What is the basic structure of a virus ? •Basic structure consists of &bull

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(1)Prof. Md. Akram Hossain May, 2011.

(2) What is a virus? Smallest obligate intracellular microbe (20-40 nm) possessing one type of NA in the genome encased in a shell of protein capsid.. What is the basic structure of a virus ? •Basic structure consists of • Genome - RNA or DNA •Capsid - Polypeptide •Envelope - Lipid ( some) Prof. Muhammad Akram Hossain. Virology Review. 2.

(3) Lab Dx of Viral diseases Principle: Virtually all viral diseases are diagnosed by serological tests for antibody against the virus. In few cases antigens are also detected. IgM indicates recent infection and if facilities not available rising titer for IgG is also helpful. Electron Microscopy is also done in reference lab. Cell culture is done for research purpose. NA based techniques are used in special cases.. Steps: Specimen : Mostly serum other. specimens according to. site of infection. M/E : Light microscopy is rarely helpful, E/M can be done where available.. Isolation in cell culture : done for research purpose. Immunological tests: mostly for Ab e.g. Anti HAV, Anti HCV, Anti Dengue, Anti rubella etc. Prof. Muhammad Akram Hossain. Virology Review. 3.

(4) How can you diagnose viral infection in the lab? Principle : Isolation of virus or demonstration by E/M or F/M, detection of Antibody, antigen or NA. Practically detection of antibody is widely used .. Steps: Collection of specimen – according to site of infection & blood for serology. Tests Cytologic examination Electron / Immune electron microscopy Virus isolation or growth Detection or viral antigens or enzymes Detection of viral genome Detection of antibodies ( serology) (most important) Prof. Muhammad Akram Hossain. Virology Review. 4.

(5) Terminology for virus components CAPSID is the protein coat that encloses the nucleic acid CAPSOMERS are structural units that are building units of the capsid NUCLIEC ACID is the DNA or RNA making up the genome inside the capsid ENVELOPE encloses the capsid VIRION is the complete infective virus particle Prof. Muhammad Akram Hossain. Virology Review. 5.

(6) How can You classify viruses? Viruses can be classified on the following basis •Type of NA in the genome -. RNA or DNA. •Strand of NA - DS or SS •Presence of envelope -Enveloped or Non enveloped •Character of NA- positive / negative strand •Symmetry of genome - Icosahedral, Helical Prof. Muhammad Akram Hossain. Virology Review. 6.

(7) Replication strategies of human virus families. Prof. Muhammad Akram Hossain. Virology Review. 7.

(8) PRION (proteinacious infectious agent): Hypothesized identity of the unconventional slow viruses (such as the Kuru, Scrapie and “Mad cow” disease agents). No nucleic acid is known to be required for prion function. They are thought by many to consist solely of protein and perhaps lipids. Study of these agents has resulted in 2 nobel prize awards.. Prof. Muhammad Akram Hossain. Virology Review. 8.

(9) Prof. Muhammad Akram Hossain. Virology Review. 9.

(10) What are the differences between virus and prion? Write down the steps of viral replication.. Prof. Muhammad Akram Hossain. Virology Review. 10.

(11) PRION (proteinacious infectious agent): No nucleic acid. They are thought by many to consist solely of protein and perhaps lipids. Viruses – consists of nucleic acid core of either DNA or RNA with a protein capsid.. Prof. Muhammad Akram Hossain. Virology Review. 11.

(12) What is the Principle of viral replication? Principle of viral replication. consists of. • Replication of the genome - by transcription •Synthesis of structural proteins & enzymes- by translation What are steps of viral replication? Steps are• Adsorption •Penetration •Uncoating •Genome replication •Assembly and release of progeny virus Prof. Muhammad Akram Hossain. Virology Review. 12.

(13) Principle of diagnosis Lab Dx of Microbial diseases. Demonstration of causative agents by microscopy commonly practiced for parasitic diseases & fungal diseases Isolation and identification of causative agent by artificial culture - (C/S) commonly practiced for bacterial diseases. Detection of antibody or antigen from blood or other body fluids practiced for viral diseases & some bacterial & parasitic diseases Detection of Nucleic acid segment (DNA or RNA) Prof. Muhammad Akram Hossain. Virology Review. 13.

