on Streptococcusmutans in biofilm. Antimicrobial Agents and Chemotherapy , 52. 7: 2626-2631.)
Rotavirus Infection May Accelerate Type 1 Diabetes in Mice
New research out of Australia suggests that rotavirus, a commonchildhood infection, may accelerate type 1 diabetes development inprediabetic mice. The findings are reported in the July 2008 issueof the Journal of Virology .
Type 1 diabetes is a common autoimmune disease that occurs wheninsulin-producing pancreatic cells are selectively destroyed.Rotaviruses are the major causative agents of severe, dehydratingdiarrhea in infants and children and they have been previouslyimplicated in the exacerbation of type 1 diabetes development.
Nonobese diabetic mice have been shown to develop a similar form ofautoimmune diabetes to that of human type 1 diabetes making them anideal model candidate. In the study nonobese diabetic mice up to 12weeks old were inoculated with murine rotaviruses and the rhesusmonkey rotavirus. Following infection results showed that diabetesonset was significantly accelerated. Researchers also observed thatexposure of nonobese diabetic mice to mouse rotavirus in a naturalexperiment also resulted in accelerated diabetes.
"These data provide the first evidence that rotavirus infection canaccelerate diabetes development in an animal model," say theresearchers.
(K.L. Graham, N. Sanders, Y. Tan, J. Allison, T.W.H. Kay, B.S.Coulson. 2008. Rotavirus infection accelerates type 1 diabetes inmice with established insulitis. Journal of Virology , 82. 13: 6139-6149.)
New Vaccine May Protect Against All Four Strains of Dengue Virus
Researchers from Maryland and South Carolina have developed a novelfour-component vaccine that protects monkeys against all fourstrains of dengue virus and may potentially offer protection to themillions of humans at risk worldwide. They report their findings inthe July 2008 issue of the Journal of Virology .
There are four distinct but similar strains of dengue virus causingmore than 100 million annual infections worldwide. Tropical regionsare at especially high risk where illness may range from mildsymptoms to potentially fatal forms of dengue hemorrhagic fever anddengue shock syndrome. With all four strains of the virus sharingsimilar clinical presentation, epidemiology, and distribution,development of a vaccine offering multi-faceted protection hasbecome a global health priority.
In the study researchers developed a tetravalent dengue virusvaccine by combining genes and proteins from all four dengue virustypes as well as incorporating an adenovirus agent. Followingintramuscular vaccination, rhesus macaques showed high antibodylevels that neutralized all four of the dengue virus types. Tofurther test the sustainability of the protective immune response,two separate live-virus challenges were administered at 4 and 24weeks after the final inoculation. Results showed completeprotection against dengue types 1 and 3 and significant protectionagainst types 2 and 4.
"Results reported here demonstrate that the tetravalent denguevaccine elicited a neutralizing antibody response to all fourdengue virus stereotypes and provided both short-term and long-termprotection against challenges from each of the four serotypes," saythe researchers.
(K. Raviprakash, D. Wang, D. Ewing, D.H. Holman, K. Block, J.Woraratanadharm, L. Chen, C. Hayes, J.Y. Dong, K. Porter. 2008. Atetravalent dengue virus vaccine based on a complex adenovirusvector provides significant protection in rhesus monkeys againstall four serotypes of dengue virus. Journal of Virology , 82. 14: 6927-6934.)