MV

• Human Adenovirus


  • Naked viruses with an icosahedral nucleocapsid composed of hexons, pentons & fibers
  • Have toxic activity associated with pentons & hemagglutinating activity associated with pentons & fibers
  • Contain double-stranded DNA
  • Replicate in the nucleus of epithelial cells
  • Cause localized infections of the eye, respiratory tract, GIT & urinary bladder
  • Frequently cause subclinical infections
• Adenovirus Classification


  • Group B Adenovirus
  • Group C Adenovirus
  • Group D Adenovirus
  • Group E Adenovirus
  • Group F & G Adenovirus
• Group B Adenovirus


  • Cause acute respiratory disease, pharyngoconjunctival fever & hemorrhagic cystitis
  • Can cause epidemics in military recruits (Adenovirus type 7)
• Group C Adenovirus


  • Cause about 50% of acute respiratory diseases in young children
  • Cause latent infections in the tonsils, adenoids & other lymphatic tissue
• Group D Adenovirus


  • Are associated with sporadic & epidemic keratoconjunctivitis
  • Cause pink eye (Adenovirus type 8)
• Group E Adenovirus


  Are associated with acute respiratory disease accompanied by fever 7 with epidemic keratoconjunctivitis in military recruits
• Group F & G Adenovirus

  Cause gastroenteritis
• Diagnosis of Adenovirus infections

  • Observe rise in neutralizing antibody titer
  • Virus isolation from the eyes, throat or urine
  • ELISA procedures on fecal specimens from patients with gastrointestinal infections
• Herpes Viruses


  • Diverse group of large DNA viruses that share a common virion morphology, basic mode of replication, the capacity to establish latent/recurrent infections and the importance of cell-mediated immunity for controlling infection and causing symptoms
  • Enveloped viruses with an icosahedral nucleocapsid containing double-stranded DNA
  • Have a tegument or fibrous material between the nucleocapsid and envelope
  • Replicate in the nucleus of the host cell
  • Have an oncogenic potential
  • Can cause latent infections as well as acute infections
• HSV types 1 & 2

  • Produce both common antigens & type-specific antigens
  • Produce a virus-specific DNA polymerase & thymidine kinase which are necessary for replication
  • Are frequently latent in neurons
  • Can produce disitinctive cytopathology (cell rounding polykaryocyte formation) or inclusion bodies (Cowdry type A inclusion) in infected cells
• HSV-1 disease


  • May involve a primary infection (gingivostomatitis) or recurrent infection (cold sore)
  • Usually clinically inapparent as a primary disease
  • Usually present as lip, skin or eye lesion
  • Can progress to a severe, fatal encephalitis
• HSV-2 disease


  • May involve a primary or recurrent infection
  • Affects the genital or lip area
  • Most frequently transmitted sexually
  • Includes neonatal herpes, a severe generalized disease of the newborn, caused by virus infection during passage through an infected birth canal
  • May include cervical or vulvar carcinoma
• Varicella-Zoster Virus (VZV)


  Latent in neurons
• Varicella (Chicken pox)


  • Mild highly infectious, generalized disease usually observed in children
  • Characterized clinically by vesicles on the skin & mucous membranes
  • May be diagnosed by Tzanck smear or fluorescent antibody staining of viral antigens in scrapings; virus isolation also possible
• Zoster (shingles)


  • Reactivated virus infection in adults
  • Characterized by severe pain and the presence of vesicles in a specific area of the skin or mucosa supplied with nerves from one ganglia
• Cytomegalovirus (CMV)


  • Replicates more slowly; replicates only in human fibroblasts
  • Causes an acute primary infection & a latent infection that is replicated to clinical disease only during immunosuppression
• Clinical manifestation of CMV

  • Inapparent disease in children & adults but can cause an infectious mononucleosis-like disease
  • Retinitis & pulmonary disease may occur in immunosuppressed individuals
  • Cytomegalic inclusion disease - Generalized infection of infants with a distinct clinical syndrome that includes jaundice with hepatosplenomegaly, thrombocytopenia purpura, pneumonia & CNS damage
• Epstein-Barr Virus (EBV)


  • Infects & transforms human B lymphocytes
  • Produce several distinct antigens: nuclear antigens (EBNA), latent membrane proteins (LMP), a viral capsid antigen (VCA) & two small RNAs (EBERS)
• Infectious mononucleosis


  • Disease of children & young adults (sometimes called Kissing's disease)
  • Characterized by fever & enlarged lymph nodes & spleen
  • Associated with the production of atypical lymphocytes & IgM heterophile antibodies identified by mononucleosis spot test
  • Can also be diagnosed by serologic tests involving indirect immunofluorescence procedures on fixed EBV producing cells or ELISA tests
• Burkitt's lymphoma & Nasopharyngeal carcinoma


  • Patients with these diseases have increased antibody titers to EBV
  • They also have cells that express EBNA & carry multiple copies of viral DNA
• Parvoviruses


  • Very small viruses with naked icosahedral nucleocapsids, containing single- stranded DNA & replicates in the nucleus
  • Diagnosis done by detection of virus-specific IgM
• Human Parvovirus


  • Enters the body through the respiratory tract & infects & lyses progenitor erythroid cells
  • Causes febrile illness in blood recipients, aplastic crises in patients with hemolytic anemias & erythema infectiosum (fifth disease) in normal healthy individuals
• Papovavirus


  • Naked viruses with an icosahedral nucleocapsid that contains double-stranded circular DNA
  • Replicate in the nucleus of the cell
  • Produce latent & chronic infection in their natural host
• Human Papilloma virus


  • Replicates in the epithelial cell of the skin
  • Forms keilocytotic (vacuolated) cells during replication
  • Is directly transferred from person to person
  • Causes warts & laryngeal papillomas
  • Have been associated with cervical tumors & vulvar & penile cancers
• Human Polyomavirus


  • JC virus-isolated from patients with multifocal leukoencephalopathy
  • BK virus - latently infects the kidney but can cause urinary tract infections in immunosuppressed persons
  • Infection can be detected by the presence of koilocytotic squamous epithelial cells
• Pox virus


  • Have a complex brick-shaped virion that consists of an outer envelope enclosing a core containing linear double-stranded DNA & two lateral bodies
  • Produce eosinophilic inclusion bodies called Guarnieri bodies & membrane hemagglutinins in infected cells
• Variola virus


  Causes smallpox, a generalized viral infection that presumably has been eradicated by WHO vaccination program
• Vaccinia virus


  Is the variant of variola virus that generally produces only a mild disease & is used as the immunogen in smallpox vaccination
• Molluscum contagiosum


  • Infects epithelial cells, where it causes a localized disease that usually resolves spontaneously in several months but may persists for 1-2 years
  • Causes small, wart-like lesions on the face, arms, back, buttocks and genitals
  • Transmitted by direct or indirect contact
  • Can cause a sexually transmitted disease with popular lesions that can ulcerate & mimic genital herpes
  • Forms characteristic eosinophilic inclusion bodies in infected cells
• Diagnosis of smallpox is through inoculation into an embryonated egg; Molluscum contagiosum is confirmed histologically by the presence of very characteristic eosinophilic cytoplasmic inclusions (molluscum bodies) in epithelial cells
• Hepatitis B virus