(14) How a virus comes out of host cell? Budding – No cell destruction, slow release, may form envelope (most RNA) Cell Lysis – Spontaneous release of mature and complete viral particles. (more characteristics of DNA viruses). Prof. Muhammad Akram Hossain. Virology Review. 14.

(15) ‘Budding’ HIV leaving the infected T-cell. Prof. Muhammad Akram Hossain. Virology Review. 15.

(16) What are the early and late proteins? Early proteins are those proteins which are synthesized before the replication of the DNA genome. They help in genome replication and not found in the virion structure. Late proteins are those proteins which are synthesized after the replication of the DNA genome. They are incorporated in the virion structure.. Prof. Muhammad Akram Hossain. Virology Review. 16.

(17) Antiviral immune response Antiviral immune response consists of Innate or nonspecific & Acquired or specific. Innate Interferones Natural killer cells (NK cells) Monocytes / Macrophages. Acquired T- cell response ( CD8 cells or cytotoxic T cells) Antibody - IgM, IgG, IgA Neutralization Opsonization ADCC Block attachment. Prof. Muhammad Akram Hossain. Virology Review. 17.

(18) Escape of a virus from immune response Escape recognition of virus Direct cell to cell spread Changing antigenicity e.g HIV. Inactivate immune response Killing cells of immune system -e.g. HIV - CD4 CD4 cells Interfere with inteferron activity Inactivate complement. Block immune response Producing competing antigen e.g. HBsAg. Prof. Muhammad Akram Hossain. Virology Review. 18.

(19) Effects of virus on host cells Cytolytic infection -Host cell death Persistent infection - little or no change in cell Latent infectioninfection- no replication of virus Immortalization - enhances host cell growth Abortive infection - Little or no effect Non permissive host Defective virus Death of host cell before replication Prof. Muhammad Akram Hossain. Virology Review. 19.

(20) Various effects of viruses on infected cells.. HTLV. HIV. EBV Prof. Muhammad Akram Hossain. HAV Virology Review. HBV. HPV 20.

(21) Between Enveloped & Non enveloped virus Which one is more tough? Non--enveloped viruses are more tough Non – They are relatively stable and resistant to environment insult i.e. they can resist desiccation, dry heat and soap – They generally kill the cells they infect as part of their life cycle i.e. cell lysis. Enveloped viruses are soft – The envelope is relatively sensitive to desiccation, dry heat and detergents – Can shed from infected cells in long term chronic infection.. This is called budding infection – Envelopes are usually derived from the host cell membrane Prof. Muhammad Akram Hossain. Virology Review. 21.

(22) Helical. Prof. Muhammad Akram Hossain Virology Review. 22.

(23) What are the steps Viral pathogenesis?. 1. Entry and primary replication 2.Viral spread and cell tropism 3. Cell injury and clinical illness 4. Recovery from infection. 5. Virus shedding.. Prof. Muhammad Akram Hossain. Virology Review. 23.

(24) Compare and contrast between hepatitis B virus and hepatitis C virus. virus. Write down the seromarkers of hepatitis B virus with interpretation.. interpretation. Prof. Muhammad Akram Hossain. Virology Review. 24.

(25) What are the hepatitis viruses ? Classical or Primary – – – – – –. HAV HBV HCV HDV HEV HGV. Secondary or other viruses infecting liver – Yellow fever virus, CMV, EBV, Herpes simplex virus, rubella virus, some enteroviruses Prof. Muhammad Akram Hossain. Virology Review. 25.

(26) The Hepatitis B Virus Prof. Muhammad Akram Hossain. Virology Review. 26.

(27) What is the mode of infection for HBV? Hepatitis B DNA is found in most bodily fluids - serum, menstrual blood, saliva, semen, and urine 100x more infective than HIV; 10x more infective than HCV Can last outside the human body for up to a week. Possible methods of transmission: Mother to infant at the time of birth Sexually Parenteral drug use Shared utensils: razors, toothbrushes, etc. Unsterile instruments: tattoo needles, dental equipment, etc. Needle stick Prof. Muhammad Akram Hossain Virology Review. 27.

(28) Which hepatitis viruses are transmitted by faeco--oral route and which are by parenteral faeco route – HAV & HEV are transmitted by faeco faeco--oral route and HBV, HCV, HDV by parenteral route route... Vaccine are available for which Hepatitis viruses? – HAV & HBV. Which hepatitis viruses leads to chronicity & complications? – – – –. HBV –(> (>95 95% % ) in infants and <05% 05% in adults HCV - about 50% 50% cases HDVHDVHEV – 1-2% in common population and 20% 20% pregnant women. women. Prof. Muhammad Akram Hossain. Virology Review. 28.

