This may not have any symptoms. If virus gets to target organ and there is large replication may get secondary viremia. In the blood virus may be free or associated with cells of the immune system. Virus in leukocytes , lymphocytes or monocytes may be protected from antibodies and other plasma components. This observation is important in HIV infection.
Viruses circulating in the blood meet two important types of cells.
See fig 6-4 for illustration of the above points. Role of macrophages. Macrophages are very efficient phagocytes and present in all parts of the body. Together with dendritic cells, macrophages are antigen processing and antigen presenting cells, and therefor play an important role in initiating the immune response. But virus can also replicate in macrophages, and there can even be enhanced replication see fig 6-5 for Kupfer cells.