FPV is in the family Parvoviridae, which contains 26 species of virus that infect a broad host range, covering species from invertebrates to humans. Parvoviruses are small single stranded DNA viruses enveloped by a T=1 non-enveloped capsid protein. Replication of these viruses can only occur when the host cell is in S-phase of its mitotic cycle (15). FPV has a very small linear genome that is only 5 kilobases in length (4). The virus’s genome has specific sequences, similar to a TATA boxes, that initiate transcription of major virus specific mRNA. A combination of TGTAAAT at nucleotide 893 and TAAAATA at nucleotide 878 begin the transcription. mRNA transcription is terminated at nucleotide 3816 with the sequence AATAAA, which is characteristic
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These structural sequences are found in the rightward open reading frame of the genome. The virus’s unique capsid structure allows it to effectively bind to and infect feline cells. The capsid of FPV is made up of a large protein (VP1 at 80,000 Daltons) and a smaller protein (VP2 at 60,000 Daltons)(4). While there is a specific genetic sequence that codes from the VP1 protein, VP2 is modified from a precursor protein called VP2’, which is about 4,000 Daltons larger than VP2. Additionally, the sequence for VP2’ is contained within the sequence coding for VP1 and requires exon splicing (3,4). Once VP2’ has been synthesized, 30 amino acids are removed from its amino terminus through proteolytic cleavage (4). The end result is a nested set of VP1 and VP2 creating FPV’s unique capsid. VP2 makes up 90% of the capsid structure (9). The core structure of both VP1 and VP2 consists of an eight-stranded, anti-parallel β-barrel arrangement in which large loops link together β-strands. These strands make up a majority of the capsid and create protruding loop structures that inhibit antibodies from binding and define the virus’s host range by binding to host specific transferrin receptor proteins …show more content…
Specifics of this process in FPV continue to be studied, but there is evidence outlining a replication mechanism. Certain proteins are autonomously replicated, but FPV relies on the host cell’s central dogma machinery for most of its metabolism and structural protein synthesis (22). In their study, Lenghaus, Mun, and Studdert found that replication of the virus can still proceed even when cellular processes have been halted (15). These results suggest that FPV does not require the host cell’s full central dogma machinery to carry out its replication. An important sequence of FPV is a hairpin structure found at the 3’ end of viral DNA. This sequence serves as a primer template for the host cell’s DNA polymerase (4,20). As previously discussed, FPV’s genome contains sequences resembling the TATA box and polyadenylation sites that initiate and terminate transcription by host polymerase. Host cells may also contain an hnRNP A/B protein that reduces the affinity of DNA polymerase to bind to viral DNA, thus reducing its ability to replicate (22). However, not all host cells contain this protein at high enough concentrations to block FPV
These structural sequences are found in the rightward open reading frame of the genome. The virus’s unique capsid structure allows it to effectively bind to and infect feline cells. The capsid of FPV is made up of a large protein (VP1 at 80,000 Daltons) and a smaller protein (VP2 at 60,000 Daltons)(4). While there is a specific genetic sequence that codes from the VP1 protein, VP2 is modified from a precursor protein called VP2’, which is about 4,000 Daltons larger than VP2. Additionally, the sequence for VP2’ is contained within the sequence coding for VP1 and requires exon splicing (3,4). Once VP2’ has been synthesized, 30 amino acids are removed from its amino terminus through proteolytic cleavage (4). The end result is a nested set of VP1 and VP2 creating FPV’s unique capsid. VP2 makes up 90% of the capsid structure (9). The core structure of both VP1 and VP2 consists of an eight-stranded, anti-parallel β-barrel arrangement in which large loops link together β-strands. These strands make up a majority of the capsid and create protruding loop structures that inhibit antibodies from binding and define the virus’s host range by binding to host specific transferrin receptor proteins …show more content…
Specifics of this process in FPV continue to be studied, but there is evidence outlining a replication mechanism. Certain proteins are autonomously replicated, but FPV relies on the host cell’s central dogma machinery for most of its metabolism and structural protein synthesis (22). In their study, Lenghaus, Mun, and Studdert found that replication of the virus can still proceed even when cellular processes have been halted (15). These results suggest that FPV does not require the host cell’s full central dogma machinery to carry out its replication. An important sequence of FPV is a hairpin structure found at the 3’ end of viral DNA. This sequence serves as a primer template for the host cell’s DNA polymerase (4,20). As previously discussed, FPV’s genome contains sequences resembling the TATA box and polyadenylation sites that initiate and terminate transcription by host polymerase. Host cells may also contain an hnRNP A/B protein that reduces the affinity of DNA polymerase to bind to viral DNA, thus reducing its ability to replicate (22). However, not all host cells contain this protein at high enough concentrations to block FPV