In immunity studies, the interaction between host and pathogen has a profound effect on the outcome of an infection. Pathogen-associated molecular patterns (PAMPs), some common highly conserved molecular structures on the surface of pathogen, can be sensed and recognized by the host via pathogen recognition receptors (e.g., toll-like receptors).

The recognition helps host activate immune cells' signaling pathways, and modulate the immune responses of the host against the pathogen.

Indeed, there is fierce competition for trace elements and metabolic precursors between pathogen and host. Therefore, they share similar nutritional substrates and generate common metabolic products at the process of infection, which is called metabolic interaction.

Recently, Prof. YIN Yulong from the Institute of Subtropical Agriculture (ISA) of the Chinese Academy of Sciences, Prof. ZHU Guoqiang from Yangzhou University and Prof. DENG Jinping from South China Agricultural University illustrated that amino acids (AA) participate metabolic interaction between host and pathogen.

Some amino acids are pivotal to the competition between the host and pathogen, such as arginine, asparagine, and tryptophan. The key point is that the host supports defensive responses against pathogens and that depends on amino acids metabolism. The pathogens regulate AA metabolism and compete with the host for nutritional substrates.

"The host has the ability to alter AA metabolism after an infection by a pathogen," said REN Wenkai, a researcher of ISA, "Thus, AA influence immune responses of the host against a pathogen, such as the function of innate immune cells(e.g., macrophage), the activation and differentiation of T cells and the production of antibodies by B cells."

"Also, AA plays an important role in the physiology and virulence of pathogens. Thus, a change in AA metabolism at the site of infection will influence the outcome of an infection," REN said.

The research of AA-involved metabolic interaction between host and pathogen is beneficial to the treatment and prevention of epidemics, especially it will offer significant insight into pathogenic infections and reveal novel treatments to prevent and cure infections by modulating the abundance of AA or the metabolism of those AA.

Their study entitled "Amino Acids As Mediators of Metabolic Cross Talk between Host and Pathogen" was published in Frontiers in Immunology.

The research was supported by the National Key R & D Program, the National Natural Science Foundation of China, Key Programs of frontier scientific research of the Chinese Academy of Sciences, and the Priority Academic Program of Development Jiangsu High Education Institution.