Definition: In this task, you're given a paragraph from the research paper and your task is to generate a suitable title for the research paper based on the given paper. Under 100 words is a good title length.
Input: Transmissible gastroenteritis virus (TGEV) of pigs and porcine epidemic diarrhea virus (PEDV) are two porcine coronaviruses in the genus Alphacoronavirus of the Coronavirinae subfamily in the Coronaviridae family within the order Nidovirales. Based on sequence heterogeneity, PED viruses are tentatively categorized as "classical" and "emerging" strains. The classical strains include PED viruses identified between 1970s to 2010, whereas PED viruses isolated after 2010 are referred to as emerging strains. The emerging strains are further divided into "non-S INDEL (insertions and deletions)" and "S INDEL" strains on the basis of the spike (S) protein sequences and virulence in piglets. Another proposal classifies PED viruses into up to five genotypes. The enveloped virions of coronaviruses are spherical and/or pleomorphic with diameters of 144.8 ± 7.2 nm for TGEV (PUR46-MAD strain) and 95-190 nm for PEDV (CV777 strain). Viral envelope contains the spike (S), membrane (M), and envelope (E) proteins. Homotrimeric S protein complexes form the distinctive "corona-like" structure on the surface of the virions. Within the envelope, there exists a nucleocapsid consisting of the nucleocapsid (N) protein and viral genomic RNA. Both TGEV and PEDV have a typical genomic organization of coronaviruses. The positive-sense, single-stranded RNA genome is approximately 28 kb in length with a 5′ cap structure and a 3′ polyadenylated tail. The coding sequence is flanked by untranslated regions (UTRs) at 5′ and 3′ ends. The N-terminal two-thirds of the genome contain one major open reading frame ORF1a encoding replicase polyprotein pp1a. A -1 frameshift just 5′ to the stop codon of ORF1a gives rise to ORF1b encoding a much longer replicase polyprotein pp1ab. These polyproteins are cleaved into 16 nonstructural proteins (nsps) mostly involved in viral RNA replication. The rest 10-kb genome codes for structural proteins S, M, E, and N, as well as accessory proteins with various functions (Fig. 1) . TGEV encodes three accessory proteins, whereas PEDV encodes one.

Transmissible Gastroenteritis Virus of Pigs and Porcine Epidemic Diarrhea Virus