Functional equivalency of B7-1 and B7-2 for costimulating plasmid DNA vaccine-elicited CTL responses

A costimulatory signal in addition to an Ag-specific stimulus is required for optimal activation of T lymphocytes. CD28, the primary positive costimulatory receptor on T cells, has two identified ligands, B7-1 and B7-2. Whether B7-1 and B7-2 have identical, overlapping, or distinct functions remains unresolved. In this study, we show that mice lacking B7-2 were unable to generate CTL responses following immunization with a plasmid DNA vaccine. The ability of these B7-2-deficient mice to generate CTL responses following plasmid gp120 DNA vaccination was fully reconstituted by coadministering either a plasmid expressing B7-2 or B7-1. Moreover, the ability to generate CTL responses following plasmid DNA vaccination in mice lacking both B7-1 and B7-2 could be reconstituted by administering either plasmid B7-1 or plasmid B7-2 with the vaccine construct. These data demonstrate that either B7-1 or B7-2 administered concurrently with a plasmid DNA vaccine can fully costimulate vaccine-elicited CTL responses. Functional differences between B7-1 and B7-2 observed in vivo therefore may not reflect inherent differences in the interactions of CD28 with these ligands.     

Interleukin-7 mediates the generation and expansion of murine allosensitized and antitumor CTL.

Interleukin-7 (IL-7) is a 25-kDa cytokine that was initially described as a pre-B cell growth factor and more recently has been shown to cause T cell proliferation. We have investigated the in vitro effects of IL-7 on mature T cells to include the generation and further expansion of allospecific and antitumor CTL. B6 anti-DBA allospecific CTL were generated in the presence of IL-7, IL-2, the combination IL-7 plus IL-2, or no cytokine. IL-7 alone or when combined with IL-2 enhanced the generation of allospecific CTL. To evaluate the proliferative effects of IL-7, 4-day B6 anti-DBA cultures were cultured in IL-7, IL-2, or no cytokine. Cell proliferation and duration of growth of cells cultured in IL-7 were significantly greater than cells cultured in IL-2 or in the absence of cytokine. Allospecific cytolytic activity was maintained during proliferation in IL-7 to a maximum of 60 days. In contrast with the ability of IL-2 to generate LAK cells, murine splenocytes cultured at varying doses of IL-7 (1 to 10,000 ng/ml), resulted in minimal LAK cell activity. The effect of IL-7 in the generation of CTL with antitumor activity was also studied. Seven days after footpad injection of MCA 203 or 205 sarcoma, draining lymph nodes (DLN) were harvested and restimulated in vitro with MCA 203 or 205, respectively, and maintained in culture with either IL-7, IL-2, the combination of IL-7 plus IL-2, or no cytokine. After 10 days in culture, cells generated in IL-7 or IL-2 exhibited similar cytotoxicity against the syngeneic autologous MCA tumor. IL-7 generated cells, however, showed specificity when tested by 51Cr release which was not seen with IL-2-generated cells. Cells generated in IL-7 plus IL-2 were more cytolytic than cells cultured with either cytokine alone. To further define the mechanism of action of IL-7 in antitumor CTL cultures, a monoclonal antibody, S4B6.1, capable of blocking murine-specific IL-2 was employed. The partial inhibition by this mAb of the generation of antitumor CTL demonstrated that IL-7 acted, in part, by an IL-2-dependent mechanism. Finally, IL-7 cultures restimulated at Day 11 with autologous MCA 203 showed greater proliferation than IL-2 cultures and remained lytic at Day 21 of culture.(ABSTRACT TRUNCATED AT 400 WORDS)     

ATP-induced apoptosis of thymocytes is mediated by activation of P2 X 7 receptor and involves de novo ceramide synthesis and mitochondria

Thymocytes were reported to undergo apoptosis in the presence of extracellular ATP through the activation of the purinergic receptors P2 X 1R, P2 X 7R or both. We investigated the identity of the P2 X R and the signaling pathways involved in ATP-mediated apoptosis. Apoptosis elicited by ATP was prevented by inhibition of P2 X 7R, or in thymocytes bearing a mutated P2 X 7R, and reproduced with a P2 X 7R agonist, but not with a P2 X 1R agonist. Stimulation of thymocytes with either ATP or a P2 X 7R agonist was found to stimulate a late de novo ceramide synthesis and mitochondrial alterations. Inhibition of either processes attenuated apoptosis. Interestingly, stimulation with either ATP or a P2 X 1R agonist induced an early ceramide accumulation and a weak caspases-3/7 activation that did not lead to apoptosis. In conclusion, de novo ceramide generation and mitochondrial alterations, both resulting from P2 X 7R activation, were implicated in ATP-induced thymocyte apoptosis.     

