This contributes to the weakened immune response seen in those infected with EBOV.Endothelial cells may be infected within three days after exposure to the virus. The breakdown of endothelial cells leading to blood vessel injury can be attributed to EBOV glycoproteins. This damage occurs due to the synthesis of Ebola virus glycoprotein (GP), which reduces the availability of specific integrins responsible for cell adhesion to the intercellular structure and causes liver damage, leading to improper clotting. The widespread bleeding that occurs in affected people causes swelling and shock due to loss of blood volume. The dysfunctional bleeding and clotting commonly seen in EVD has been attributed to increased activation of the extrinsic pathway of the coagulation cascade due to excessive tissue factor production by macrophages and monocytes.After infection, a secreted glycoprotein, small soluble glycoprotein (sGP or GP) is synthesised. EBOV replication overwhelms protein synthesis of infected cells and the host immune defences. The GP forms a trimeric complex, which tethers the virus to the endothelial cells. The sGP forms a dimeric protein that interferes with the signalling of neutrophils, another type of white blood cell. This enables the virus to evade the immune system by inhibiting early steps of neutrophil activation. Immune system evasion
Filoviral infection also interferes with proper functioning of the innate immune system.
Hazeltons veterinary pathologist in Reston sent tissue samples from dead animals to the United States Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick, Maryland, where an ELISA test indicated the antibodies present in the tissue were a response to Ebola virus and not SHFV. An electron microscopist from USAMRIID discovered filoviruses similar in appearance, in crystalloid aggregates and as single filaments with a shepherds hook, to Ebola in the tissue samples sent from Hazelton Research Products Reston Quarantine Unit.A US Army team headquartered at USAMRIID euthanised the surviving monkeys, and brought all the dead monkeys to Fort Detrick for study by the Armys veterinary pathologists and virologists, and eventual disposal under safe conditions. Blood samples were taken from 178 animal handlers during the incident. Of those, six animal handlers eventually seroconverted, including one who had cut himself with a bloody scalpel. Despite its status as a Level‑4 organism and its apparent pathogenicity in monkeys, when the handlers did not become ill, the CDC concluded that the virus had a very low pathogenicity to humans.The Philippines and the United States had no previous cases of Ebola infection, and upon further isolation, researchers concluded it was another strain of Ebola, or a new filovirus of Asian origin, which they named Reston ebolavirus (RESTV) after the location of the incident. Reston virus (RESTV) can be transmitted to pigs. Since the initial outbreak it has since been found in nonhuman primates in Pennsylvania, Texas, and Italy, where the virus had infected pigs.