Term
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Definition
| element of na that replicates inside living cells using the cellular synthetic machinery for production of progeny virions |
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Term
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Definition
| Range of animal species and tissue cells that the virus can infect. May be broad or limited... most only infect specific cell types in one host species. |
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Definition
| Protein structural unit which may be assembled to form a capsomere. (sand) |
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Definition
| Made up of protomers. It is the subunit from which the capsid is built. (brick) |
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Definition
| It is the protein shell enclosing the nucleic acid genome. All viruses have this. |
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Definition
| Host cell-derived, lipid-containing membrane which surrounds some viruses. |
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Definition
| Capsid + enclosed nucleic acid |
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Definition
| Complete infective virus particle |
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Definition
| Empty capsid. Virion without nucleic acid. Incomplete helical virions DO NOT exist. The number of these helps determine virulence (high # = low virulence) |
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Definition
| A virus which lacks a full complement of viral genes, and can only replicate in mixed infections with a helper virus. |
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Definition
| The genome of one virus may become encapsidated in a heterologous protein coat encoded by a different virus. This occurs during replication and is unintentional. |
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Term
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Definition
| Capsid encloses host nucleic acid. Particles look like virus particles, but do not replicate. Occurs when viruses are replicating in the nucleus. |
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Definition
| Autonomous extrachromosomal genetic element. May later become integrated into chromosomal DNA, may stay separate. |
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Definition
Viral DNA which is integrated into host cell chromosome in a latent state and must be activated before it is transcribed to produce progeny virions.
Transmissible from parent cell to daughter cells. |
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Definition
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Definition
| Contains an outer, middle, and inner capsid |
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Definition
| Made of capsomeres held together by NONCOVALENT bonds. |
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Definition
Icosahedron
12 corners+20 triangular faces+30 edges |
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Definition
Cubic symmetry
12 corners+20 triangular faces+30 edges |
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Definition
| Capsomeres located at the vertices of icosahedral virions. Each is surrounded by 5 neighbor capsomeres. Found on Adenoviruses |
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Term
| T/F: Only RNA viral groups contain viruses with cubic symmetry. |
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Definition
| F. Both DNA and RNA viral groups contain viruses with cubic symmetry |
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Term
| T/F: Viruses can reproduce by binary fission. |
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Definition
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Term
| T/F: Viruses posses both DNA and RNA. |
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Definition
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Term
| T/F: Viruses are not sensitive to antibiotics. |
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Definition
| T. However, since they can reproduce inside bacteria, the use of antibiotics in a viral infection may be useful in controlling the infection. |
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Term
| T/F: Viruses, but not bacteria, are sensitive to interferon. |
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Definition
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Term
| T/F: Viruses have a diameter of greater than 300 nm. |
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Definition
| F: Bacteria are larger than 300 nm in diameter, but viruses are not. |
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Term
| T/F: Viruses have functional ribosomes. |
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Definition
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Term
| T/F: Viruses have a plasma membrane. |
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Definition
| F. Viruses do not have a plasma membrane. Enveloped viruses may, however, incorporate host cell membranes into their envelope. |
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Term
| T/F: Viruses and some bacteria are obligate intracellular parasites. |
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Definition
| T. Rickettsia chlamydophila (bact) and viruses are obligate intracellular parasites. |
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Term
| T/F: Viruses lack ATP generating metabolism. |
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Definition
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Term
| T/F: Viruses cannot survive outside the body because they are obligate intracellular parasites. |
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Definition
| F. They are considered obligate intracellular parasites, but they can survive outside their hosts. They are considered obligate because they cannot reproduce outside of host cells. |
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Term
| T/F: Helical symmetry of some viruses is caused by the interaction between capsid proteins and nucleic acid, forming a structure which is self-assembling. |
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Definition
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Term
| T/F. In all animal viruses, helical nucleocapsids are wound into a coil and enclosed within a lipoprotein envelope. |
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Definition
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Term
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Definition
Virus particles not exhibiting simple cubic or helical symmetry.