Synthesis of new nucleoside analogues comprising a geminal difluorocyclopropane moiety as potential antiviral/antitumor agents

Geminal difluorocyclopropane analogues of nucleosides 7a-7e were synthesized. Compounds 7a and 7c-7e were obtained by alkylation of nucleic acid bases or their appropriate precursors with (cis)-1-benzyloxymethyl-2-bromomethyl-3,3-difluorocyclopropane+ ++ (8). Analogue 7b was prepared by hydrolysis of 2-amino-6-chloropurine derivative 7e. Compounds 7a-7d did not exhibit any antiviral activity against HCMV, HSV-1, HSV-2, EBV, VZV, HBV and HIV-1 or antitumor effects against murine leukemia L1210, mouse tumors PO3 or C38 and human tumor H15.     

Coexpression of the human HLA-A2 or HLA-B7 heavy chain gene and human beta 2-microglobulin gene in L cells

L cells expressing human HLA-A2 or HLA-B7 class I antigen heavy chains are not recognized by human cytotoxic T lymphocytes directed at HLA-A2 or HLA-B7 antigens. To test whether the absence of human beta 2-m was the cause of the lack of recognition by the human cytotoxic T lymphocytes, coexpression of the human beta 2-m gene and the HLA-A2 or HLA-B7 heavy chain in L cells ("double transfectants") was obtained. In addition, L cells expressing HLA-A2 or HLA-B7 antigens in association with human beta 2-m were obtained by an exchange reaction, in which human beta 2-m from serum replaced the endogenous murine beta 2-m. Both types of transfectant cells were used in 51Cr-release assays and cold target inhibition assays for human cytotoxic T cell clones which were directed at HLA-A2 or HLA-B7. Neither human CTL clones nor a mixture of CTL specific for HLA-A2 and HLA-B7 were able to recognize these cells. Several alternative explanations for these observations are discussed.     

The Second Transmembrane Domain of P2X7 Contributes to Dilated Pore Formation

Activation of the purinergic receptor P2X7 leads to the cellular permeability of low molecular weight cations. To determine which domains of P2X7 are necessary for this permeability, we exchanged either the C-terminus or portions of the second transmembrane domain (TM2) with those in P2X1 or P2X4. Replacement of the C-terminus of P2X7 with either P2X1 or P2X4 prevented surface expression of the chimeric receptor. Similarly, chimeric P2X7 containing TM2 from P2X1 or P2X4 had reduced surface expression and no permeability to cationic dyes. Exchanging the N-terminal 10 residues or C-terminal 14 residues of the P2X7 TM2 with the corresponding region of P2X1 TM2 partially restored surface expression and limited pore permeability. To further probe TM2 structure, we replaced single residues in P2X7 TM2 with those in P2X1 or P2X4. We identified multiple substitutions that drastically changed pore permeability without altering surface expression. Three substitutions (Q332P, Y336T, and Y343L) individually reduced pore formation as indicated by decreased dye uptake and also reduced membrane blebbing in response to ATP exposure. Three others substitutions, V335T, S342G, and S342A each enhanced dye uptake, membrane blebbing and cell death. Our results demonstrate a critical role for the TM2 domain of P2X7 in receptor function, and provide a structural basis for differences between purinergic receptors.     

Sugar-modified derivatives of cytostatic 7-(het)aryl-7-deazaadenosines: 2'-C-methylribonucleosides, 2'-deoxy-2'-fluoroarabinonucleosides, arabinonucleosides and 2'-deoxyribonucleosides

A series of novel sugar-modified derivatives of cytostatic 7-hetaryl-7-deazaadenosines (2'-C-methylribonucleosides, 2'-deoxy-2'-fluoroarabinonucleosides, arabinonucleosides and 2'-deoxyribonucleosides) was prepared and screened for biological activity. The synthesis consisted of preparation of the corresponding sugar-modified 7-iodo-7-deazaadenine nucleosides and their aqueous-phase Suzuki-Miyaura cross-coupling reactions with (het)arylboronic acids or Stille couplings with hetarylstannanes in DMF. The synthesis of 7-iodo-7-deazaadenine nucleosides was based on a glycosidation of 6-chloro-7-iodo-7-deazapurine with a suitable sugar synthon or on an interconversion of 2'-OH stereocenter (for arabinonucleosides). Several examples of 2'-C-Me-ribonucleosides showed moderate anti-HCV activities in a replicon assay accompanied by cytotoxicity. Several 7-hetaryl-7-deazaadenine fluoroarabino- and arabinonucleosides exerted moderate micromolar cytostatic effects. The most active was 7-ethynyl-7-deazaadenine fluoroarabinonucleoside which showed submicromolar antiproliferative activity. However, all the sugar-modified derivatives were less active than the parent ribonucleosides.     

