Aureococcus anophagefferens strain CCMP1851: draft genome of a second Kratosvirus quantuckense-susceptible host strain for an emerging host–giant virus model system

ABSTRACT Here, we report the draft genome of Aureococcus anophagefferens strain CCMP1851, which is susceptible to the virus Kratosvirus quantuckense. CCMP1851 complements an available genome for a virus-resistant strain (CCMP1850) isolated from the same bloom. Future studies can now use this genome to examine genetic hints of virus resistance and susceptibility.

W e assembled a draft genome for an isolate of the marine algae Aureococcus anophagefferens (Pelagophyceae) (1). A. anophagefferens strain CCMP1851 is only the second strain with a genome made public that can be infected by the "giant" virus Kratosvirus quantuckense (Nucleocytoviricota) (2)(3)(4)(5).It was isolated from the same bloom as the strain CCMP1850 (September 1998, Great South Bay, Long Island; NCMA, Bigelow), which is resistant to this virus (4,5).This resistant-susceptible pair from a similar evolutionary time enables in-lab genomic comparisons of susceptible and resistant hosts.We acknowledge the natural biology of the system, which enables single-strain monocultures deemed as "resistant" and "susceptible" to include individual cells that do not meet the requirements of "resistant" or "susceptible, " and that host resistance may occur in different ways and to different degrees.Nonetheless, this genome represents insight into two strains within a single bloom with different interactions (resistance or not) to contact with K. quantuckense.
Interestingly, the single-copy orthologous gene tree indicated a closer evolutionary relationship between CCMP1850 and CCMP1707 (Fig. 1), suggesting a stronger similarity among resistant strains despite being isolated three years apart.Future work will focus on unique genes between CCMP1851 and CCMP1850 to give context to virus resistance versus virus susceptibility to K. quantuckense.

ACKNOWLEDGMENTS
A portion of the computation for this work was performed on the University of Tennessee Infrastructure for Scientific Applications and Advanced Computing (ISAAC) computational resources.The authors would like to thank the High Performance & Scientific Computing (HPSC) group (UTK) for their support.
The study received support from the National Science Foundation (NSF) EDGE CT #1922958 and Simons Foundation (735077) to S.W.W.
Emily E. Chase performed the conceptualization, data curation, formal analysis, investigation, methodology, writing (original draft), and writing (review and editing).Alexander R. Truchon performed the investigation, methodology, and writing (review and editing).Will W. Schepens performed the investigation, writing (original draft), and writing (review and editing).Steven W. Wilhelm performed the conceptualization, funding acquisition, investigation, methodology, project administration, and writing (review and editing).JBBJCI010000000, JAFCAH000000000, JBBJCI010000000, and JAFCAI000000000), with a more distantly related outgroup (CAKKNE000000000).Bootstrap replicates are indicated at tree nodes (n = 1,000).A VT+F+G4 (i.e., variation and transition substitutions, equal frequency among nucleotides, and a gamma distribution rate with four categories) model was chosen by ModelFinder (via BIC).The tree is based on an alignment of 613,029 amino acid positions.

TABLE 1
Sequencing statistics and general assembly information of Aureococcus anophagefferens strain CCMP1851