title: Horizontal and vertical transmission of wild-type and recombinant Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus.
abstract: Transmission plays a central role in the ecology of baculoviruses and the population dynamics of their hosts. Here, we report on the horizontal and vertical transmission dynamics of wild-type Helicoverpa armigera single-nucleocapsid nucleopolyhedrovirus (HaSNPV-WT) and a genetically modified variant (HaSNPV-AaIT) with enhanced speed of action through the expression of an insect-selective scorpion toxin (AaIT). In caged field plots, horizontal transmission of both HaSNPV variants was greatest when inoculated 3rd instar larvae were used as infectors, transmission was intermediate with 2nd instar infectors and lowest with 1st instar infectors. Transmission was greater at a higher density of infectors (1 per plant) than at a lower density (1 per 4 plants); however, the transmission coefficient (number of new infections per initial infector) was lower at the higher density of infectors than at the lower density. HaSNPV-AaIT exhibited a significantly lower rate of transmission than HaSNPV-WT in the field cages. This was also the case in open field experiments. In the laboratory, the vertical transmission of HaSNPV-AaIT from infected females to offspring of 16.7+/-2.1% was significantly lower than that of HaSNPV-WT (30.9+/-2.9%). Likewise, in the field, vertical transmission of HaSNPV-AaIT (8.4+/-1.1%) was significantly lower than that of HaSNPV-WT (12.6+/-2.0%). The results indicate that the recombinant virus will be transmitted at lower rates in H. armigera populations than the wild-type virus. This may potentially affect negatively its long-term efficacy as compared to wild-type virus, but contributing positively to its biosafety.
authors.affiliation: Joint-Laboratory of Invertebrate Virology, Key Laboratory of Molecular Virology and State Key Laboratory of Virology, Wuhan Institute of Virology, Chinese Academy of Sciences, Wuhan, 430071 Hubei, China.
authors.forename: Mingzhe
authors.initials: M
authors.lastname: Zhou
authors.forename: Xiulian
authors.initials: X
authors.lastname: Sun
authors.forename: Xincheng
authors.initials: X
authors.lastname: Sun
authors.forename: Just M
authors.initials: JM
authors.lastname: Vlak
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Hu
authors.forename: Wopke
authors.initials: W
authors.lastname: van der Werf
mesh_terms: D000818:Animals; D018562:Disease Transmission, Infectious; D005260:Female; D018445:Infectious Disease Transmission, Vertical; D007915:Lepidoptera / Q000821:virology*; D017924:Nucleopolyhedroviruses / Q000502:physiology*; D010572:Pest Control, Biological; D011994:Recombinant Proteins; D012604:Scorpion Venoms / Q000235:genetics; D014777:Virus Diseases / Q000635:transmission*
chemical_list: D011994:Recombinant Proteins; D012604:Scorpion Venoms; C065634:AaIT neurotoxin, Androctonus australis