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. 2021 Sep 22;13(10):1895.
doi: 10.3390/v13101895.

Generation of Variability in Chrysodeixis includens Nucleopolyhedrovirus (ChinNPV): The Role of a Single Variant

Eduardo Aguirre  1 , Inés Beperet  2 , Trevor Williams  3 , Primitivo Caballero  1   2
Affiliations

Generation of Variability in Chrysodeixis includens Nucleopolyhedrovirus (ChinNPV): The Role of a Single Variant

Eduardo Aguirre et al. Viruses. .

Abstract

The mechanisms generating variability in viruses are diverse. Variability allows baculoviruses to evolve with their host and with changes in their environment. We examined the role of one genetic variant of Chrysodeixis includens nucleopolyhedrovirus (ChinNPV) and its contribution to the variability of the virus under laboratory conditions. A mixture of natural isolates (ChinNPV-Mex1) contained two genetic variants that dominated over other variants in individual larvae that consumed high (ChinNPV-K) and low (ChinNPV-E) concentrations of inoculum. Studies on the ChinNPV-K variant indicated that it was capable of generating novel variation in a concentration-dependent manner. In cell culture, cells inoculated with high concentrations of ChinNPV-K produced OBs with the ChinNPV-K REN profile, whereas a high diversity of ChinNPV variants was recovered following plaque purification of low concentrations of ChinNPV-K virion inoculum. Interestingly, the ChinNPV-K variant could not be recovered from plaques derived from low concentration inocula originating from budded virions or occlusion-derived virions of ChinNPV-K. Genome sequencing revealed marked differences between ChinNPV-K and ChinNPV-E, with high variation in the ChinNPV-K genome, mostly due to single nucleotide polymorphisms. We conclude that ChinNPV-K is an unstable genetic variant that is responsible for generating much of the detected variability in the natural ChinNPV isolates used in this study.

Keywords: ChinNPV; Chrysodeixis includens; SNPs; concentration; prevalence; variability.

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Conflict of interest statement

The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.