(29) What is the Outcome of HBV infection in adults – Recovery and immune to next infection 90 - 95% 95% – Persistent infection Asymptomtic carrier 10 -15% 15% Chronic persistent hepatitis – Clearance – Chronic active hepatitis Cirrhosis of liver Hepatocellular carcinoma. – Death due to fulminant hepatitis 1% Prof. Muhammad Akram Hossain. Virology Review. 29.

(30) Hepatitis D (Delta) Virus δ antigen. HBsAg. RNA Prof. Muhammad Akram Hossain. Virology Review. 30.

(31) What is the Treatment and prevention of HBV? – Alpha interferon – Lamivudin (nucleoside analog) – Active immunization by Component vaccine (HBsAg) – passive immunization by hyperimmunoglobulin – Post exposure vaccine (passive(passive-active immunization) Prof. Muhammad Akram Hossain. Virology Review. 31.

(32) What are the serological markers of HBV infections which one indicates active replication and which one alone can be used as surest test for active infection?. HBsAg, HBsAb HBe Ag, HBeAb HB cAb HBeAg in blood indicates replication of the virus HBcAb IgM can alone used as marker of active infection infection.. Prof. Muhammad Akram Hossain. Virology Review. active surest. 32.

(33) What is the significance of HBsAg and HBsAb – HBsAg is present active, chronic and convalescent carriers. carriers. HBsAb is present in persons with immunity following infection or vaccination.. vaccination. Which markers are present in window and which are absent in window period? Only HBcAb IgM present during window period.. Prof. Muhammad Akram Hossain. Virology Review. 33.

(34) Window period. HBsAg - ; Anti Anti--HBs - ; Anti--HBc +, IgM Anti predominant. Prof. Muhammad Akram Hossain. Virology Review. 34.

(35) What are the important properties and clinical significance of HDV •Defective RNA virus( incomplete virus ) • HDV uses the surface antigen of HBV as its envelop protein • causes chronic hepatitis when infected with HBV •Co-infection increases severity of HBV •Superinfection leads to fulminant hepatic failure. Prof. Muhammad Akram Hossain Review •Can be treated with alphaVirology interferon.. 35.

(36) Hepatitis D - Clinical Features Coinfection –severe acute disease. –low risk of chronic infection. Superinfection –usually develop chronic HDV infection. –high risk of severe chronic liver disease. –may present as an acute hepatitis. Prof. Muhammad Akram Hossain. Virology Review. 36.

(37) What are the important properties and clinical significance of HCV Enveloped RNA virus, transmitted by parenteral route. 3% of world population infected 170 million chronic carrier worldwide strongly predisposes to hepatocellular carcinoma(HCC) causes chronic infection 75% chronic active hepatitis and cirrhosis occurs in 10% of these. Can be diagnosed by Antibody detection by ELISA RIBA ( recombinant immunoblot assay) PCR. Can be treated by alpha interferon and ribavirin Pegylated interferon. There is no vaccine Prof. Muhammad Akram Hossain. Virology Review. 37.

(38) What is Natural course of HCV?. Hepatitis antibody positive 70-85% HCV +:. 15-30% clear. chronic infection. the virus. 10-20%. 80-90%. serious liver disease. asymptomatic-moderate disease. 1-4%/yr HCC Prof. Muhammad Akram Hossain. Virology Review. 38.

(39) Difference between HBV &HCV HBV Possess RT enzyme. HCV RNA virus, SS Does not possess RT. Mostly symptomatic. Mostly asymptomatic. Chronicity 5% in adults and 90% in infants. Chronicity in 5050-75%. Complications less. Complications more. Lab diagnosis easy. Difficult. Vaccine available. No vaccine. DNA virus, DS (incomplete). More infective (10X more HCV) Less infective Prof. Muhammad Akram Hossain Virology Review. 39.

(40) Hepatitis viruses Ques: what are the classical hepatitis viruses? Ans: HAV, HBV, HCV, HDV, HEV, HGV Ques: How can you diagnose a case of acute HBV infection? Ans: By detecting anti HBcIgM Ques: What are the serological markers of HBV infection? Ans: HBsAg, AntiHBs, HBeAg, AntiHBe, anti HBc Ques: Which marker indicates infectivity of HBV infection? Ans: HBeAg Ques: Which marker indicates carrier state of HBV infection? Ans: HBsAg Ques: Which marker indicates immunity state of HBV infection? Ans: Anti HBs Prof. Muhammad Akram Hossain. Virology Review. 40.

