Some bacterial viruses shut off host DNA replication to arrest host growth. The advantage for the virus might be to have all the pool of nucleotides available for its own replication.
Bacteriophage N4 (Gp8 protein) and Staphylococcus bacteriophages for example shut off the host DNA replication by inhibiting the processivity clamp of the replicating polymerase 
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Competition of bacteriophage polypeptides with native replicase proteins for binding to the DNA sliding clamp reveals a novel mechanism for DNA replication arrest in Staphylococcus aureus
Adam Belley, Mario Callejo, Francis Arhin, Mohammed Dehbi, Ibtihal Fadhil, Jing Liu, Geoffrey McKay, Ramakrishnan Srikumar, Pascale Bauda, Dominique Bergeron, Nhuan Ha, Michael Dubow, Philippe Gros, Jerry Pelletier, Greg Moeck
Mol. Microbiol. November 2006; 62: 1132-1143
A phage-encoded inhibitor of Escherichia coli DNA replication targets the DNA polymerase clamp loader
Sho T Yano, Lucia B Rothman-Denes
Mol. Microbiol. March 2011; 79: 1325-1338
The bacteriophage lambda DNA replication protein P inhibits the oriC DNA- and ATP-binding functions of the DNA replication initiator protein DnaA of Escherichia coli
Indrani Datta, Subrata Sau, Alok Kumar Sil, Nitai C Mandal
J. Biochem. Mol. Biol. January 31, 2005; 38: 97-103
Roles of genes 38, 39, and 40 in shutoff of host biosyntheses during infection of Bacillus subtilis by bacteriophage SPO1
Charles R Stewart, Tameson K S Yip, Bati Myles, Laura Laughlin
Virology September 30, 2009; 392: 271-274
Phage Lambda P protein: trans-activation, inhibition phenotypes and their suppression
Sidney Hayes, Craig Erker, Monique A Horbay, Kristen Marciniuk, Wen Wang, Connie Hayes
Viruses February 2013; 5: 619?653
