TABLE 1.

Brief clinical histories and virus isolation methods for the swine H1N2 viruses analyzed in this study

Virus	Clinical history	Virus isolation and propagation methods	GenBank reference no.
A/Swine/Minnesota/55551/00	Unthriftiness and inconsistent growth rates among nursery and grower pigs (∼2-10 wk old); concurrent A. pp. infectionb; PCV2c and PRRSVd positive and M. hyo.e negative	MDCK cell culture isolation from lung tissue from nursery pigs and MDCK cell propagation with TPCK-trypsina	AF455678, AF455686, AF455694, AF455702, AF455710, AF455718, AF455726, AF455734
A/Swine/Indiana/P12439/00	Acute respiratory disease with coughing and lethargy among 30 of 300 grower pigs (∼9-10 wk old) with 2 deaths; M. hyo. positiveg and PRRSV negative	PT-1 cellsf isolation from pooled lung tissues and MDCK cell propagation with TPCK-trypsin	AF455680, AF455688, AF455696, AF455704, AF455712, AF455720, AF455728, AF455736
A/Swine/Ohio/891/01	Prolonged outbreak (6 months) of disease on a farm with 700 sows weaning ∼300 piglets/week; high fevers, coughing and diarrheal disease (100% morbidity), and enhanced mortality in pigs 3 to 6 wk old	MDCK cell culture isolation from lung tissue and MDCK cell propagation with TPCK-trypsin	AF455675, AF455683, AF455691, AF455699, AF455707, AF455715, AF455723, AF455731
A/Swine/North Carolina/93523/01	Acute respiratory disease, increased (twofold) mortality, and reduced rates of weight gain in nursery to grower pigs (∼8 wk old)	MDCK cell culture isolation from lung tissue and MDCK cell propagation with TPCK-trypsin	AF455677, AF455685, AF455693, AF455701, AF455709, AF455717, AF455725, AF455733
A/Swine/North Carolina/98225/01	Acute respiratory disease and enhanced (0.5-1.0% increase) mortality among grower to finisher pigs (∼12 wk old)	MDCK cell culture isolation from lung tissue and MDCK cell propagation with TPCK-trypsin	AF455676, AF455684, AF455692, AF455700, AF455708, AF455716, AF455724, AF455732
A/Swine/Illinois/100084/01	Acute respiratory disease with coughing among 5 of 75 finisher pigs (∼7 mo old), with 2 deaths	MDCK cell culture isolation from lung tissue and MDCK cell propagation with TPCK-trypsin	AF455682, AF455690, AF455698, AF455706, AF455714, AF455722, AF455730, AF455738
A/Swine/Illinois/100085a/01	Coughing of several weeks duration (no improvement with oral antibiotics) among 200 of 1000 young grower pigs (∼5 wk old)	MDCK cell culture isolation from lung tissue and MDCK cell propagation with TPCK-trypsin	AF455681, AF455689, AF455697, AF455705, AF455713, AF455721, AF455729, AF455737
A/Swine/Iowa/930/01	Sneezing and coughing, progressing to severe dyspnea among 700 of 700 9-12-wk-old pigs	MDCK cell culture isolation from lung tissue and MDCK cell propagation with TPCK-trypsin	AF455679, AF455687, AF455695, AF455703, AF455711, AF455719, AF455727, AF455735

^aMDCK, Madin-Darby canine kidney cells; TPCK, tosylsulfonyl phenylalanyl chloromethyl ketone-treated trypsin.

^bActinobacillus pleuropneumoniae (A. pp.) by bacterial culture of lung tissue.

^cPorcine circovirus type 2 (PCV2) by PCR assay on lung tissue.

^dPorcine reproductive and respiratory syndrome virus (PRRSV) by virus isolation on MARC-145 cells.

^eMycoplasma hyopneumoniae (M. hyo.) by PCR assay on lung tissue.

^fPorcine embryonic testicle cells (American BioResearch).

^gMycoplasma hyopneumoniae by fluorescent antibody assay on lung tissue.