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		Research T cell independent secondary antibody responses to the envelope protein of simian immunodeficiency virus Ghulam Nabi, Vladimir Temchura, Claudius Großmann, Seraphin Kuate, Matthias Tenbusch, Klaus Überla Retrovirology 2012, 9:42 (14 May 2012) Abstract \| Provisional PDF \| Editor’s summary Membrane-bound trimeric Env seems to be responsible for the maintenance of high levels of anti-Env antibodies during progression to AIDS. This T cell independent secondary antibody response may prevent T cell-dependent affinity maturation and thus contribute to viral immune escape by favoring persistence of non-protective antibodies.
		Research The prototype foamy virus protease is active independently of the integrase domain Ralf Spannaus, Maximilian J. Hartl, Birgitta M. Wöhrl, Axel Rethwilm, Jochen Bodem Retrovirology 2012, 9:41 (10 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This paper shows that the FV integrase is required for Pol encapsidation and that the FV PR activity is integrase independent. The study shows that an active PR can be encapsidated in trans as a GagPR-RT fusion protein.
		Research Limited SHIV env diversification in macaques failing oral antiretroviral pre-exposure prophylaxis Qi Zheng, Susan Ruone, William M Switzer, Walid Heneine, J Gerardo García-Lerma Retrovirology 2012, 9:40 (9 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary Infection during pre-exposure prophylaxis (PrEP) limits early virus evolution likely because of a direct antiviral effect of PrEP and/or reduced target cell availability. Reduced virus diversification during early infection might enhance immune control by slowing the selection of escape mutants
		Review HLA-C and HIV-1: Friends or Foes? Donato Zipeto, Alberto Beretta Retrovirology 2012, 9:39 (9 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This review highlights the role of HLA-C in association with HIV-1 viral load, but also addresses the contradiction of the association between high cell surface expression of an inhibitory molecule and strong cell-mediated immunity. To explore additional mechanisms of control of HIV-1 replication by HLA-C, this review addresses specific features of the molecule, like its tendency to be expressed as open conformer upon cell activation, which endows it with a unique capacity to associate with other cell surface molecules as well as with HIV-1 proteins.
		Research HIV-1-encoded antisense RNA suppresses viral replication for a prolonged period Mie Kobayashi-Ishihara, Makoto Yamagishi, Takuma Hara, Yuka Matsuda, Ryutaro Takahashi, Ariko Miyake, Kazumi Nakano, Tadanori Yamochi, Takaomi Ishida, Toshiki Watanabe Retrovirology 2012, 9:38 (8 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary The present study identified an accurate structure of the major form of antisense RNAs expressed from the HIV-1NL4-3 provirus and demonstrated a new role of the antisense RNA in viral replication, suggesting a novel viral mechanism that regulates self-limited replication of HIV-1.
		Research Protein kinase C-delta regulates HIV-1 replication at an early post-entry step in macrophages Xavier Contreras, Olfa Mzoughi, Fabrice Gaston, B Matija Peterlin, Elmostafa Bahraoui Retrovirology 2012, 9:37 (3 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This study identified PKC-delta as a major cellular cofactor for HIV-1 replication in macrophages. PKC-delta was stimulated following the interaction between the virus and its target cell. Inhibition of PKC-delta blocked the replication of R5-tropic viruses in primary human macrophages.
		Research MiniCD4 protein resistance mutations affect binding to the HIV-1 gp120 CD4 binding site and decrease entry efficiency Katrijn Grupping, Philippe Selhorst, Johan Michiels, Katleen Vereecken, Leo Heyndrickx, Pascal Kessler, Guido Vanham, Loïc Martin, Kevin K Ariën Retrovirology 2012, 9:36 (2 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary The present study reports on the resistance induction of two subtype B HIV-1 against the most active miniCD4, M48U1, and its ancestor, M48, and how these mutated positions affect CD4bs recognition, entry efficiency, and sensitivity to other CD4bs inhibitors. Resistance against M48U1 was always associated with S375R/N substitution in both BaL and SF162; M48 resistance was associated with D474N substitution in SF162 and with H105Y substitution in BaL.
