Virology Notes PDF

26/09/2024 VIROLOGY PREPARED BY: LAODICEA A. SY, RMT VIROLOGY Virus – obligate intracellular parasites unable to self-replicate * either DNA or RNA; do not have a system to produce ATP. Viral Structure: 1. Virion – entire viral particle. 2. Capsid – protein coat that encloses the genetic material....

26/09/2024 VIROLOGY PREPARED BY: LAODICEA A. SY, RMT VIROLOGY Virus – obligate intracellular parasites unable to self-replicate * either DNA or RNA; do not have a system to produce ATP. Viral Structure: 1. Virion – entire viral particle. 2. Capsid – protein coat that encloses the genetic material. 3. Capsomer – protein subunit that makes up the capsid 1  26/09/2024 VIROLOGY 4. Nucleocapsid – composed of the capsid and genetic material. 5. The envelope – outer coating composed of a phospholipid bilayer (viral- encoded glycoproteins) and sometimes viral encoded matrix proteins. 2  26/09/2024 Replication 1. Adsorption – attachment of the virus to a specific receptor on the host cell. 2. Pentration – entry of the virus into the host cell. 3. Uncoating occurs when there is either the separation of the capsid from the genome or rearrangement of the capsid proteins exposing the genome for transcription and replication. 4. The eclipse period – stage when the genetic material is replicated but intact virions are not yet detectable. a. Viral DNA or RNA serves as the template for mRNA production. b. mRNA codes for viral protein and enzymes necessary for nucleic acid synthesis. 5. Assembly (maturation): Genetic material is assembled into a protein coat. 6. Viruses are then released from the host cell: A. Cell lysis: Naked viruses lyse host cell (leave through a hole in the plasma membrane). B. Budding: Intact virion pushes outward from a host's membrane; membrane wraps around the virion; membrane cleaved & resealed around the virion, becoming the viral envelope. 3  26/09/2024 VIROLOGY Rule: DNA viruses 1. All are DS DNA except Parvovirus 2. All are icosahedral except Poxvirus 3. All are enveloped except PAP (Papovavirus, Adenovirus, Parvovirus) 4. All multiply in nucleus except Poxvirus 4  26/09/2024 VIROLOGY Rule: RNA viruses 1. All are SS RNA except Reovirus 2. All are enveloped except PCR – Picornavirus, Calicivirus, Reovirus 3. All are non segmented except ROBA – Reovirus, Orthomyxovirus, Bunyavirus, Arenavirus 4. Generally helical except the positive sense RNA viruses VIROLOGY 4. Generally helical except the positive sense RNA viruses 5. Positive Sense – Calicivirus, Picornavirus, Flavivirus, Togavirus, Coronavirus, Retrovirus (ICOSAHEDRAL) 6. Negative Sense – Paramyxovirus, Orthomyxovirus, Rhabdovirus, Bunyavirus, Arenavirus (HELICAL) 5  26/09/2024 HumanDNA Viruses FAMILY NAME REPRESENTATIVE VIRUSES INFECTION(S) Adenoviruses Adenoviruses,>60 serotypes divided Typically mild respiratory, urinary tract, GI, & into subgroups eye infections; highly contagious pink eye (conjunctivitis) Hepadnaviruses HBV Hepatitis B Herpes viruses Herpes simplex viruses(HSV 1, HSV Oral, genital, neonatal, & ocular herpes, HSV 2) encephalitis Varicella zoster virus (VZV) Chicken pox (varicella),shingles(zoster) Epstein Barr virus (EBV) Infectious mononucleosis Cytomegalovirus(CMV) Infections in newborns & immunocompromised Human herpesviruses 6–8 Roseola, Kaposi sarcoma Papillomaviruses Human papilloma virus (HPV) Warts, including genitalwarts that are linked to cervical cancer Parvoviruses Parvovirus B19 Fifth disease (erythema infectiosum) Poxviruses Variola Small pox Human RNA Viruses COMMON FAMILY NAME REPRESENTATIVE VIRUSES INFECTION(S) Arenaviruses Lymphocyte choriomeningitis Aseptic meningitis or virus (LCM) meningoencephalitis Lassa fever Lassa fever virus Astroviruses Astrovirus Gastroenteritisin children, elderly, and immunocompromised Hantaviridae Hantavirus (Sin Nombre virus) Hantavirus pulmonary syndrome (HPS) Caliciviruses Noroviruses infectious gastroenteritisi Coronaviruses Coronavirus Severe acute respiratory syndrome (SARS), cold like infections, pediatric diarrhea, COVID 19 6  26/09/2024 Human RNA Viruses COMMON FAMILY NAME REPRESENTATIVE VIRUSES INFECTION(S) Filoviruses Marburg & Ebola viruses Hemorrhagic fever Flaviviruses Yellow fever virus, Japanese Yellow fever, Japanese encephalitis, encephalitis virus, dengue virus, dengue fever, West Nile virus West Nile virus, Zika virus infection, Zika Note: above viruses are arboviruses (arthropod borne viruses) Hepatitis C virus (HCV) Hepatitis C Orthomyxoviruses Influenza A, B, & C Influenza Human RNA Viruses COMMON FAMILY NAME REPRESENTATIVE VIRUSES INFECTION(S) Paramyxoviruses Measles virus Measles(rubeola) Mumps virus Mumps Parainfluenza virus RTI in children Respiratory syncytial virus (RSV) RTI in infants, elderly, immunocompromised Human metapneumovirus(HMPV) RTI Picornaviruses Enteroviruses(polioviruses, Polio, hand foot mouth disease, coxsackieviruses A & B, echoviruses, aseptic meningitis, others enteroviruses) Hepatitis A virus (HAV) Hepatitis A Rhinovirus Common cold Reoviruses Rotavirus Gastroenteritis in infants & children 7  26/09/2024 Human RNA Viruses COMMON FAMILY NAME REPRESENTATIVE VIRUSES INFECTION(S) Retroviruses IV 1, HIV 2 AIDS Human T lymphotropic T cell leukemia & lymphoma, viruses(HTLV1, HTLV 2) tropicalspastic paraparesis Rhabdoviruses Rabies virus Rabies Togaviruses Rubella virus Rubella (German measles) Eastern,Western, & Venezuelan Eastern,Western, & Venezuelan equine encephalitis viruses encephalitis Hepatotrophic viruses: 1. HAV ( Picornavirus) – Infectious hepatitis 2. HBV ( Hepadnavirus) – Serum hepatitis 3. HCV ( Flavivirus) – Post transfusion, NANB 4. HDV (Viroid like) – require HBV infection 5. HEV ( Calicivirus/Hepevirus) – Water borne 6. HGV ( Flavivirus) – Blood borne hepatitis 8  26/09/2024 Hepatotrophic Viruses Specimen Collection and Transport 9  26/09/2024 Laboratory Transport medium:  Stuart’s medium; Leibovitz-Emory medium  Earles/Hanks BSS, amino acids, vitamins and bicarbonates, Penicillin-Streptomycin, phenol red Methods to Identify: 1. Electron microscope– viral morphology; 2. Light Microscopy (phase contrast) – inclusion bodies 3. Viral Ag - immunofluorescence 4. Serology – ELISA, IFT, Latex STUART MEDIUM 10  26/09/2024 Electron Microscope SEM TEM 5. Viral genome- PCR, SBHT, NBHT 6. Virus isolation/culture  Cell culture- CPE (Cytopathic effect), hemadsorption  Eggs- pock formation on CAM; Animals- death of animal 11  26/09/2024 Types of Cell Culture: 1. Primary cell- passed only once; PMKC 2. Semi continuous – passed 50x (HDF) 3. Continuous-malignant, passed indefinitely (MD CK, HEP-2C, L20B, RD- A, Hela) Characteristic CPE:  Rounding necrosis – Enterovirus  Ballooning/Giant cell – HSV; Grape like cluster – Adenovirus  Syncytium form – RSV/Measles/Rubella; Hemadsorption – Influenza, Parainfluenza, Measles and Mumps  Refractile, round cell – Rhinovirus (33’C);  No CPE – Parainfluenza, mumps, Influenza 12