Sorologia e sobrevivência do vírus do amarelo letal do mamoeiro

Abstract

Resumo -O vírus do amarelo letal do mamoeiro (Papaya lethal yellowing virus, PLYV) é responsável por uma das principais doenças do mamoeiro (Carica papaya) no Nordeste brasileiro. O PLYV pode ser transmitido através do solo, água, instrumento de corte e mãos contaminadas. A presente pesquisa teve como objetivo estudar as características biológicas, sorológicas e físicas de um isolado do vírus e avaliar sua sobrevivência em tecido seco infetado. O PLYV foi detectado por "Enzyme linked immunosorbent assay" (ELISA) indireto e isolado em mudas de mamoeiro, através da inoculação mecânica. A sobrevivência do PLYV em folhas e raízes secas de mamoeiro infetado foi avaliada por sorologia e inoculação em plantas sadias. A presença do vírus foi detectada em folhas e raízes de mamoeiro secas, indicando que o vírus pode permanecer ativo em restos de cultura por até 120 dias. A purificação do PLYV permitiu a obtenção de 309.5 mg de vírus/kg de folha e o anti-soro obtido mostrou-se altamente específico, com títulos de 1:128 em dupla difusão em Agar e 1:1.024.000 em Elisa indireto. Estudos das propriedades físicas do PLYV em mamoeiro revelaram um ponto de inativação térmica (PIT) em torno de 80 ºC, um ponto máximo de diluição (PMD) de ac. 10-6 e uma longevidade in vitro (LIV) acima de 50 dias. Palavras-chave -Carica papaya. PLYV. Papaya lethal yelloing virus.Abstract -The Papaya lethal yellowing virus (PLYV) is responsible for one of the most important disease of papaya (Carica papaya) in the Northeast of Brazil. The PLYV can be transmitted through the soil, irrigation water, agriculture tools and contaminated hands. The present research had the objective to characterize biologically, serologically and physically a PLYV isolate and evaluates how long it survives in infected dried tissues. The PLYV was identified by indirect enzyme linked immunoabsorbent assay (ELISA), isolated in young papaya plants by mechanical inoculations and maintained at green house conditions for virus purification. Approximately 309.5 mg of virus was purified per kg of infected papaya leaves and a polyclonal antiserum was obtained from an immunized rabbit. The antiserum obtained was shown to be highly specific to PLYV with a titer of 1:128 in double immune-diffusion and a titer of 1:1.024.000 in indirect ELISA. The virus was detected in dried roots and leaves maintained at room temperature up to 120 days, confirming its high stability within nonliving plant tissues, which could explain its dissemination by contaminated hands, tools, water and soil. The physical properties determined for the virus revealed a thermal inactivation point of 80 o C, longevity in vitro over 50 days and dilution end point ac. of 10 -6.

Biological stability of a strain of Cowpea severe mosaic virus over 20 years

“…Macaibo leaves by a similar method used by Nascimento et al (2010) to purify Papaya lethal yellowing virus from infected papaya (Carica papaya L.), using n-Butanol for plant sap clarification and virus particles precipitation with polyethylene glycol MW 6,000 (PEG), followed by a further ultra-centrifugation for virus particles precipitation and concentration. The final pellet from the high speed centrifugation was resuspended in 0.02 M Tris buffer pH 7.5, and the virus purity and concentration was evaluated in an ultraviolet spectrophotometer VARIANT DMS -70, using wavelength range of 220 to 340 nm.…”