		Review Emerging complexities of APOBEC3G action on immunity and viral fitness during HIV infection and treatment Mahdis Monajemi, Claire F Woodworth, Jessica Benkaroun, Michael Grant, Mani Larijani Retrovirology 2012, 9:35 (30 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary Despite its effectiveness in various experimental systems, numerous recent studies have shown that the ability of A3G to combat HIV in the physiological setting is severely limited. In fact, it has become apparent that A3G's mutational activity may actually enhance viral fitness by accelerating HIV evolution towards the evasion of both anti-viral drugs and the immune system. Here the authors present an overview of recent data that bring to light historical overestimation of A3G's standing as a strictly anti-viral agent.
		Research Identification of a highly conserved valine-glycine-phenylalanine amino acid triplet required for HIV-1 Nef function Pieter J Meuwissen, Bettina Stolp, Veronica Iannucci, Jolien Vermeire, Evelien Naessens, Kalle Saksela, Matthias Geyer, Guido Vanham, Kevin K Arien, Oliver T Fackler, Bruno Verhasselt Retrovirology 2012, 9:34 (27 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This study describes a highly conserved three amino acid VGF motif that together with the acidic cluster and the proline-rich motif form a previously unrecognized amphipathic surface on Nef. This surface appears to be essential for the majority of Nef functions and thus represents a prime target for the pharmacological inhibition of Nef.
		Research Proteomic analysis of HIV-1 Nef cellular binding partners reveals a role for exocyst complex proteins in mediating enhancement of intercellular nanotube formation Joya Mukerji, Kevin C Olivieri, Vikas Misra, Kristin A Agopian, Dana Gabuzda Retrovirology 2012, 9:33 (25 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary To identify Nef binding partners involved in Pak2-association dependent Nef functions, the authors employed tandem mass spectrometry analysis of Nef immunocomplexes from Jurkat cells expressing wild-type Nef or Nef mutants defective for the ability to associate with Pak2 (F85L, F89H, H191F and A72P, A74P in NL4-3). They report that wild-type, but not mutant Nef, was associated with 5 components of the exocyst complex (EXOC1, EXOC2, EXOC3, EXOC4, and EXOC6), an octameric complex that tethers vesicles at the plasma membrane, regulates polarized exocytosis, and recruits membranes and proteins required for nanotube formation.
		Research Vpx is Critical for SIVmne infection of pigtail macaques Michael Belshan, Jason T Kimata, Charles Brown, Xiaogang Cheng, Anna McCulley, Alison Larsen, Rajesh Thippeshappa, Vida Hodara, Luis Giavedoni, Vanessa Hirsch, Lee Ratner Retrovirology 2012, 9:32 (24 April 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary This work demonstrates that the activities of Vpx to overcome restrictions in culture in vitro are also likely to be important for establishment of infection in vivo and suggest that both the nuclear localization and DCAF1-interaction functions of Vpx are critical in vivo
		Research Stable multi-infection of splenocytes during SIV infection - the basis for continuous recombination Anke Schultz, Sieghart Sopper, Ulrike Sauermann, Andreas Meyerhans, Rodolphe Suspene Retrovirology 2012, 9:31 (23 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary SIV multi-infection of single splenocytes was readily detected in all monkeys and all stages of the infection. Single-infected cells were more frequent than double or triple infected cells. There was no strong trend linking the copy number distribution to plasma viral load, disease stage or CD4 cell counts.
		Research Second-site suppressors of HIV-1 capsid mutations: restoration of intracellular activities without correction of intrinsic capsid stability defects Ruifeng Yang, Jiong Shi, In-Ja L Byeon, Jinwoo Ahn, Jonathan H Sheehan, Jens Meiler, Angela M Gronenborn, Christopher Aiken Retrovirology 2012, 9:30 (19 April 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary The second-site suppressor mutations in CA identified here rescue virus infection without correcting the intrinsic capsid stability defects associated with the P38A and E45A mutations. The suppressors also restored wild type virus function in several cell-based assays. Thus, while proper HIV-1 uncoating in target cells is dependent on the intrinsic stability of the viral capsid, the effects of stability-altering mutations can be mitigated by additional mutations that affect interactions with host factors in target cells or the consequences of these interactions.
