Parasites are an important cause of mortality in many different organisms, and this affects the functioning of ecosystems and the entire biosphere. However, the strategies developed by parasites to efficiently infect host populations have barely been studied and many questions are still unsolved: What activates them? How is their growth and development into the host? What are the changes of the host induced by the parasite?
A study led by the Institute of Marine Sciences presents a detailed description of the infection process of marine microalgae by the parasite Parvilucifera sinerae, recently found and described in the Catalan seacoast. In the study, different methods are used to understand how this parasite infects the host, how it develpos, and the dynamics of the infection, including aspects such as the speed of transmission among the individuals of a population.
The work reveals that the latent parasite is activated in the presence of living cells of the host (the microalgae). Then, the parasite destroys the host’s cell content and proliferates into it. It has also been seen that several aspects of P. sinerae infections, such as the development and multiplication of the parasite, are common with Plasmodium falciparum, the parasite that causes malaria in humans.
Elisabet Alacid, a doctoral student in the Department of Marine Biology and Oceanography of the ICM and first author of the study, explains: "Despite the partial similarities between the two parasites, having this simple model of host-parasite (harmless for humans) in a culture can be used as a laboratory model for studying in a safe way some aspects of the malaria parasite. "
Very little is known about natural parasites of marine protists, but since the existence of a greater interest around this topic, and the new perspectives on their influence on the functioning of ecosystems, many of them have been detected in sea water and marine sediments. So far, only three groups of parasites of marine protists and their mechanisms of infection are partly known. With this work, the entire infection cycle of one of these groups have been described in detail for first time. The work describes the process since the parasite infects the host until the new zoospores are released to restart the cycle of infection. This is also the first description of the population dynamics of the infection caused by this group.
Esther Garcés, director of the study states: "It is fascinating to see how nature uses successful mechanisms in many different environments The study of a marine host-parasite model helps us to understand the universal mechanisms driving this interaction. This indicates that the underlying mechanisms of the relationship between these organisms are common and repetitive in nature. The ecological model we have found is similar to that of plagues in agriculture or epidemics in medicine, so the results of this research are valid for other disciplines. "
Paper:
Elisabet Alacid, Albert Reñé, and Esther Garcés. New Insights into the Parasitoid Parvilucifera sinerae Life Cycle: The Development and Kinetics of Infection of a Bloom-forming Dinoflagellate Host. Protist DOI: 10.1016/j.protis.2015.09.001 PDF