Comparison of the usefulness of the CACO-2 cell line with standard substrates for isolation of swine influenza A viruses.
Influenza A virus isolation is undertaken routinely in embryonated chicken eggs, but to improve virus detection various cell lines can be used. The CACO-2 cell line was compared to the MDCK cell line and embryonated chicken eggs for the isolation of H1N1, H1N2, H3N2 swine influenza A virus subtypes from clinical specimens. From 2006 to 2008, 104 influenza A samples found positive by PCR from 42 respiratory outbreaks in Italian swine farms were examined by virus isolation. Sixty swine influenza A viruses were isolated (16 H1N1, 28 H1N2 and 16 H3N2) and their growth behaviour on the different substrates was examined. 16/16 H1N1, 28/28 H1N2 and 8/16 of H3N2 viruses were isolated from the CACO-2 cell line, while 7/16 H1N1, 3/28 H1N2 and 16/16 H3N2 viruses were isolated using embryonated chicken eggs. Only 9/16 H1N1, 1/28 H1N2 and 6/16 H3N2 viruses replicated in MDCK cells. A link was found between viral hemagglutinin and the isolation rate on the various substrates. The CACO-2 line was statistically more sensitive (Fisher's exact test, p<0.01) compared to the MDCK cells and embryonated chicken eggs for the isolation of H1N1 and H1N2 subtypes. In contrast influenza A H3N2 virus was isolated more readily in embryonated chicken eggs than in cultured cells (Fisher's exact test, p<0.01).
Istituto Zooprofilattico Sperimentale della Lombardia e dell'Emilia Romagna Bruno Ubertini, Sezione Diagnostica di Parma, via dei Mercati 13/A, 43100 Parma, Italy. chiara.chiapponi@izsler.it
Chiara
C
Chiapponi
Irene
I
Zanni
Chiara
C
Garbarino
Giuseppe
G
Barigazzi
Emanuela
E
Foni
D000818:Animals; D018938:Caco-2 Cells; D002642:Chick Embryo; D004285:Dogs; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000302:isolation & purification*; D057221:Influenza A Virus, H1N2 Subtype / Q000235:genetics / Q000302:isolation & purification*; D053122:Influenza A Virus, H3N2 Subtype / Q000235:genetics / Q000302:isolation & purification*; D007251:Influenza, Human / Q000453:epidemiology* / Q000821:virology; D016133:Polymerase Chain Reaction; D014776:Virus Cultivation / Q000379:methods*