(MDPI, 2021) Ricarte Bermejo, Adriana; Simón de Goñi, Oihane; Fernández González, Ana Beatriz; Williams, Trevor; Caballero Murillo, Primitivo; Institute for Multidisciplinary Research in Applied Biology - IMAB
Enhancins are metalloproteinases that facilitate baculovirus infection in the insect midgut.
They are more prevalent in granuloviruses (GVs), constituting up to 5% of the proteins of viral
occlusion bodies (OBs). In nucleopolyhedroviruses (NPVs), in contrast, they are present in the
envelope of the occlusion-derived virions (ODV). In the present study, we constructed a recombinant
Autographa californica NPV (AcMNPV) that expressed the Trichoplusia ni GV (TnGV) enhancin 3
(En3), with the aim of increasing the presence of enhancin in the OBs or ODVs. En3 was successfully
produced but did not localize to the OBs or the ODVs and accumulated in the soluble fraction of
infected cells. As a result, increased OB pathogenicity was observed when OBs were administered
in mixtures with the soluble fraction of infected cells. The mixture of OBs and the soluble fraction
of Sf9 cells infected with BacPhEn3 recombinant virus was ~3- and ~4.7-fold more pathogenic than
BacPh control OBs in the second and fourth instars of Spodoptera exigua, respectively. In contrast,
when purified, recombinant BacPhEn3 OBs were as pathogenic as control BacPh OBs. The expression
of En3 in the soluble fraction of insect cells may find applications in the development of virus-based
insecticides with increased efficacy.