		Research Modulation of HIV-1 Gag NC/p1 cleavage efficiency affects protease inhibitor resistance and viral replicative capacity Noortje M van Maarseveen, Dan Andersson, Martin Lepšík, Axel Fun, Pauline J Schipper, Dorien de Jong, Charles AB Boucher, Monique Nijhuis Retrovirology 2012, 9:29 (1 April 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary The authors show that single NC/p1 mutants, which displayed only a slight increase in protease inhibitor (PI) resistance didn't show an obvious change in replicative capacity (RC), but that double NC/p1 mutant which displayed a clear increase in processing efficiency and PI resistance did have a clear reduction in RC.
		Research New STLV-3 strains and a divergent SIVmus strain identified in non-human primate bushmeat in Gabon Florian Liegeois, Vanina Boue, Fatima Mouacha, Christelle Butel, Bertrand Mve-Ondo, Xavier Pourrut, Eric Leroy, Martine Peeters, Francois Rouet Retrovirology 2012, 9:28 (30 March 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary SIV and STLV antibodies were detected by HIV and HTLV antigens and PCRs were performed on samples with an HIV or/and HTLV-like or indeterminate profile. Fourteen percent of the samples cross-reacted with HIV antigens and 44% with HTLV antigens. The authors report STLV-1 infections in five of the seven species tested. STLV3 infections, including a new STLV 3 subtype, STLV-1 and 3 co-infections and triple SIV, STLV-1, STLV-3 infections.
		Research Tailored enrichment strategy detects low abundant small noncoding RNAs in HIV-1 infected cells Claudia F Althaus, Valentina Vongrad, Barbara Niederöst, Beda Joos, Francesca Di Giallonardo, Philip Rieder, Jovan Pavlovic, Alexandra Trkola, Huldrych F Günthard, Karin J Metzner, Marek Fischer Retrovirology 2012, 9:27 (29 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary 892 individual HIV-1 sncRNAs were cloned and sequenced from nine different sncRNA libraries derived from five independent experiments. They are spread throughout the HIV-1 genome, however, forming certain clusters, and almost 10% show an antisense orientation. The results show that HIV-1 infected cells generate virally encoded sncRNAs, which might play a role in the HIV-1 life cycle.
		Research Host-pathogen interactome mapping for HTLV-1 and -2 retroviruses Nicolas Simonis, Jean-François Rual, Irma Lemmens, Mathieu Boxus, Tomoko Hirozane-Kishikawa, Jean-Stéphane Gatot, Amélie Dricot, Tong Hao, Didier Vertommen, Sébastien Legros, Sarah Daakour, Niels Klitgord, Maud Martin, Jean-François Willaert, Franck Dequiedt, Vincent Navratil, Michael E Cusick, Arsène Burny, Carine Van Lint, David E Hill, Jan Tavernier, Richard Kettmann, Marc Vidal, Jean-Claude Twizere Retrovirology 2012, 9:26 (29 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary This work employed a scalable methodology for the systematic mapping and comparison of pathogen-host protein interactions that includes stringent yeast two-hybrid screening and systematic retest, as well as two independent validations through an additional protein interaction detection method and a functional transactivation assay. The authors found 166 interactions between 10 viral proteins and 122 human proteins.
		Viewpoints Viewpoint on Emv2, the onlhy endogenous ecotropic murine leukemia virus of C57BL/6 mice Christine A Kozak Retrovirology 2012, 9:25 (22 March 2012) Abstract \| Full text \| PDF \| PubMed \| 2 comments \| Editor’s summary Kozak comments on the discussion between Young et al. and Lee and Cho.
		Correspondence Reply to Emv2, the only endogenous ecotropic murine leukemia virus of C57BL/6J mice Kang-Hoon Lee, Kiho Cho Retrovirology 2012, 9:24 (22 March 2012) Abstract \| Full text \| PDF \| PubMed \| Cited on BioMed Central \| Editor’s summary Lee and Cho reply to the correspondence by Young et al.
		Correspondence Emv2, the only endogenous ecotropic murine leukemia virus of C57BL/6J mice George R Young, George Kassiotis, Jonathan P Stoye Retrovirology 2012, 9:23 (22 March 2012) Abstract \| Full text \| PDF \| PubMed \| Cited on BioMed Central \| Editor’s summary The authors suggest that due diligence has not been applied in a recent description by Cho et al. of an endogenous ecotropic retrovirus that was published in Retrovirology.