Figures

Figure 1
Figure 1
Prevalence of ChinNPV variants by dominant REN profile in Chysodeixis includens fifth instar larvae inoculated with ChinNPV-Mex1 OBs at concentrations of (A) 108, (B) 5 × 106, (C) 5 × 105, (D) 104 OBs/mL. Circular charts represent the proportions of dominant REN profiles similar or different to that of ChinNPV-K OBs recovered from virus-killed larvae (indicated as ChinNPV-K and Other variants, respectively). A bar chart is depicted next to each circular chart, specifying which REN profiles were observed among the other variants. The y-axis indicates the number of insects that showed a particular dominant REN profile in the progeny OBs and the x-axis indicates each of the REN profiles observed in descending frequency; n indicates the number of insects analyzed.
Figure 2
Figure 2
Prevalence of ChinNPV-K REN profiles in OB samples from virus-killed Chrysodeixis includens fifth instar larvae after inoculation with ChinNPV-K. Circular charts represent the proportions of REN profiles of ChinNPV-K and other variants in progeny OBs recovered from virus-killed larvae that had been inoculated with (A) 108 OBs/mL or (B) 5 × 104 OBs/mL. A bar chart is depicted next to each circular chart to indicate which REN profiles were recovered among the other variants. The y-axis indicates the number of insects that showed a particular dominant REN profile in the progeny OBs and the x-axis indicates each of the REN profiles observed in descending frequency; n indicates the number of insects analyzed. Novel REN profiles were classified as unknown and are shown as “?” in bar charts.
Figure 3
Figure 3
Prevalence of REN profiles in Chrysodeixis includens fifth instar larvae that died following inoculation of mixtures of variant K OBs and variant E OBs at high inoculum concentration (total concentration 108 OBs/mL). Inocula were (A) 1 × 108 K, (B) 108 K + 102 E, (C) 108 K + 105 E, (D) 9 × 107 K + 107 E, (E) 5 × 107 K + 5 × 107 E OBs/mL, (F) 1 × 107 K + 9 × 107 E OBs/mL, (G) 105 K + 108 E OBs/mL, (H) 102 K + 108 E OBs/mL and (I) 108 E OBs/mL. Circular charts represent the proportions of REN profiles of ChinNPV-K and other variants recovered from dead larvae. A bar chart depicted next to each circular chart indicates which REN profiles were recovered among the other variants and their frequency. The y-axis indicates the number of insects that showed a particular dominant REN profile in the progeny OBs and the x-axis indicates each of the REN profiles observed in descending frequency; n indicates the number of insects analyzed. Novel REN profiles were classified as unknown and are shown as “?” in bar charts.
Figure 4
Figure 4
Prevalence of ChinNPV-K and ChinNPV-E REN profiles in Chrysodeixis includens fifth instar larvae that died following inoculation with variant mixtures (K + E) at low inoculum concentration (total concentration 5 × 104 OBs/mL). Inocula were (A) 2.5 × 104 K + 2.5 × 104 E OBs/mL, (B) 5 × 103 K + 4.5 × 104 E OBs/mL. Circular charts represent the proportions of REN profiles of ChinNPV-E, ChinNPV-K and other variants recovered from dead larvae. A bar chart depicted next to each circular chart indicates which REN profiles were recovered among the other variants and their frequency. The y-axis indicates the number of insects that showed a particular dominant REN profile in the progeny OBs and the x-axis indicates each of the REN profiles observed in descending frequency; n indicates the number of insects analyzed. Novel REN profiles were classified as unknown and are shown as “?” in bar charts.
Figure 5
Figure 5
Prevalence of REN profiles in Chrysodeixis includens fifth instar larvae that died following inoculation with (A) 108 OBs/mL or (B) 5 × 104 OBs/mL of a pooled OB inoculum derived from insects that had been originally inoculated with ChinNPV-K variant OBs. Circular charts represent the proportion of REN profiles of ChinNPV-K and other variants recovered from dead larvae. A bar chart is depicted next to each circular chart specifying which REN profiles were recovered among the other variant profiles and their frequency. The y-axis indicates the number of insects that showed a particular dominant REN profile in the progeny OBs and the x-axis indicates each of the REN profiles observed in descending frequency; n indicates the number of insects analyzed. Novel REN profiles were classified as unknown and are shown as “?” in bar charts.
Figure 6
Figure 6
Prevalence of REN profiles from virus-killed larvae that were infected by injection of plaque picks derived from BVs in hemolymph samples obtained following inoculation of Chrysodeixis includens fifth instars with ChinNPV-K pure variant OBs. New genotypes whose REN profiles did not match any of the previous studied variants were included in an unknown group shown as “?”; n indicates the number of plaque picks used to inoculate insects. The y-axis indicates the prevalence (%) of insects that produced progeny OBs with a particular dominant REN profile and the x-axis indicates each of the observed REN profiles in decreasing frequency.
Figure 7
Figure 7
Prevalence of REN profiles from virus-killed Chrysodeixis includens fifth instars that died following injection of plaque picks derived from ChinNPV-K pure variant ODVs. New genotypes whose REN profiles did not match any of the previous studied variants were included in an unknown group shown as “?”; n indicates the number of plaque picks used to inoculate insects. The y-axis indicates the prevalence (%) of insects that produced progeny OBs with a particular dominant REN profile and the x-axis indicates each of the observed REN profiles in decreasing frequency.
Figure 8
Figure 8
Schematic representation of ChinNPV-K genome ORFs. Vertical bars represent the number of cumulative SNPs in each ORF in pink for ChinNPV-K and green for ChinNPV-E, resulting in different heights according to the number of SNPs. Bars labelled with asterisks indicate the highest number of SNPs detected, which was 22 SNPs per ORF. Only the ChinNPV-K genome is depicted due to the high similarity between the ChinNPV-K and ChinNPV-E ORF length and distribution. The three ORFs in red represent ORFs that are not present in the ChinNPV genomes sequenced previously.
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References

    1. Harrison R.L., Herniou E.A., Jehle J.A., Theilmann D.A., Burand J.P., Becnel J.J., Krell P.J., van Oers M.M., Mowery J.D., Bauchan G.R., et al. ICTV Virus Taxonomy Profile: Baculoviridae. J. Gen. Virol. 2018;99:1185–1186. - PubMed
    1. Sanjuán R., Domingo-Calap P. Mechanisms of viral mutation. Cell. Mol. Life Sci. 2016;73:4433–4448. - PMC - PubMed
    1. Erlandson M. Genetic variation in field populations of baculoviruses: Mechanisms for generating variation and its potential role in baculovirus epizootiology. Virol. Sin. 2009;24:458–469.
    1. Gebhardt M.M., Eberle K.E., Radtke P., Jehle J.A. Baculovirus resistance in codling moth is virus isolate-dependent and the consequence of a mutation in viral gene pe38. Proc. Natl. Acad. Sci. USA. 2014;111:15711–15716. - PMC - PubMed
    1. Gilbert C., Chateigner A., Ernenwein L., Barbe V., Bézier A., Herniou E.A., Cordaux R. Population genomics supports baculoviruses as vectors of horizontal transfer of insect transposons. Nat. Commun. 2014;5:3348. - PMC - PubMed

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