Chan, A.M. and C.A. Suttle. 1994. Occurrence and isolation of viruses which infect marine Chrysochromulina spp. Abstracts American Society Limnology and Oceanography, and Phycological Society American, Miami, FL, June 1994.
Fifty-six natural virus communities were concentrated from seawater by ultrafiltration at different times of the year and from three coastal locations in south Texas. An in vivo fluorescence assay was used to screen these samples for the presence of viral pathogens that infect the marine prymnesiophyte Chrysochromulina brevifilum. Lytic pathogens were detected in 6 of 36 samples collected from the Marine Science Institute pier and 3 of 13 samples collected from a coastal lagoon (Laguna Madre), but were not detected in 7 samples collected from the Gulf of Mexico. Titers ranged from below the limit of detection (<3 viruses L-1) to 688 L-1 (95% CI 382-1236) with the highest titer occurring during April 1993 in Laguna Madre. We cloned the agent responsible for lysis of C. brevifilum from a seawater sample collected from the Institute pier. The pathogen is a tailess, polygonal, double-stranded DNA virus about 70 nm in diameter. The virus infected C. brevifilum and C. strobilus of 10 Chrysochromulina species tested but did not infect 5 other genera of Prymnesiophytes that were screened. Observations by transmission electron microscopy revealed up to about 320 virus particles within a single ultra-thin section of an infected C. brevifilum cell. DNA from these viruses can be amplified using algal-virus-specific PCR primers that were designed based on DNA sequences obtained for viruses that infect a freshwater endosymbiotic Chlorella-like alga and the prasinophyte Micromonas pusilla, suggesting that these viruses may share a common ancestry.