P2X7 nucleotide receptors mediate blebbing in osteoblasts through a pathway involving lysophosphatidic acid

Extracellular nucleotides, released in response to mechanical or inflammatory stimuli, signal through P2 receptors in many cell types, including osteoblasts. P2X7 receptors are ATP-gated cation channels that can induce formation of large membrane pores. Disruption of the gene encoding the P2X7 receptor leads to decreased periosteal bone formation and insensitivity of the skeleton to mechanical stimulation. Our purpose was to investigate signaling pathways coupled to P2X7 activation in osteoblasts. Live cell imaging showed that ATP or 2 ',3 '-O-(4-benzoylbenzoyl)-ATP (BzATP), but not UTP, UDP, or 2-methylthio-ADP, induced dynamic membrane blebbing in calvarial osteoblasts. Blebbing was observed in calvarial cells from wildtype but not P2X7 knock-out mice. P2X7 receptors coupled to activation of phospholipase D and A2, inhibition of which suppressed BzATP-induced blebbing. Activation of these phospholipases leads to production of lysophosphatidic acid (LPA). LPA caused dynamic blebbing in osteoblasts from both wild-type and P2X7 knock-out mice, similar to that induced by BzATP in wildtype cells. However, LPA-induced blebbing was more rapid in onset and was not affected by inhibition of phospholipase D or A2. Blockade or desensitization of LPA receptors suppressed blebbing in response to LPA and BzATP, without affecting P2X7-stimulated pore formation. Thus, LPA functions downstream of P2X7 receptors to induce membrane blebbing. Furthermore, inhibition of Rho-associated kinase abolished blebbing induced by both BzATP and LPA. In summary, we propose a novel signaling axis that links P2X7 receptors through phospholipases to production of LPA and activation of Rho-associated kinase. This pathway may contribute to P2X7-stimulated osteogenesis during skeletal development and mechanotransduction.     

The RHO1-GAPs SAC7, BEM2 and BAG7 control distinct RHO1 functions in Saccharomyces cerevisiae

In Saccharomyces cerevisiae, the small GTPase RHO1 plays an essential role in the control of cell wall synthesis and organization of the actin cytoskeleton. Several regulators for RHO1 are known, including the GTPase-activating proteins (GAPs) SAC7 and BEM2. Here we show that BAG7, identified as the closest homologue of SAC7, also acts as a GAP for RHO1 in vitro and in vivo. Furthermore, we find that BAG7, SAC7, and BEM2 are functionally different in vivo. Overexpression of BAG7 or SAC7,but not BEM2, suppresses the cold sensitivity of a sac7 mutation and the lethality of RHO1 hyperactivation in response to cell wall damage. In contrast, overexpression of BEM2 or SAC7, but not BAG7, downregulates the RHO1-controlled PKC1-MPK1 pathway, and disruption of BEM2 or SAC7, but not BAG7, results in increased MPK1 activation. We conclude that BEM2 and SAC7, but not BAG7, are involved in the control of the RHO1-mediated activation of MPK1, whereas BAG7 and SAC7, but not BEM2, are involved in the regulation of other RHO1 functions. This suggests that different RHO1GAPs control different RHO1 effector pathways, thus ensuring their individual regulation at the appropriate place and time.     