e.g. poxviruses |
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Term
| T/F: The attachment site of all viruses is at the "spikes". |
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Definition
| F. Spikes are the attachment site for enveloped viruses only. For naked viruses, parts of the capsid itself are the attachment sites. |
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Term
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Definition
| Spike. It is involved in receptor binding. |
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Term
| T/F: The polysaccharides of the glycoprotein peplomeres are derived from the viral genome. |
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Definition
| F. They are host cell derived. |
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Term
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Definition
| Fusion proteins are associated with peplomeres and involved in key steps in viral entry into and viral release from cells. It joins the envelope to the cell membrane. Acts as "finger print", allowing Abs to direct NK killing of infected cell. |
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Term
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Definition
| Layer inside some envelopes. Serves as a recognition site for the nucleocapsid at the plasma membrane and provides added rigidity. |
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Term
| T/F: Most enteritis is caused by enveloped viruses. |
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Definition
| F. Because enveloped viruses are more susceptible to attachment site disruption from bile fluids, most cases of enteritis are caused by naked viruses. |
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Term
| T/F: Unlike other membranes, viral envelopes are not selectively permeable and block the entry of all chemicals and enzymes into the virus particle. |
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Definition
| F. They are selectively permeable like all membranes, and MAY block chemicals or enzymes. |
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Term
| Viral proteins make up what percentage of the virion? |
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Definition
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Term
| T/F: Viral proteins include structural proteins, regulatory proteins and enzymes. |
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Definition
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Term
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Definition
| These are encoded in the genome of the virus, and they copy part or all of the viral genome, sometimes immediately on entry into the host cell. |
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Term
| Enzymes transcribing viral genomes into mRNAs. |
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Definition
| DNA-dependent RNA polymerase & RNA-dependent RNA polymerase. |
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Term
| T/F: DNA-dependent RNA polymerase containing viruses replicate in the nucleus and can thus produce pseudovirions. |
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Definition
| F. DNA-dependent RNA polymerase containing viruses only replicate in the cytoplasm and, therefore, cannot generate pseudovirions. |
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Term
| RNA-dependent RNA polymerase |
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Definition
| Carried by viruses with a (-) sense RNA genome. Host cells lack this enzyme. |
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Term
| T/F: Host cells lack the enzyme RNA-dependent RNA polymerase. |
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Definition
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Term
| DNA-dependent RNA polymerase |
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Definition
| Carried by DNA viruses which replicate in the cytoplasm. |
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Term
| Enzymes that copy virion RNA into DNA |
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Definition
| RNA-dependent DNA polymerase |
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Term
| RNA-dependent DNA polymerase synonym |
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Definition
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Term
| RNA-dependent DNA polymerase |
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Definition
| Carried by adnaviruses and retroviruses such as HIV |
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Term
| Enzymes that copy nucleic acid genome |
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Definition
DNA-dependent DNA polymerase
RNA-dependent RNA polymerase |
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Term
| RNA-dependent RNA polymerase synonym |
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Definition
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Term
| T/F: All viral genomes are haploid. |
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Definition
| F. All viruses except for retroviruses have haploid genome. Retrovirus genomes are diploid. |
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Term
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Definition
| All viral genes are contained in a single chromosome. |
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Term
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Definition
| Segmented. Viral genes distributed among several chromosomes which constitute the viral genome. |
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Term
| T/F: Viral genomes may be either DNA or RNA. |
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Definition
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Term
| T/F: DNA genomes may be either monopartite or multipartite. |
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Definition
| F. They are only monopartite. |
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Term
| T/F: DNA genomes can only be double stranded. |
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Definition
| F. DNA genomes may be either ds or ss. |
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Term
| T/F: RNA genome may only be single stranded. |
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Definition
| F. RNA genomes may be either ss or ds. |
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Term
| T/F: RNA viral genomes may be either monopartite or multipartite. |
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Definition
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Term
| T/F:Positive-sense DNA genome viruses are immediately infective when injected into the cell. |
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Definition
| F. There is no such thing as a positive-sense DNA genome virus. |
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Term
| Positive sense RNA genome |
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Definition
| Can fxn as mRNA in the infected cell. |
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Term
| _______ _________ extracted from a (+) sense RNA virus is infectious when injected into the host cell. |
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Definition
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Term
| The chemical attached to (+) sense RNA is attached at the ________ end of the RNA. |
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Definition
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Term
| Cannot fxn as mRNA, so it carries its own transcriptase enzymes. |
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Definition
| Negative-sense RNA genome |
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Term
| In reference to negative-sense RNA genomes injected naked RNA is (infectious/not infectious). |
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Definition
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Term
| Where are viral lipids found? |
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Definition
| Envelope of enveloped viruses. |
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Term
