Biological function of the rotavirus protein VP4: Observations on porcine isolates from China

Abstract

Rotaviruses isolated from pigs in China were grown in MA104 cells. One tissue-culture-adapted isolate consisted of two subpopulations (variants), the RNA profiles of which differed in the relative migration of RNA segment 4 only. The variants were separated by plaque purification and by recovery from limiting dilutions and remained genetically stable. The variant possessing the slower migrating RNA segment 4, called 4S, grew faster and formed large plaques after 4-6 days incubation, whereas the variant possessing the faster migrating RNA segment 4, called 4F, grew more slowly and formed only microscopic plaques after 10-14 days incubation. The protein product of the 4F RNA occurred in much lower concentration in infected cells than the product of the 4S RNA. The RNA segments 4 of the two variants were found to be closely related when tested by dot hybridization under stringent conditions. The 4S RNA is more resistant to denaturation with methyl mercuric hydroxide than is the 4F RNA. The relevance of these findings to the biological functions of rotaviruses is discussed.

Genome rearrangements in porcine rotaviruses: biochemical and biological comparisons between a supershort strain and its standard counterpart

“…Our observation that the CC86 strain produces large plaques is of interest as previously only the gene product of segment 4 has been associated with protease-enhanced plaque formation (Estes et al, 1981 ;Kalica et al, 1983;Haddow et al, 1989;Burns et al, 1989), and this phenotype was initially thought to segregate only with this single genomic segment. This conclusion has been questioned by recent results which indicate that segments 4 and 9 may be necessary, in certain genetic backgrounds, to produce large plaques.…”

Sequence analysis of two porcine rotaviruses differing in growth in vitro and in pathogenicity: distinct VP4 sequences and conservation of NS53, VP6 and VP7 genes

“…PRV variants 4F and 4S (Ni et al, 1986;Haddow et al, 1989) were propagated in the presence of 0.5 jag/ml of trypsin (type IX; Sigma).…”

“…Electropherotyping of the cell cultureadapted rotavirus RNA on polyacrylamide gels revealed a normal pattern except for the presence of a double gene 4 band. Two variants, designated 4F (for fast migrating gene 4) and 4S (for slow migrating gene 4) that showed electropherotypes differing only in the migration of gene 4 were subsequently isolated from this mixture by plaque purification and limiting dilutions (Haddow et al, 1989). Variants 4F and 4S were found to differ greatly in their in vitro growth properties: 4S grew faster, yielded a final titre 10-to 30-fold higher than 4F, and produced large plaques 4 to 5 days after infection, whereas 4F produced only small plaques after 10 to 12 days.…”

The pathogenicity of two porcine rotaviruses differing in their in vitro growth characteristics and genes 4

“…From this, two variants have been purified by plaquing and limiting dilution techniques (Haddow et al, 1989). The variants differ notably in the electrophoretic migration of gene 4, whereas the other 10 genes comigrate.…”

“…The two variants also differ markedly in their growth kinetics and plaque formation in MA104 cells. Variant 4F ffast migrating gene 4) grows slowly and produces only small plaques after 10 to 12 days (Haddow et al, 1989), whereas variant 4S (~low migrating gene 4) grows faster and to higher titres and produces large plaques 4 to 5 days after infection.…”