B7 costimulation is critical for antibody class switching and CD8(+) cytotoxic T-lymphocyte generation in the host response to vesicular stomatitis virus

Antibody and cytotoxic T-lymphocyte (CTL) responses have critical roles in eliminating many viral infections. In addition to stimulation of the T-cell receptor, T cells require costimulatory signals to respond optimally. We evaluated the role of B7 costimulatory molecules (B7-1 and B7-2) in the immune response to viral infection using vesicular stomatitis virus (VSV) and mice lacking either B7-1 or B7-2 or both molecules. Mice lacking both B7-1 and B7-2 had essentially no anti-VSV immunoglobulin G1 (IgG1) response, decreased IgG2a responses, and normal IgM responses, while mice lacking either B7-1 or B7-2 had unaltered anti-VSV antibody responses compared to wild-type mice. Depletion of CD4(+) cells further reduced the IgG2a response in mice lacking both B7 molecules, suggesting that CD4(-) cells may supply help for IgG2a in the absence of B7 costimulation. The absence of both B7 molecules profoundly reduced generation of both primary and secondary VSV-specific class I major histocompatibility complex (MHC)-restricted CTL, whereas VSV-specific CTL responses in mice lacking either B7-1 or B7-2 were similar to those of wild-type animals. Class I MHC-restricted CTL in wild-type mice were not dependent on CD4(+) cells, suggesting that the failure of CTL in the absence of B7s is due to a lack of B7 costimulation directly to the CD8(+) CTL. These data demonstrate that B7-1 and B7-2 have critical, overlapping functions in the antibody and CTL responses to this viral infection.     

Expression and contribution of B7-1 (CD80) and B7-2 (CD86) in the early immune response to Leishmania major infection.

CD28 interactions promote T cell responses, and whether B7-1 or B7-2 is utilized may influence Th cell subset development. CD28 blockade by CTLA-4Ig treatment or by targeted gene disruption has yielded different conclusions regarding the role of CD28 in the development of Th1 and Th2 cells following Leishmania major infection. In this study, we demonstrate that B7-mediated costimulation is required for the development of the early immune response following infection of resistant or susceptible mice. In contrast, CD28-/- BALB/c mice infected with L. major produce cytokines comparable to those of infected wild-type mice. Treatment of CD28-/- mice with CTLA-4Ig did not diminish this response, suggesting that a B7-independent pathway(s) contributes to the early immune response in these mice. In conventional BALB/c or C3H mice, B7-2 functions as the dominant costimulatory molecule in the initiation of early T cell activation following L. major infection, leading to IL-4 or IFN-gamma production, respectively. The preferential interaction of B7-2 with its ligand(s) in the induction of these responses correlates with its constitutive expression relative to that of B7-1. However, B7-1 can equally mediate costimulation for the production of either IL-4 or IFN-gamma when expressed at high levels. Thus, in leishmaniasis, costimulation involving B7-1 or B7-2 can result in the production of either Th1 or Th2 cytokines, rather than a preferential induction of one type of response.     

P2X(7) receptor and polykarion formation

Cell fusion is a central phenomenon during the immune response that leads to formation of large elements called multinucleated giant cells (MGCs) of common occurrence at sites of granulomatous inflammation. We have previously reported on the involvement in this event of a novel receptor expressed to high level by mononuclear phagocytes, the purinergic P2X(7) receptor. Herein, we show that blockade of this receptor by a specific monoclonal antibody prevents fusion in vitro. In contrast, cell fusion is stimulated by addition of enzymes that destroy extracellular ATP (i.e., apyrase or hexokinase). Experiments performed with phagocytes selected for high (P2X(7) hyper) or low (P2X(7) hypo) P2X(7) expression show that fusion only occurs between P2X(7) hyper/P2X(7) hyper and not between P2X(7) hyper/P2X(7) hypo or P2X(7) hypo/P2X(7) hypo. During MGCs formation we detected activation of caspase 3, an enzyme that is powerfully stimulated by P2X(7). Finally, we observed that during MGCs formation, the P2X(7) receptor is preferentially localized at sites of cell-to-cell contact. These findings support the hypothesis originally put forward by our group that the P2X(7) receptor participates in multinucleated giant cell formation.     

Expression of the major histocompatibility antigens HLA-A2 and HLA-B7 by DNA-mediated gene transfer

Genes coding for the heavy chain of the class I antigens HLA-A2 or HLA-B7 of the human major histocompatibility complex have been introduced into mouse LtK- cells by cotransfection with the herpes simplex virus thymidine kinase gene. HAT-resistant colonies were isolated expressing either HLA-A2 or HLA-B7 as monitored by indirect immunofluorescence. Immunoprecipitation analysis of both antigens by either sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) or isoelectric focusing (IEF) showed that they were identical to the HLA-A2 and HLA-B7 expressed in the human lymphoblastoid cell line JY (homozygous HLA-A2, HLA-B7). However, human cytotoxic T lymphocytes (CTL) generated against JY and CTL clones specific for HLA-A2 or HLA-B7 were unable to recognize the transfectants as targets. These results indicate that the human HLA-A2 (or B7) complexed with the murine beta 2-microglobulin could be an inappropriate target structure for the CTL. However, because the transfectants are not killed by human CTL even in the presence of lectins, it is suggested that other molecules that are not able to overcome the human-mouse species barrier may be involved in the killing mechanism.     