(41) Virus causing perinatal infection Rubella virus Cytomegalo virus Herpes simplex viris Varicella zoster virus Hepatitis B virus Entero virus HIV Parvovirus Measles Mumps Prof. Muhammad Akram Hossain. Virology Review. 41.

(42) Prof. Muhammad Akram Hossain. Virology Review. 42.

(43) HIV.

(44) Give the laboratory diagnosis of HIV infection in adults. Prof. Muhammad Akram Hossain. Virology Review. 44.

(45) How HIV infection is diagnosed? Principle:: For practical purpose detection of antibody Principle is widely used, other methods include Ag detection, virus isolation, CD4 count & RT-PCR Steps: 1. Virus isolation isolation:: PBMC grow slowly takes 7-14 days 2. Serology Serology:: Ab by ICT & ELISA and confirmed by Western blot, & Line immunoassay 3. Detection of viral Antigen : p24 Ag By ELISA 4. Detection of viral nucleic acid : Molecular based test ( RT RT--PCR, bDNA) are very sensitive and measures viral load Prof. Muhammad Akram Hossain. Virology Review. 45.

(46) What is HIV and AIDS? How dangerous it is for the mankind? – AIDSAIDS- stands for Acquired immunodeficiency syndrome, a disease syndrome caused by HIV HIV.. – HIV – stands for Human immune deficiency virus. Since discovery in 1986 1986,, 62 million infected and of them 20 million died died.. It is called plague of 2oth century century.. In Bangladesh 248 reported HIV cases since the first detection in 1989 of which 26 developed AIDS of which 20 died and mostly from tuberculosis. Prof. Muhammad Akram Hossain. Virology Review. 46.

(47) What are important properties of HIV? – RNA retro virus, has double copy of the genome (Diploid) possess reverse transcriptase, and is enveloped virus. virus. Why it is called retrovirus and How it causes immuno deficiency? – It is called retrovirus because from RNA genome by reverse transcriptase enzyme proviral DNA is formed from which again genomic RNA forms forms.. – It infects helper T lymphocyte (L tropic), Macrophage & monocyte (M tropic) and destroys them thereby both CMI & antibody mediated immunity are hampered.. hampered Prof. Muhammad Akram Hossain. Virology Review. 47.

(48) How a AIDS patient dies? – Aids patients dies due to opportunistic infections by Protozoa: Cryptosporidium parvum, Toxoplasma gondii, Isospora belli Fungi: candida albicans, Pneumocystis carinii Bacteria: Myco. Avium Intracellulare, M Tuberculosis, Salmonella, Nocardia Viruses: CMV, HSV, VZV, Adenovirus, HBV. Prof. Muhammad Akram Hossain. Virology Review. 48.

(49) Transmission of HIV HIV is not transmitted by • Coughing, sneezing • Insect bites • Touching, hugging • Water, food • Kissing. • Public. baths • Handshakes • Work or school contact • Using telephones • Sharing cups, glasses, plates, or other utensils. Prof. Muhammad Akram Hossain. Virology Review. 49.

(50) Natural History of HIV Infection. Prof. Muhammad Akram Hossain. Virology Review. 50.

(51) Prevention, treatment & control Antiviral drugs:RT inhibitor & protease inhibitors. HAART therapy Mutates rapidly, so no vaccine available Control measures: Bangladesh is still fortunate to be a low prevalence country. Prof. Muhammad Akram Hossain. Virology Review. 51.

(52) Prof. Muhammad Akram Hossain. Virology Review. 52.

(53) What are peculiarities / special properties of Herpes viruses? Name the members HERPES” Greek word means creep or crawl.. DNA, DS Enveloped virus Latent and recurrent infections Multinucleated giant cells with inclusion bodies formed. CMI is required for control, if CMI is lowered, severe infections develop (Opportunistic infections) Members are 1. Herpes simplex -1 (HSV-1) 2. Herpes simplex -2 (HSV-2) 3. Varicella -Zoster (VSV -HHV-3) 4. Cytomegalo virus ( CMV or HHV -5) 5. Human herpes virus -6 (HHV-6) 6. Human herpes virus -7 (HHV-7) 7. Epstein -Barr virus (EBV or HHV-4) Prof. Muhammad Akram Hossain. Virology Review. 53.