| T/F: The envelope is a typical lipid bilayer with host-cell encoded glycoprotein peplomeres and, in some cases, other viral proteins embedded in it. |
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Definition
| F.T/F: The envelope is a typical lipid bilayer with VIRUS-CODED glycoprotein peplomeres and, in some cases, other viral proteins embedded in it. |
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Term
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Definition
| Most occur as membrane-anchored spikes which extend outward from the envelope. |
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Term
| Why are enveloped viruses more susceptible to environmental factors than naked viruses? |
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Definition
| Because the spikes (glycoprotein peplomeres) are the attachment site for the virus and anything which disrupts the envelope arrangement will disrupt the attachment site. |
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Term
| Viral surface proteins are denatured within _______ minutes at _______ to ______ degrees centigrade. |
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Definition
a few minutes,
55-60 degrees |
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Term
| T/F: Temperature denaturation makes the virion incapable of normal cellular attachment and penetration, but not uncoating. |
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Definition
| F. Denaturation renders the virus incapable of all three. |
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Term
| Most viruses survive best at what pH? |
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Definition
| Physiological pH, but some tolerate a wide pH range. |
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Term
| Acidic conditions can lead to reversible or irreversible disassembly of the _________ __________. |
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Definition
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Term
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Definition
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Term
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Definition
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Term
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Definition
| denotes the viral genus (pl. genera) |
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Term
| Main criteria for classification of viruses |
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Definition
1. Type and character of viral genome
2. Strategy of viral replication
3. Morphology of the virion |
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Term
| Grouping of viruses into families is based on: |
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Definition
size
structure
symmetry
type of n.a. strands and polarity
replication strategy |
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Term
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Definition
| deals with interrelationships among member viruses in a family |
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Term
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Definition
| classification of genera and species within a family are based on criteria which include host species, pathogenesis, nucleic acid homology, and antigenic differences |
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Term
| What are the two single stranded DNA virus families? What is the difference? |
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Definition
| Circorviridae and Parvoviridae. Circo- has + polarity, while Parvo- has - polarity. |
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Term
| T/F: Parvoviridae consists of two subfamilies, all of which are very small viruses which replicate only in actively dividing cells. |
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Definition
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Term
| Where does replication and assembly of Parvoviridae occur? |
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Definition
| In the nuclei of actively dividing cells |
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Term
| Do Parvoviruses produce inclusion bodies? If so, what kind and where? |
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Definition
| Yes: acidophilic intranuclear |
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Term
| T/F: Parvoviruses tend to be fragile and require close contact for transmission. |
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Definition
| F. They are extremely stable and may remain viable for long periods. |
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Term
| T/F: Parvoviruses may cause pseudovirions to form. |
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Definition
| T. Viruses that replicate in the nucleus may cause pseudovirions to form. |
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Term
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Definition
| Small viruses causing chronic, latent, and transforming infections in their natural hosts |
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Term
| The viral genome of which family or families of may be episomal or integrated into host cell DNA? |
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Definition
| Papillomaviridae, Polyomaviridae |
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Term
| Papillomaviruses encode proteins that promote _______ _______. |
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Definition
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Term
| Papillomaviruses replicate where? |
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Definition
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Term
| Do Papillomaviruses produce inclusion bodies? If so, what kind and where? |
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Definition
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Term
| Are papillomaviruses stable in the environment? |
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Definition
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Term
| Papillomaviruses cause what? |
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Definition
| warts, some may cause cancer esp. in humans |
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Term
| Adenoviruses are _________-sized viruses that have __________ for its attachment sites. |
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Definition
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Term
| The penton base and fiber are _______ to cells. |
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Definition
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Term
| Do Adenoviruses produce inclusion bodies? If so, what kind and where? |
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Definition
| Yes, they produce basophilic intranuclear inclusion bodies |
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Term
| Adenoviruses replicate where? |
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Definition
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Term
| T/F: Adenoviruses cause latent infections which may be reactivated by immunosuppression. An infection by Adenoviruses is lifelong. |
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Definition
| F. The infection is not lifelong. |
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Term
| Asfarviridae are _______-sized virions containing many proteins and several enzymes. |
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Definition
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Term
| Virus replication of Asfarviridae occurs where? |
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Definition
Cytoplasm of host cells....
Also in some soft ticks |
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Term
| Do Asfarviruses produce inclusion bodies? If so, what kind and where? |
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Definition
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Term
| The family of Herpesviridae contains how many subfamilies? |
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Definition
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