Autoantibody responses and pathology regulated by B7-1 and B7-2 costimulation in MRL/lpr lupus

The activation of T lymphocytes requires both Ag-mediated signaling through the TCR as well as costimulatory signals transmitted through B7-1 and/or B7-2 with CD28. The interference of B7-mediated costimulatory signals has been proposed as one immunotherapeutic intervention for the prevention autoimmune disease. This study has examined autoantibody responses and autoimmune pathology in a murine model of human systemic lupus erythematosus (SLE), the MRL-lpr/lpr mouse, genetically deficient in B7-1 or B7-2, or in mice treated with B7-1/B7-2 blocking Abs. In contrast to other studies of murine models of SLE, MRL-lpr/lpr mice treated with B7 blocking Abs exhibit strong anti-small nuclear ribonucleoprotein (snRNP) and anti-DNA autoantibody responses with some changes in isotype switching as compared with untreated animals. All MRL-lpr/lpr mice deficient in B7-1 or B7-2 produce anti-snRNP and anti-DNA titers with isotypes virtually identical with wild-type animals. However, the absence of B7-2 costimulation did interfere with the spontaneous activation and the accumulation of memory CD4+ or CD8+ T lymphocytes characteristic of wild-type MRL-lpr/lpr mice. IgG and C3 complement deposition was less pronounced in the kidneys of B7-2 deficient MRL-lpr/lpr mice, reflecting their lessor degree of glomerulonephritis. By comparison, B7-1-deficient MRL-lpr/lpr mice had more severe IgG and C3 deposits in glomeruli.     

A novel conserved isoform of the ubiquitin ligase UFD2a/UBE4B is expressed exclusively in mature striated muscle cells

Yeast Ufd2p was the first identified E4 multiubiquitin chain assembly factor. Its vertebrate homologues later referred to as UFD2a, UBE4B or E4B were also shown to have E3 ubiquitin ligase activity. UFD2a function in the brain has been well established in vivo, and in vitro studies have shown that its activity is essential for proper condensation and segregation of chromosomes during mitosis. Here we show that 2 alternative splice forms of UFD2a, UFD2a-7 and -7/7a, are expressed sequentially during myoblast differentiation of C2C12 cell cultures and during cardiotoxin-induced regeneration of skeletal muscle in mice. UFD2a-7 contains an alternate exon 7, and UFD2a-7/7a, the larger of the 2 isoforms, contains an additional novel exon 7a. Analysis of protein or mRNA expression in mice and zebrafish revealed that a similar pattern of isoform switching occurs during developmental myogenesis of cardiac and skeletal muscle. In vertebrates (humans, rodents, zebrafish), UFD2a-7/7a is expressed only in mature striated muscle. This unique tissue specificity is further validated by the conserved presence of 2 muscle-specific splicing regulatory motifs located in the 3' introns of exons 7 and 7a. UFD2a interacts with VCP/p97, an AAA-type ATPase implicated in processes whose functions appear to be regulated, in part, through their interaction with one or more of 15 previously identified cofactors. UFD2a-7/7a did not interact with VCP/p97 in yeast 2-hybrid experiments, which may allow the ATPase to bind cofactors that facilitate its muscle-specific functions. We conclude that the regulated expression of these UFD2a isoforms most likely imparts divergent functions that are important for myogenisis.     

4-1BBL cooperates with B7-1 and B7-2 in converting a B cell lymphoma cell line into a long-lasting antitumor vaccine

