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IV Sequence Quality Filter System


IV Q-Filter: An IV nucleotide sequence quality filter system.
Aim: Since most of IV sequences in public resources are from direct submission, there is a growing need to curate and corroborate the data in order to analyze them effectively. To ensure data quality, the Q-Filter System is developed to classify nucleotide sequences into 7 categories according to certain criteria. It is useful to filter short sequences since the length of nucleotide sequences ranges from dozens to thousands of base pairs. This allows researchers to have a clear understanding on the sequence data and to choose high-quality data for their research.
Class Criteria:

The classification is based on sequence content (CDS, 5'UTR, 3'UTR) and integrity (C: complete or P: partial). The 7 categories are C1-C4 and P1-P3, respectively. The C1-C4 sequences have complete CDS and differ in UTRs (such as without UTR, with 5'/3' UTR or both). The P1-P3 sequences have partial CDS and differ in without UTR or with 5'/3'UTR.
C1: Complete CDS                        
C2: 5'UTR+complete CDS              
C3: 3'UTR+complete CDS              
C4: 5'UTR+complete CDS+3'UTR   
P1: Partial CDS                             
P2: 5'UTR+partial CDS                  
P3: 3'UTR+partial CDS                  

For example, if the length of a nucleotide sequence is 1,136 bp with CDS length 1,125 bp and CDS range 4-1,128 bp, the nucleotide sequence belongs to category C4: 5'UTR+complete CDS+3'UTR. For segment which has more than one CDS, such as PB1, M and NS, taken nucleotide sequence AJ419128 for example, it belongs to C3:3'UTR+complete for one CDS and P2:5'UTR+partial for the other CDS, so this nucleotide sequence belongs to category C3,P2.

UTR download:

This section offer UTR search and download and the search options are the same as the Main Search.


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