Sunday, 26 February 2017

Bacteria turn a tick's gut microbes against itself


Before infecting humans, tick-borne bacteria or viruses first have to get past a tick's defenses to colonize it. How this occurs is not well understood. To investigate, Yale researchers studied a model of the second-most-common tick-borne infection in the United States, human granulocytic anaplasmosis, which can cause headaches, muscle pain, and even death.

The researchers found that in ticks, the bacterium that causes the infection, A. phagocytophilum, triggers the expression of a particular protein. This protein alters molecules in the tick's gut, allowing the bacteria to enter and colonize the gut microbes.

Anaplasma phagocytophilum (formerly Ehrlichia phagocytophilum) is a gram-negative bacterium that is unusual in its tropism to neutrophils. It causes anaplasmosis in sheep and cattle, also known as tick-borne fever andpasture fever, and also causes the zoonotic disease human granulocytic anaplasmosis

"It's like a stealth warrior that indirectly changes the tick by using the tick's own defense system," said Erol Fikrig, M.D., chief of the Infectious Diseases Section at Yale School of Medicine and senior author of the study.

The unexpected finding could help scientists develop strategies to block A. phagocytophilum and other tick-borne agents that cause disease, say the researchers. Fikrig's team will explore the phenomenon in the bacterium that causes Lyme disease, and its work could have implications for other mosquito-borne infections, such as Zika and West Nile.

See:

Nabil M. Abraham, Lei Liu, Brandon Lyon Jutras, Akhilesh K. Yadav, Sukanya Narasimhan, Vissagan Gopalakrishnan, Juliana M. Ansari, Kimberly K. Jefferson, Felipe Cava, Christine Jacobs-Wagner, Erol Fikrig. Pathogen-mediated manipulation of arthropod microbiota to promote infection. Proceedings of the National Academy of Sciences, 2017; 201613422 DOI: 10.1073/pnas.1613422114

Posted by Dr. Tim Sandle