Name: Olga Stepanova

Email: solar-ua@ya.ru

Author: Olga A. Stepanova

Author affiliation: Institute of Biology of Southern seas of Natl. Academy of Sci., Sevastopol, UKRAINE

Abstract title: Methodical Improvement of Isolation Phaeodactylum tricornutum Virus from Samples of Marine Water

Absstract:

Understanding of the ecology of viruses in hydrosphere is based on different results received with using various methods. The study of the characteristics of different viral strains enriches information about aquatic viral ecology. Therefore creation of methods of isolation of viruses and improvement of these methods are always live issue and do not lose the urgency. The aim of our study was the definition of increase of possibility of isolation of viruses, on an example of isolation of strains of Phaeodactylum tricornutum Virus (PtV), from samples of marine water with taking into consideration the some aspects of interaction between viruses and hosts in marine environment. For isolation of algaeviruses we used method (patent 65864A UA, N2003065499). Samples of marine water we selected (in volume of 1 liter = 1000 ml) from 4 various stations of water area of Black sea near Sevastopol in December 2007, and in February, in March, in April and in June 2008. We did twice the isolation of viruses from samples of marine water - at once after taking samples (fresh marine water) and after 7-20 days storage of samples of water in conditions of room temperature and light. All 20 samples of fresh marine water and 20 samples of water after storage were studied. From 20 samples of fresh marine water we isolated 7 strains of PtV. But from 20 samples of water after storage we isolated 16 strains of PtV. In case of isolation of algaeviruses from samples of fresh marine water their titer was defined up to 10 in 1 degree of infectious units in 1 ml of water (i.e. not less than 1 virion in 1 ml of marine water) and only in March 2008 we fixed titer as 10 in 3 degrees of infectious units in 1 ml. Infectious titer of algaeviruses isolated from samples of water after storage was within from 10 in 3 up to 10 in 4 degrees of infectious units in 1 ml of water (i.e. not less than 10 in 3 - 10 in 4 degrees virions in 1 ml of marine water). Our results showed that using both samples of fresh marine water and of water after storage will give the best possibility of isolation of algaeviruses. It is logical to assume, that the increase (on 3-4 degrees) of number of viruses in samples of water after storage 7-20 days is a result of an active viral infection of individual cells of their hosts. So, if the viruses was not found in 1-2 ml of fresh marine water, we think their concentration was less than 100 virions in 1 liter (i.e. 1 virion in 100 ml). But after several days of storage of this water the active virus infection of algae results in increase of number of viruses up to 10 in 3 or 4 degrees in 1 ml of this sample of water. The sharp increase of number of viruses allows carrying out their more successful isolation by biological methods with using of indicatory algae cultures. Thus, on the basis of the received results we offered to improve the method of isolation of viruses by additional testing of marine water after storage during 7-20 days (at room temperature and light). Our offer takes into account features of ecology of viruses and hosts in marine environment.