The chikungunya-specific upstream components of the type-1 interferon pathway involved in the hosts response to chikungunya infection are still unknown. Nonetheless, mouse studies suggest that IPS-1 is an important factor, and that IRF3 and IRF7 are important in an age-dependent manner. Mouse studies also suggest that chikungunya evades host defenses and counters the type-I interferon response by producing NS2, a nonstructural protein that degrades RBP1 and turns off the host cells ability to transcribe DNA. NS2 interferes with the JAK-STAT signaling pathway and prevents STAT from becoming phosphorylated.In the acute phase of chikungunya, the virus is typically present in the areas where symptoms present, specifically skeletal muscles, and joints. In the chronic phase, it is suggested that viral persistence (the inability of the body to entirely rid itself of the virus), lack of clearance of the antigen, or both, contribute to joint pain. The inflammation response during both the acute and chronic phase of the disease results in part from interactions between the virus and monocytes and macrophages. Chikungunya virus disease in humans is associated with elevated serum levels of specific cytokines and chemokines. High levels of specific cytokines have been linked to more severe acute disease: interleukin-6 (IL-6), IL-1β, RANTES, monocyte chemoattractant protein 1 (MCP-1), monokine induced by gamma interferon (MIG), and interferon gamma-induced protein 10 (IP-10). Cytokines may also contribute to chronic Chikungunya virus disease, as persistent joint pain has been associated with elevated levels of IL-6 and granulocyte-macrophage colony-stimulating factor (GM-CSF).
Char syndrome is an autosomal dominant congenital disease caused by mutations in TFAP2B gene which affects the development of the bones of the face as well as the heart and limbs. During embryo development, TFAP2B regulates the production of the protein AP-2β, a transcription factor that is active in the neural crest and helps regulate genes that control cell division and apoptosis. There are at least 10 mutations of this gene that have been identified in people presenting Char syndrome, which alters specific regions of the gene preventing production of the transcription factor and disrupting normal development of embryo structures. People with this condition present a very distinct facial appearance with flattened cheek bones, flat and broad tip nose, shortened distance between the nose and upper lip, triangular-shaped mouth with tick lips and strabismus. It is also characterized by a patent ductus arteriosus, which is the failure to close the ductus that connects the aorta and pulmonary artery during pre-birth life and may cause many symptoms including breathing issues and heart failure. Abnormalities of hand and finger development have also been reported in people with this condition, including short or absent fifth finger. Other abnormal findings include supernumerary nipples. These conditions often affect multiple members of a family and there are no reports of non-genetic factors that might be related with incidence of this syndrome. It was first described by Florence Char in 1978. == References ==