		Research Timing and source of subtype-C HIV-1 superinfection in the newly infected partner of Zambian couples with disparate viruses Colleen S Kraft, Debby Basu, Paulina A Hawkins, Peter T Hraber, Elwyn Chomba, Joseph Mulenga, William Kilembe, Naw H Khu, Cynthia A Derdeyn, Susan A Allen, Olivier Manigart, Eric Hunter Retrovirology 2012, 9:22 (20 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary In this subtype-C discordant couple cohort, superinfection, during the first year after HIV-1 infection of the previously negative partner, occurred at a rate similar to primary infection (13.6% [95% CI 5.2-34.8] vs 7.8% [7.1-8.6]). While limited intra-couple superinfection may in part reflect continued condom usage within couples, this and our lack of detecting newly superinfected individuals after one year of primary infection raises the possibility that immunological resistance to intra-subtype superinfection may develop over time in subtype C infected individuals.
		Research The endogenous retrovirus ENS-1 provides active binding sites for transcription factors in embryonic stem cells that specify extra embryonic tissue Anne Mey, Herve Acloque, Emmanuelle Lerat, Sebastien Gounel, Violaine Tribollet, Sophie Blanc, Damien Curton, Anne-Marie Birot, M Angela Nieto, Jacques Samarut Retrovirology 2012, 9:21 (15 March 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary The authors show that Ens-1 LTR activity is controlled by two transcriptional pathways that drive pluripotent cells to alternative developmental fates.
		Research Independent evolution of macrophage-tropism and increased charge between HIV-1 R5 envelopes present in brain and immune tissue Maria P Gonzalez-Perez, Olivia J O'Connell, Rongheng Lin, William M Sullivan, Jeanne Bell, Peter Simmonds, Paul R Clapham Retrovirology 2012, 9:20 (15 March 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This study shows that non-macrophage-tropic R5 envelopes carrying gp120s with an increased positive charge were predominant in immune tissue in late disease. However, highly macrophage-tropic variants with lower charged gp120s were nearly universal in the brain.
		Commentary New and novel intrinsic host repressive factors against HIV-1: PAF1 complex, HERC5 and others Mudit Tyagi, Fatah Kashanchi Retrovirology 2012, 9:19 (9 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary A new strategy of screening using siRNA libraries has been employed to score for suppression of host restriction factors, ultimately leading to activation of the virus. This novel approach has now identified specific critical factors that may be part of the intracellular innate response to HIV-1 infection.
		Research Quantification system for the viral dynamics of a highly pathogenic simian/human immunodeficiency virus based on an in vitro experiment and a mathematical model Shingo Iwami, Benjamin P Holder, Catherine AA Beauchemin, Satoru Morita, Tetsuko Tada, Kei Sato, Tatsuhiko Igarashi, Tomoyuki Miura Retrovirology 2012, 9:18 (25 February 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary In this paper, the authors derived several useful numbers of interested to virologists. They found that an SHIV infected cell has a half-life of 14.1 hour, a virus burst size of 22.1 thousand RNA copies, and can spread the infection to 62.8 uninfected cells.

	All
		Research T cell independent secondary antibody responses to the envelope protein of simian immunodeficiency virus Ghulam Nabi, Vladimir Temchura, Claudius Großmann, Seraphin Kuate, Matthias Tenbusch, Klaus Überla Retrovirology 2012, 9:42 (14 May 2012) Abstract \| Provisional PDF \| Editor’s summary Membrane-bound trimeric Env seems to be responsible for the maintenance of high levels of anti-Env antibodies during progression to AIDS. This T cell independent secondary antibody response may prevent T cell-dependent affinity maturation and thus contribute to viral immune escape by favoring persistence of non-protective antibodies.
		Research The prototype foamy virus protease is active independently of the integrase domain Ralf Spannaus, Maximilian J. Hartl, Birgitta M. Wöhrl, Axel Rethwilm, Jochen Bodem Retrovirology 2012, 9:41 (10 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This paper shows that the FV integrase is required for Pol encapsidation and that the FV PR activity is integrase independent. The study shows that an active PR can be encapsidated in trans as a GagPR-RT fusion protein.