A20 is a B cell lymphoma that constitutively expresses the costimulatory molecule B7-2 yet grows readily as a tumor in syngeneic BALB/c mice. We have compared the tumorigenicity of A20 variants expressing either B7-1 (A20/B7-1) or B7-2 (A20/B7-2) with an A20 variant expressing B7-1 and B7-2 with 4-1BBL (A20/4-1BBL), a costimulatory member of the TNF family. Mice injected with tumors expressing the vector backbone (A20/CMV) or B7-1 developed tumors within 25 days of s.c. injection. In contrast, mice injected with A20/4-1BBL were tumor free for the 150-day follow-up period, while 25% of mice injected with A20/B7-2 developed tumors. Tumorigenicity experiments using nude mice indicated the requirement for T cells for variant rejection. Almost all mice that resisted the initial tumor challenge were resistant to further challenge with the parental tumor. Splenocytes from these mice showed high CTL lytic activity against the parental tumor, A20, as well as the syngeneic BALB/c lymphoma K46J, but showed background levels of lytic activity against the congenic SCID thymoma line ST-D2 or the allogeneic EL4 thymoma. In vitro blocking experiments with anti-B7-1 plus anti-B7-2 and/or soluble 4-1BB receptor showed B7-1, B7-2, and 4-1BBL all contributed to the CTL activity. Thus, the data show that neither B7-1 or B7-2 alone can confer full immunogenicity to the A20 lymphoma but that the addition of 4-1BBL results in a tumor that is highly immunogenic and can confer long-lasting protection against challenge with parental tumor in vivo.     

Interaction of Drosophila melanogaster prohormone convertase 2 and 7B2. Insect cell-specific processing and secretion

The prohormone convertases (PCs) are an evolutionarily ancient group of proteases required for the maturation of neuropeptide and peptide hormone precursors. In Drosophila melanogaster, the homolog of prohormone convertase 2, dPC2 (amontillado), is required for normal hatching behavior, and immunoblotting data indicate that flies express 80- and 75-kDa forms of this protein. Because mouse PC2 (mPC2) requires 7B2, a helper protein for productive maturation, we searched the fly data base for the 7B2 signature motif PPNPCP and identified an expressed sequence tag clone encoding the entire open reading frame for this protein. dPC2 and d7B2 cDNAs were subcloned into expression vectors for transfection into HEK-293 cells; mPC2 and rat 7B2 were used as controls. Although active mPC2 was detected in medium in the presence of either d7B2 or r7B2, dPC2 showed no proteolytic activity upon coexpression of either d7B2 or r7B2. Labeling experiments showed that dPC2 was synthesized but not secreted from HEK-293 cells. However, when dPC2 and either d7B2 or r7B2 were coexpressed in Drosophila S2 cells, abundant immunoreactive dPC2 was secreted into the medium, coincident with the appearance of PC2 activity. Expression and secretion of dPC2 enzyme activity thus appears to require insect cell-specific posttranslational processing events. The significant differences in the cell biology of the insect and mammalian enzymes, with 7B2 absolutely required for secretion of dPC2 and zymogen conversion occurring intracellularly in the case of dPC2 but not mPC2, support the idea that the Drosophila enzyme has specific requirements for maturation and secretion that can be met only in insect cells.     

Pyrrolo[2,3-d]pyrimidine nucleosides: synthesis and antitumor activity of 7-substituted 7-deaza-2'-deoxyadenosines

A one step synthesis, using the nucleoside 7-iodo-2'-deoxytubercidin (2b) in a Pd(0)/Cu(I)-catalyzed cross coupling reaction furnished a series of 7-alkynyl-2'-deoxytubercidin derivatives. The 7-iodo-, 7-chloro- or 7-bromo 2'-deoxytubercidins 2b-d as well as certain 7-alkynyl derivatives show significant activity against several tumor cell lines, with 7-iodo-2'-deoxytubercidin (2b) as the most effective compound.     

Synthesis of "reversed" methylenecyclopropane analogues of antiviral phosphonates

Synthesis of "reversed" methylenecyclopropane analogues of nucleoside phosphonates 6a,7a, 6b, and 7b is described. 1-Bromo-1-bromomethylcyclopropane 8 was converted to the bromocyclopropyl phosphonate 9 by Michaelis-Arbuzov reaction with triisopropyl phosphite. Base-catalyzed beta-elimination and deacetylation gave the key Z- and E-hydroxymethylcyclopropyl phosphonates 10 and 11 separated by chromatography. The Mitsunobu type of alkylation of 10 or 11 with adenine or 2-amino-6-chloropurine afforded phosphonates 12a, 12b, 13a, and 13b. Acid hydrolysis furnished the adenine and guanine analogues 6a, 7a, 6b, and 7b. The E and Z configuration was assigned on the basis of NOE experiments with phosphonates 6b and 7b. All Z- and E-isomers were also distinguished by different chemical shifts of CH2O or CH2N (H4 or H4'). Significant differences of the chemical shifts of the cyclopropane C3(3') carbons and coupling constants 3JP,C2(2') or 3JP,C3(3') selective for the Z- or E-isomers were also noted. Phosphonates 6a, 7a, 6b, and 7b are devoid of significant antiviral activity.