(54) Classification of herpesviruses . Three subfamilies:. Alphaherpesviruses - HSV-1, HSV-2, VZV Betaherpesviruses - CMV, HHV-6, HHV-7 Gammaherpesviruses - EBV, HHV-8 .. Prof. Muhammad Akram Hossain. Virology Review. 54.

(55) What diseases are caused by HSV-1 & 2 HSV-1 (usually above the Waist) Gingivostomatitis Keratitis Encephalitis. HSV-2 (usually below the waist) Genital herpes Neonatal herpes Disseminated CNS, Eye, Skin. Prof. Muhammad Akram Hossain. Virology Review. 55.

(56) What diseases are caused by CMV & EBV CMV Asymptomatic Congenital CMV mononucleosis Reactivation in AIDS patients Retinitis, Pneumonia, Eosophagitis Disseminated infections.. EBV Infectious mononucleosis Burkitt’s lymphoma Nasopharyngeal carcinoma. Prof. Muhammad Akram Hossain. Virology Review. 56.

(57) Cytomegalovirus it can be transmitted vertically or horizontally usually with little effect on the host. Transmission may occur in utero, perinatally or postnatally. Once infected, the person carries the virus for life which may be activated from time to time,. Reactivation can also lead to vertical transmission. It is also possible for people who have experienced primary infection to be reinfected with another or the same strain of CMV, this reinfection does not differ clinically from reactivation. . In developing countries, over 90% of people are ultimately infected. Prof. Muhammad Akram Hossain. Virology Review. 57.

(58) Which virus is the most common cause of viral diarrhea? What are its peculiarities? Rotavirus is the commonest cause of viral diarrhea causing death of 870000 children in the world per year. 27,000 children die every year in Bangladesh Rotavirus is the only double stranded RNA virus,. Segmented (11), Double shell. belongs to family REO virus (Respiratory Enteric Orphan), its shape is like a wheel (rota) so it is named as rotavirus. What are the other causes of viral diarrhea? Adeno virus, Calcivirus, Norwalk virus, Astrovirus Prof. Muhammad Akram Hossain. Virology Review. 58.

(59) What are mechanisms involved in rotaviral diarrhea? How it is diagnosed? Three mechanisms are involved It infects the epithelial cells of the small intestine and multiplies in the tip of the villi resulting in death and desquamation. There is reactive hyperplasia of the crypt cells. These two effect is responsible for decreased absorption of fluids and nutrients and increased secretion of fluids. A third mechanism is also involved – a viral protein stimulates the nervous system of the intestine that causes increased secretion. Regeneration of villi occurs in 1 week time Prof. Muhammad Akram Hossain. Virology Review. 59.

(60) How can you diagnose rota viral diarrhea ?. Principle Detection of viral particles or its antigen excreted in the stool is the basis of diagnosis because about 1011/ml of virus particles are present in diarrhoeal stool.. Specimen Stool, Rectal swab. Detection of viral antigen Latex agglutination, Co-agglutination, or Particle agglutination tests are available.. Detection of viral NA PAGE (polyacryl amide gel electrophoresis). M/E Electron microscopy or immune electron microscopy rarely used. Prof. Muhammad Akram Hossain. Virology Review. 60.

(61) What are the myxo viruses? Why they are so called? Influenza virus (Orthomyxoviruses) Parainfluenza, Measles, Mumps, Respiratory syncytial virus (RSV) (Paramyxoviruses) They are called myxo viruses because they can attack mucin layer (‘Myxo’ – means mucins ). These enveloped RNA viruses have got either Hemagglutinin, Neuraminidase, or Fusion proteins on their surface. Orthomyxovirus are segmented without fusion proteins whereas Paramyxoviruses are non-segmented with fusion proteins.. Prof. Muhammad Akram Hossain. Virology Review. 61.

(62) What do you mean by antigenic shift and antigenic drift? Write short note on H5N1.. Prof. Muhammad Akram Hossain. Virology Review. 62.