		Research Limited SHIV env diversification in macaques failing oral antiretroviral pre-exposure prophylaxis Qi Zheng, Susan Ruone, William M Switzer, Walid Heneine, J Gerardo García-Lerma Retrovirology 2012, 9:40 (9 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary Infection during pre-exposure prophylaxis (PrEP) limits early virus evolution likely because of a direct antiviral effect of PrEP and/or reduced target cell availability. Reduced virus diversification during early infection might enhance immune control by slowing the selection of escape mutants
		Review HLA-C and HIV-1: Friends or Foes? Donato Zipeto, Alberto Beretta Retrovirology 2012, 9:39 (9 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This review highlights the role of HLA-C in association with HIV-1 viral load, but also addresses the contradiction of the association between high cell surface expression of an inhibitory molecule and strong cell-mediated immunity. To explore additional mechanisms of control of HIV-1 replication by HLA-C, this review addresses specific features of the molecule, like its tendency to be expressed as open conformer upon cell activation, which endows it with a unique capacity to associate with other cell surface molecules as well as with HIV-1 proteins.
		Research HIV-1-encoded antisense RNA suppresses viral replication for a prolonged period Mie Kobayashi-Ishihara, Makoto Yamagishi, Takuma Hara, Yuka Matsuda, Ryutaro Takahashi, Ariko Miyake, Kazumi Nakano, Tadanori Yamochi, Takaomi Ishida, Toshiki Watanabe Retrovirology 2012, 9:38 (8 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary The present study identified an accurate structure of the major form of antisense RNAs expressed from the HIV-1NL4-3 provirus and demonstrated a new role of the antisense RNA in viral replication, suggesting a novel viral mechanism that regulates self-limited replication of HIV-1.
		Research Protein kinase C-delta regulates HIV-1 replication at an early post-entry step in macrophages Xavier Contreras, Olfa Mzoughi, Fabrice Gaston, B Matija Peterlin, Elmostafa Bahraoui Retrovirology 2012, 9:37 (3 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This study identified PKC-delta as a major cellular cofactor for HIV-1 replication in macrophages. PKC-delta was stimulated following the interaction between the virus and its target cell. Inhibition of PKC-delta blocked the replication of R5-tropic viruses in primary human macrophages.
		Research MiniCD4 protein resistance mutations affect binding to the HIV-1 gp120 CD4 binding site and decrease entry efficiency Katrijn Grupping, Philippe Selhorst, Johan Michiels, Katleen Vereecken, Leo Heyndrickx, Pascal Kessler, Guido Vanham, Loïc Martin, Kevin K Ariën Retrovirology 2012, 9:36 (2 May 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary The present study reports on the resistance induction of two subtype B HIV-1 against the most active miniCD4, M48U1, and its ancestor, M48, and how these mutated positions affect CD4bs recognition, entry efficiency, and sensitivity to other CD4bs inhibitors. Resistance against M48U1 was always associated with S375R/N substitution in both BaL and SF162; M48 resistance was associated with D474N substitution in SF162 and with H105Y substitution in BaL.
		Review Emerging complexities of APOBEC3G action on immunity and viral fitness during HIV infection and treatment Mahdis Monajemi, Claire F Woodworth, Jessica Benkaroun, Michael Grant, Mani Larijani Retrovirology 2012, 9:35 (30 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary Despite its effectiveness in various experimental systems, numerous recent studies have shown that the ability of A3G to combat HIV in the physiological setting is severely limited. In fact, it has become apparent that A3G's mutational activity may actually enhance viral fitness by accelerating HIV evolution towards the evasion of both anti-viral drugs and the immune system. Here the authors present an overview of recent data that bring to light historical overestimation of A3G's standing as a strictly anti-viral agent.
		Research Identification of a highly conserved valine-glycine-phenylalanine amino acid triplet required for HIV-1 Nef function Pieter J Meuwissen, Bettina Stolp, Veronica Iannucci, Jolien Vermeire, Evelien Naessens, Kalle Saksela, Matthias Geyer, Guido Vanham, Kevin K Arien, Oliver T Fackler, Bruno Verhasselt Retrovirology 2012, 9:34 (27 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This study describes a highly conserved three amino acid VGF motif that together with the acidic cluster and the proline-rich motif form a previously unrecognized amphipathic surface on Nef. This surface appears to be essential for the majority of Nef functions and thus represents a prime target for the pharmacological inhibition of Nef.
