Virus production in Phaeocystis pouchetii and its relation to host cell growth and nutrition

In this experimental study we investigated how growth conditions and physiological status of the marine haptophyte Phaeocystis pouchetii affect its interaction with the lytic virus PpV01. A simple mathematical model describing the infection, the lysis of algae and the production of new viral particles was developed as an aid for analyzing and understanding the interaction between host and virus. P. pouchetii was susceptible to virus infection in all stages of growth. Nutrient or light limitation of algal growth did not inhibit viral reproduction and cell lysis. Neither the infectivity of the progeny viruses produced nor the length of the lytic cycle appeared to be affected by the host cells' growth condition. However, possible effects may have been obscured by low accuracy of infective virus counts or by low sampling frequency. The host cells' growth conditions did have a significant impact on burst size, A maximum of 510 viruses produced per infected host cell was found in exponentially growing cultures, while low burst size (minimum 15) was found in stationary phase cultures, in nutrient depleted cultures and in light Limited cultures.