(63) What is antigenic drift and antigenic shift? What is its clinical significance?. Antigenic shift – major change in the structure of HA occurs only in Influenza A virus. It occurs in every 10 -11 years intervals. Antigenic drift – minor change in the structure of HA occurs both Influenza A & B virus. It occurs in every years. Vaccine development is very difficult due this antigenic shift and drift.. Prof. Muhammad Akram Hossain. Virology Review. 63.

(64) What is avian influenza? The disease in birds Avian influenza is a disease of birds. Occurs worldwide. Caused by type A strain of influenza virus 1st identified > 100yrs ago in Italy All bird species are susceptible, some more resistant than others 16 subtypes of influenza virus are known to infect birds Prof. Muhammad Akram Hossain. Virology Review. 64.

(65) 2- What is an avian influenza A virus (H5N1) ? H5N1 virus – is an influenza virus subtype that occurs mainly in birds. Like all bird flu viruses, H5N1 circulates among birds worldwide. It is very contagious among birds, & can be deadly. Prof. Muhammad Akram Hossain. Virology Review. 65.

(66) Avian H5N1 is a strain with pandemic potential. It might adapt among humans & becomes contagious i.e. becomes a human infective virus. The human immune system will have no pre--existing immunity to the new virus. pre People who catch the infection will have a more serious disease than that caused by normal influenza. Prof. Muhammad Akram Hossain. Virology Review. 66.

(67) 3- Why is H5N1 of particular concern? - It mutates rapidly & seems to acquire genes from viruses infecting other animal species. species. - It can cause severe disease in humans humans.. - Birds that survive infection excrete virus for 10. days (orally & in faeces) helping in the spread spread.. - The more birds get infected, the greater the opportunity for direct infection of humans humans.. Prof. Muhammad Akram Hossain. Virology Review. 67.

(68) Pandemic Reassortment in human H5N1. Prof. Muhammad Akram Hossain Virology Review. Source: WHO/WPRO. 68.

(69) Congenital Rubella Syndrome Infection. may. affect. all. organs. May lead to fetal death or premature delivery Severity of damage to fetus depends on gestational age Up to 85 85% % of infants affected if infected during first trimester. Prof. Muhammad Akram Hossain. Virology Review. 69.

(70) Papovavirus ds circular DNA, nonenveloped Two genus – Papillomavirus Human papilloma virus Skin warts, genital warts, laryngial papiloma – Polyomavirus BK, JC virusvirus- Progressive multifocal leucoencephalopathy. Prof. Muhammad Akram Hossain. Virology Review. 70.

(71) Poxviruses Smallpox virus virus-- Variola virus, last case detected in Bangladesh in 1975 and in the world in 1977(somalia), 1977 (somalia), officially eliminated in 1979 Vaccinia virus Molluscum contagiosum virus. Prof. Muhammad Akram Hossain. Virology Review. 71.

(72) Parvovirus Ss DNA virus Human parvo virus B19 – common manifestation is Erythema infectiosum – ( fifth disease), Transient aplastic crisis, Hydrops fetalis. Prof. Muhammad Akram Hossain. Virology Review. 72.

(73) Adenoviruses DNA, DS Non--enveloped (Naked) Non. Causes – Respiratory tract disease – Ocular diseases – Gastrointestinal diseases. Prof. Muhammad Akram Hossain. Virology Review. 73.

(74) What are Neurotropic viruses? Rabies virus Poliovirus Herpis simplex virus type 1 Herpis simplex virus type 2 Varicella zoster virus Arbovirus causing encephalitis. Prof. Muhammad Akram Hossain. Virology Review. 74.

(75) Arboviruses Arthropod borne viruses Important members are: 1. 2. 3. 4. 5. 6. 7. 8.. Dengue virus Yellow fever virus Japanese B encephalitis virus West Nile fever Tick borne encephalitis Eastern equine encephalitis Western equine encephalitis Ebola virus.

(76) Robovirus New group of virus recently emerged The viruses are rodent borne 1. Sin Nombre virus 2. Whitewater Arroyo – Causes haemorragic fever /ARDS. Prof. Muhammad Akram Hossain. Virology Review. 76.

(77) Nipah virus Paramyxovirus, named according to pace of Malyasia, where first discovered – Ss RNA – Enveloped – Still endemic in Bangladesh. Reservoir( fruit bat, pig ) Causes Encephalitis. Prof. Muhammad Akram Hossain. Virology Review. 77.

