To elucidate the mode of viral persistence in primate lentivirus-infected individuals during combination antiretroviral therapy (cART), four simian immunodeficiency virus 239-infected monkeys were treated with cART for 1 year. The viral env genes prepared from total RNA extracted from the mesenteric lymph nodes collected at the completion of therapy were assessed by single genome amplification. Analyses of nucleotide substitutions and phylogeny revealed no viral evolution during cART. Combination antiretroviral therapy (cART) has transformed human immunodeficiency virus (HIV) infection from an incurable disease to a manageable one. It suppresses the viral burden in patients to undetectable levels (1-3), lowers the chance of viral transmission (4), increases the number of CD4 ϩ T lymphocytes (1, 2), reconstitutes immunity (5-7), and extends the life expectancy of patients (8). However, cART does not cure patients because of its inability to eradicate the virus from infected individuals (9), suggesting the existence of a viral reservoir that is refractory to cART. Its identification and eradication are therefore requisites for a functional cure for AIDS. To establish a strategy for eradication of the HIV reservoir, the mechanism of persistence of the virus must be elucidated. Two mechanisms of viral persistence have been proposed: one is ongoing cycles of viral replication despite the presence of antivirals (10), and the other is provirus integration into long-lived cells (11). Whereas previous studies concerning this issue have been extensively conducted with clinical specimens from HIV-1-infected patients, including plasma, peripheral blood mononuclear cells, and gut-associated lymphatic tissues (12-14), lymph nodes, which are epicenters of virus replication in infected individuals not undergoing therapy (15-17), have only rarely been subjected to scrutiny. In animal models of cART, in particular, the simian immunodeficiency virus (SIV)-macaque model, which allows systemic examination, the location of the viral reservoir and the mechanism of viral holding have not been studied in detail.To elucidate how the virus is maintained during cART in an animal model of anti-HIV chemotherapy, we administered a combination of nucleotide/nucleoside reverse transcriptase inhibitors (azidothymidine, lamivudine, and tenofovir disoproxil fumarate) and protease inhibitors (lopinavir with ritonavir) to four SIV239-infected rhesus macaques for 1 year (18). Although the plasma viral RNA loads of the animals were suppressed to levels below the assay detection limit during the period of chemotherapy, a systemic analysis conducted at the completion of therapy revealed viral RNA present in lymphatic tissues, especially in mesenteric and splenic lymph nodes (MLN and SLN, respectively) at high titers. Reasoning that any possible mode(s) of viral persistence should be in operation in tissues with high levels of viral RNA expression, we investigated viral genes in these tissues.It is expected that viral genes accumulate nucleotide substi...

Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP/PPM1F) and its nuclear homolog CaMKP-N (PPM1E) are Ser/Thr protein phosphatases that belong to the PPM family. CaMKP-N is expressed in the brain and undergoes proteolytic processing to yield a C-terminally truncated form. The physiological significance of this processing, however, is not fully understood. Using a wheat-embryo cell-free protein expression system, we prepared human CaMKP-N (hCaMKP-N(WT)) and the truncated form, hCaMKP-N(1–559), to compare their enzymatic properties using a phosphopeptide substrate. The hCaMKP-N(1–559) exhibited a much higher V max value than the hCaMKP-N(WT) did, suggesting that the processing may be a regulatory mechanism to generate a more active species. The active form, hCaMKP-N(1–559), showed Mn2+ or Mg2+-dependent phosphatase activity with a strong preference for phospho-Thr residues and was severely inhibited by NaF, but not by okadaic acid, calyculin A, or 1-amino-8-naphthol-2,4-disulfonic acid, a specific inhibitor of CaMKP. It could bind to postsynaptic density and dephosphorylate the autophosphorylated Ca2+/calmodulin-dependent protein kinase II. Furthermore, it was inactivated by H2O2 treatment, and the inactivation was completely reversed by treatment with DTT, implying that this process is reversibly regulated by oxidation/reduction. The truncated CaMKP-N may play an important physiological role in neuronal cells.