HOST-PARASITE RELATIONSHIP IN VIROLOGYThe competition for supremacy that takes place between the host and the parasite isreferred to as host-parasite relationshipAccordingly, the host may have the upper hand and remains healthy or loses thecompetition, and a disease develops.Human parasites are either unicellular (protozoa) or multicellular (helminthes andarthropods). The parasites may live inside the host (endoparasites) or on the hostsurface (ectoparasites).Viruses are unicellular and live inside the hostEndoparasites are classified into intestinal, atrial or they may inhabit body tissuescausing serious health problems. Ectoparasites are arthropods that either cause diseases, or act as vectors transmitting other parasites. Human evolution and parasitic infectionsViruses can invade the human body in different waysThrough oral routeThrough skinThrough sexual contact.InhalationBite by antropodsHost defense mechanisms consist of innate immunity which mediates initialprotection against infection and adaptive immunity which is more effective. Onceparasites have evaded innate host defenses, adaptive cellular and humoral immuneresponses are promoted against a wide array of antigenic constituents.Diagnosis of virologic diseases depends on several laboratory methods, imagingtechniques and endoscopy in addition to clinical picture and geographic location.Viral diseases may be presented by a wide variety of clinical manifestationsaccording to the tissue invaded.Direct microscopy is based on detection of the virus by examination ofdifferent specimens (stool, urine, blood, CSF and tissue biopsies)Immunodiagnostic techniques include antigen and antibody-detection assays.Molecular-based diagnostic approaches offer great sensitivity and specificity.Recently,
Nanotechnology can be applied as diagnostic procedures utilizingnanodevices. Control and prevention of viral diseases depend on the interactions among manyfactors such as the environment, the human behavior, and socio-cultural factors thatdetermine their transmission and persistence Viruses are an obligatory parasite that is completely dependent on its host and can’tsurvivePHAGE HOST RANGEThe host range of a bacteriophage is defined by what bacterial genera, species and strains itcan lyseIt is one of the defining biological characteristics of a particular bacterial virus. Because ofhost factors such as masking by O antigens that affects injection and the presence ofrestriction endonucleases, the relative efficiency of plating (EOP), that is, the titer of thephage on a given bacterial cell line compared to the maximum titer observed, may varyconsiderably.