CLASS I: Double-stranded DNA
- OPV are enveloped brick-shaped viruses (350 × 270 nm) containing a double-stranded DNA genome with a size of approximately 200 kb, the ends of which are connected by covalent links
- the different OPV species cannot be distinguished by means of electron microscopy
- OPV are closely related to each other with regard to antigens and show marked homology at the genome level
- The genome of the poxviruses encodes for 150–200 different genes
- Unlike other DNA viruses, poxviruses replicate in the cytoplasm of infected cells in so-called virus factories (Guarnieri inclusion bodies)
- Originally, four different infectious virus particles were ...view middle of the document...
* The incubation period of the infection ranges from four to 14 days but can last as long as 21 days
* clinical conditions associated with the infection include erythema infectiosum; arthropathy; transient aplastic crisis; chronic red cell aplasia; papular, purpuric eruptions on the hands and feet (“gloves and socks” syndrome); and hydrops fetalis
QUESTION 2: The following are possible modes of transmission of human harpovirus EXCEPT:
a. blood transfusion
b. bone marrow transplant
c. from mother to baby via the placenta.
d. intramuscular immunoglobulins
Transmission is usually via respiratory secretions, but it can also be passed on via blood transfusion, bone marrow transplant, other blood products (but not intramuscular immunoglobulins), and from mother to baby via the placenta.
CLASS III: Double-stranded RNA
- Mature virus particles are non-enveloped and possess a multilayered icosahedral protein capsid, of about 75nm in diameter, composed of an outer layer, an inner layer, and a core
- The virus genome consists of 11 segments of double-stranded RNA;
- Viral particles contain an RNA-dependent RNA polymerase and other enzymes capable of producing capped RNA transcripts
- Viral replication occurs in the cytoplasm of infected cells.
- The viruses are capable...