[Characterization of polyhedrosis virus strain, isolated from field collected diseased larvae of the cabbage loopervirus Trichoplusia neither (Lepidopera: Noctuidae) in the center of Mexico] | Caracterizacion de cepas silvestres de virus de poliedrosis nuclear aisladas de Trichoplusia ni (Lepidoptera: Noctuidae) en el centro de Mexico

English. This paper reports the characterization of five nuclear polyhedrosis virus strain, isolated from field collected diseased larvae of the cabbage looper, Trichoplusia ni (Huebner), at the Bajio region in central Mexico. Isolates LBIV-4, 5 and 6 exhibited statistically higher virulence than the standard AcNPV. Isolate LBIV-6 showed and LC sub50 as low as 0.098 pib/mm*2. Ultraestructural observations made under both scanning and transmission electron microscopy, as well as the restriction patterns generated with restriction enzymes Eco RI, Hind III and Bam HI, revealed the presence of two NPV types attacking T. ni in this region; one type exhibits large, cubic polyhedra, with multiple virions and restriction patterns very similar to those of AcNPV, whereas the second type displays smaller, tetrahedral polyhedra, with single virions, restriction patterns very different to those of AcNPV, and higher virulence. A possible endemism of this second type is discussed. According to ultrastructural observations and restriction patterns, it is inferred that isolates LBIV-5 and 6 are mixtures of both NPV types. Due to their highest virulence a possible synergism is suggested

Spanish; Castilian. Se presenta la caracterizacion de 5 cepas de virus de poliedrosis nuclear, aisladas en campos agricolas del Bajio mexicano a partir de larvas enfermas del falso medidor de la col, Trichoplusia ni (Hubner). Las cepas LBIV-4, 5 y 6 mostraron niveles de virulencia estadisticamente superiores al de la cepa estandar VPNAc. La cepa LBIV-6 destacan con una CL sub50 de 0.098 cpi/mm*2. Las observaciones ultraestructurales, tanto en microscopia electronica de barrido como de transmision, asi como los patrones mostrados en geles de agarosa por los fragmentos producidos por la digestion del genoma con las endonucleasas eco RI, Hind III y BamHI, revelan que existen 2 tipos basicos de virus de poliedrosis nuclear atacando a T. ni en la region; el primero presenta un poliedro grande, casi cubico, con viriones multiples y patrones de restriccion muy similares a los del estandar VPNAc, mientras que el segundo muestra poliedros casi tetraedricos, con una cara triangular principal, con viriones simples, patrones de restriccion diferentes a los del VPNAc y mayor virulencia. Se discute el posible endemismo del segundo tipo (VPNS). De acuerdo a las observaciones ultraestructurales, asi como a los patrones de restriccion, se deduce que las cepas LBIV-5 y 6 presentan mezclas de ambos tipos y por ser las mas virulentas, se sugiere un posible sinergismo entre ellas