Renal syndrome (HFRS) (肾综合征出血热).pptVIP

Herpse Viruses Xiao-Kui GUO Dept. of Microbiology and Parasitology BIOLOGICAL PROPERTIES Structure Composition Size: 150-200nm. Enveloped double stranded DNA viruses. Capsid: icosahedral symmetry and has 162 capsomeres. Nucleocapsid surrounded by an envelope contains viral glycoprotein spikes about 8 nm long. Genome: Large and encodes at least 100 different proteins. Classification Herpesvirus Replication Herpes Simplex Viruses Properties Belong to the alphaherpesvirus subfamily of herpesviruses Double stranded DNA enveloped virus with a genome of around 150 kb The genome of HSV-1 and HSV-2 share 50 - 70% homology. They also share several cross-reactive epitopes with each other. There is also antigenic cross-reaction with VZV. Man is the only natural host for HSV. Epidemiology (1) HSV is spread by contact, as the virus is shed in saliva, tears, genital and other secretions. By far the most common form of infection results from a kiss given to a child or adult from a person shedding the virus. Primary infection is usually trivial or subclinical in most individuals. It is a disease mainly of very young children ie. those below 5 years. There are 2 peaks of incidence, the first at 0 - 5 years and the second in the late teens, when sexual activity commences. About 10% of the population acquires HSV infection through the genital route and the risk is concentrated in young adulthood. Epidemiology (2) Generally HSV-1 causes infection above the belt and HSV-2 below the belt. In fact, 40% of clinical isolates from genital sores are HSV-1, and 5% of strains isolated from the facial area are HSV-2. This data is complicated by oral sexual practices. Following primary infection, 45% of orally infected individuals and 60% of patients with genital herpes will experience recurrences. The actual frequency of recurrences varies widely between individuals. The mean number of episodes per year is about 1.6. Epidemiology Worldwide in distribution. No animal reservoirs or vect