In this task, you are given a paragraph (from a research paper) and your task is to classify each sentence of the paragraph (assume n sentence) into the following categories: Background, Purpose, Method, Finding/Contribution, or Other. Return the output in this format: 1 - category of sentence 1, 2 - category of sentence 2, ..., n - category of sentence n; where each number indicates the order of the sentence. The categories can be identified using the following questions:
Background: - Why is this problem important? - What relevant works have been done before? - What did the previous works miss? - What are the high-level research questions? - How might this help other researchers?
Purpose: - What specific things do the researchers want to do? - What specific knowledge do the researchers want to know? - What specific hypothesis do the researchers want to test?
Method: - How did the researchers do it or find it out? - What are the procedures and steps of this research?
Finding/Contribution: - What did the researchers find out? Did the proposed methods work? - Did things behave as the researchers expected?
Other: put every text fragment that does not fit into any of the categories above here. Put a sentence here if its not in English, is not part of the article, contains numbers and dates, is a caption of a figure or a table, is a formatting error, or you are not sure about it.

[Q]: Porcine aminopeptidase N (pAPN) is a cellular membrane protein and a functional receptor for porcine coronaviruses. Here, we describe the heterologous expression of pAPN without signal peptide in BL21(DE3)pLysS host cells. The Escherichia coli (E. coli) harboring the recombinant construct was efficiently induced to express the pAPN protein at a high level. The most optimal expression profile for pAPN expression was investigated. By inoculating a rabbit with the purified pAPN, a high tittered specific antibody was achieved. Biologically, the antibody reacted with either pAPN-expressing E. coli or native pAPN on the surface of swine testis cells. The pAPN and its specific antibody blocked transmissible gastroenteritis coronavirus infection in vitro. Furthermore, the localization of pAPN on the small intestine of swine was analyzed by immunohistochemistry.
[A]: 1 - background, 2 - purpose, 3 - method, 4 - finding, 5 - finding, 6 - finding, 7 - finding, 8 - finding, 9 - finding

[Q]: The severe acute respiratory syndrome (SARS) has been one of the most epidemic diseases threatening human health all over the world. Based on clinical studies, SARS-CoV (the SARS-associated coronavirus), a novel coronavirus, is reported as the pathogen responsible for the disease. To date, no eective and specic therapeutic method can be used to treat patients suering from SARS-CoV infection. RNA interference (RNAi) is a process by which the introduced small interfering RNA (siRNA) could cause the degradation of mRNA with identical sequence specicity. The RNAi methodology has been used as a tool to silence genes in cultured cells and in animals. Recently, this technique was employed in anti-virus infections in human immunodeciency virus and hepatitis C/B virus. In this study, RNAi technology has been applied to explore the possibility for prevention of SARS-CoV infection. We constructed specic siRNAs targeting the S gene in SARS-CoV. We demonstrated that the siRNAs could eectively and specically inhibit gene expression of Spike protein in SARS-CoV-infected cells. Our study provided evidence that RNAi could be a tool for inhibition of SARS-CoV. 2004 Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.
[A]: 1 - background, 2 - background, 3 - background, 4 - background, 5 - background, 6 - background, 7 - background, 8 - purpose, 9 - method, 10 - finding, 11 - finding, 12 - other

[Q]: Background: Despite current knowledge of mutations in 45 genes that can cause nonsyndromic sensorineural hearing loss (SNHL), no unified clinical test has been developed that can comprehensively detect mutations in multiple genes. We therefore designed Affymetrix resequencing microarrays capable of resequencing 13 genes mutated in SNHL (GJB2, GJB6, CDH23, KCNE1, KCNQ1, MYO7A, OTOF, PDS, MYO6, SLC26A5, TMIE, TMPRSS3, USH1C). We present results from hearing loss arrays developed in two different research facilities and highlight some of the approaches we adopted to enhance the applicability of resequencing arrays in a clinical setting. Results: We leveraged sequence and intensity pattern features responsible for diminished coverage and accuracy and developed a novel algorithm, sPROFILER, which resolved >80% of no-calls from GSEQ and allowed 99.6% (range: 99.2-99.8%) of sequence to be called, while maintaining overall accuracy at >99.8% based upon dideoxy sequencing comparison. Conclusions: Together, these findings provide insight into critical issues for disease-centered resequencing protocols suitable for clinical application and support the use of array-based resequencing technology as a valuable molecular diagnostic tool for pediatric SNHL and other genetic diseases with substantial genetic heterogeneity.
[A]:
1 - background, 2 - background, 3 - method, 4 - method, 5 - finding, 6 - finding, 7 - finding, 8 - finding