(78) Human oncogenic viruses virus. Human cancer. Human papilloma virus. Genital tumor squamas cell ca. EB virus HHV 8 HBV. Nasopharyngial ca Burkits lymphoma, Kaposis sarcoma Hepatocellular carcinoma. HTL virus. Adult T cell leukemia. HCV. Hepatocellular carcinoma Prof. Muhammad Akram Hossain Virology Review. 78.

(79) Mechanism of oncogenesis RNA tumor viruses revealed the involvement of cellular oncogene in neoplasia DNA tumor viruses established a role for cellular tumor suppressor gene. Prof. Muhammad Akram Hossain. Virology Review. 79.

(80) Dengue virus C. M. E (dimer). Flavivirus – ssRNA, + polarity. 4 serotypes RNA CpM E. NS1 2a2b 3. Prof. Muhammad Akram Hossain Virology Review. 4a 4b. 5. 80.

(81) Discuss the pathogenesis of dengue haemorrhagic fever fever.. List the complications of measles and rubella. Prof. Muhammad Akram Hossain. Virology Review. 81.

(82) Pathogenesis: Dengue Hemorrhagic Fever (DHF) – Four different serotypes of Dengue virus – Initial infection: infection: Neutralizing Ab vs. vs. intial strain – ReRe-infection due to different serotype: serotype: NonNonneutralizing Ab Immune complexes Enhanced uptake by monocytes Infection/lysis of monocytesmonocytes-release of cytokines ( IL 2, TNF α, IFNÿ IFNÿ ,LT, anticoagulants, procoagulants. Prof. Muhammad Akram Hossain. Virology Review. 82.

(83) What are the clinical feature and complications of Measles virus? Clinical features includeHectic fever, URTI, mucosal Koplik spots, Skin rash – from face, down the trunk and along limbs. Herpetic gingivostomatitis Otitis media - secondary bacterial Conjunctivitis – self limiting Corneal ulceration- following vitamin A deficiency due to PEM Complications. Pneumonia – both primary (Giant cell pneumonia) and secondary bacterial pneumonia. Croup – laryngotracheobronchitis Encephalitis - 0.1% Subacute sclerosing panencephatilitis (SSPE)- very rare, 1 in 100,000. Occurs 5 – 12 years after infection. Due to autoimmune demyelination. Prof. Muhammad Akram Hossain. Virology Review. 83.

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(85) How measles can be prevented? Why vaccine is administered after 9 months in Bangladesh?. Active immunization Measles is prevented by live attenuated vaccine. When administered in 2nd year gives 95% protection practiced in developed countries. In Bangladesh and other developing countries vaccine from Schwarz strain is given in 9 months with 85% protection. If given earlier antibody from mother interferes with vaccine activity.. Passive immunization Human Immunoglobulin within 5 days of exposure. Prof. Muhammad Akram Hossain. Virology Review. 85.

(86) Ques: Name 5 important infecting respiratory tract? Ans:. viruses. Influenza Parainfluenza Respiratory syncitial (RSV) Adeno viruses Rhino viruses Cornona virus Picorna viruses. Prof. Muhammad Akram Hossain. Virology Review. 86.

(87) What is street and fixed rabies virus? How can you prevent rabies? Street virus when freshly isolated in the laboratory where incubation period is variable Fixed virus Serial brain to brain passage in rabbits where incubation period is fixed.. Prevention of rabies Pre-exposure prophylaxis By active immunization Post-exposure prophylaxis By immunoglobulins Types of vaccine (active immunization) Human diploid cell vaccine (HDCV) *Rabies vaccine adsorbed (RVA) *Purified chick embryo cell vaccine(PCEV) *Nerve tissue vaccine Duck embryo vaccine. Types of rabies antibody: (passive immunization) Rabies immune globulin human(RIGH) Antirabies serum equine Prof. Muhammad Akram Hossain. Virology Review. 87.

(88) Check list (Virology •Basic knowledge about virus structure, classification, replication, difference from bacteria, Prions, viroids. •Name common viral diseases with their causative agents. •Details about HAV HBV,HCV,HDV, HIV, Rotavirus, Poliovirus, Herpes simplex, other Herpes viruses, •In short about Rabies, Measles, Mumps, Dengue, Influenza, parainfluenza, RSV, Rhino, Adeno, corona, picorna, Arboviruses.. Prof. Muhammad Akram Hossain. Virology Review. 88.

(89) Wish You All the best Prof. Muhammad Akram Hossain. Virology Review. 89.

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