		Research Proteomic analysis of HIV-1 Nef cellular binding partners reveals a role for exocyst complex proteins in mediating enhancement of intercellular nanotube formation Joya Mukerji, Kevin C Olivieri, Vikas Misra, Kristin A Agopian, Dana Gabuzda Retrovirology 2012, 9:33 (25 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary To identify Nef binding partners involved in Pak2-association dependent Nef functions, the authors employed tandem mass spectrometry analysis of Nef immunocomplexes from Jurkat cells expressing wild-type Nef or Nef mutants defective for the ability to associate with Pak2 (F85L, F89H, H191F and A72P, A74P in NL4-3). They report that wild-type, but not mutant Nef, was associated with 5 components of the exocyst complex (EXOC1, EXOC2, EXOC3, EXOC4, and EXOC6), an octameric complex that tethers vesicles at the plasma membrane, regulates polarized exocytosis, and recruits membranes and proteins required for nanotube formation.
		Research Vpx is Critical for SIVmne infection of pigtail macaques Michael Belshan, Jason T Kimata, Charles Brown, Xiaogang Cheng, Anna McCulley, Alison Larsen, Rajesh Thippeshappa, Vida Hodara, Luis Giavedoni, Vanessa Hirsch, Lee Ratner Retrovirology 2012, 9:32 (24 April 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary This work demonstrates that the activities of Vpx to overcome restrictions in culture in vitro are also likely to be important for establishment of infection in vivo and suggest that both the nuclear localization and DCAF1-interaction functions of Vpx are critical in vivo
		Research Stable multi-infection of splenocytes during SIV infection - the basis for continuous recombination Anke Schultz, Sieghart Sopper, Ulrike Sauermann, Andreas Meyerhans, Rodolphe Suspene Retrovirology 2012, 9:31 (23 April 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary SIV multi-infection of single splenocytes was readily detected in all monkeys and all stages of the infection. Single-infected cells were more frequent than double or triple infected cells. There was no strong trend linking the copy number distribution to plasma viral load, disease stage or CD4 cell counts.
		Research Second-site suppressors of HIV-1 capsid mutations: restoration of intracellular activities without correction of intrinsic capsid stability defects Ruifeng Yang, Jiong Shi, In-Ja L Byeon, Jinwoo Ahn, Jonathan H Sheehan, Jens Meiler, Angela M Gronenborn, Christopher Aiken Retrovirology 2012, 9:30 (19 April 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary The second-site suppressor mutations in CA identified here rescue virus infection without correcting the intrinsic capsid stability defects associated with the P38A and E45A mutations. The suppressors also restored wild type virus function in several cell-based assays. Thus, while proper HIV-1 uncoating in target cells is dependent on the intrinsic stability of the viral capsid, the effects of stability-altering mutations can be mitigated by additional mutations that affect interactions with host factors in target cells or the consequences of these interactions.
		Research Modulation of HIV-1 Gag NC/p1 cleavage efficiency affects protease inhibitor resistance and viral replicative capacity Noortje M van Maarseveen, Dan Andersson, Martin Lepšík, Axel Fun, Pauline J Schipper, Dorien de Jong, Charles AB Boucher, Monique Nijhuis Retrovirology 2012, 9:29 (1 April 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary The authors show that single NC/p1 mutants, which displayed only a slight increase in protease inhibitor (PI) resistance didn't show an obvious change in replicative capacity (RC), but that double NC/p1 mutant which displayed a clear increase in processing efficiency and PI resistance did have a clear reduction in RC.
		Research New STLV-3 strains and a divergent SIVmus strain identified in non-human primate bushmeat in Gabon Florian Liegeois, Vanina Boue, Fatima Mouacha, Christelle Butel, Bertrand Mve-Ondo, Xavier Pourrut, Eric Leroy, Martine Peeters, Francois Rouet Retrovirology 2012, 9:28 (30 March 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary SIV and STLV antibodies were detected by HIV and HTLV antigens and PCRs were performed on samples with an HIV or/and HTLV-like or indeterminate profile. Fourteen percent of the samples cross-reacted with HIV antigens and 44% with HTLV antigens. The authors report STLV-1 infections in five of the seven species tested. STLV3 infections, including a new STLV 3 subtype, STLV-1 and 3 co-infections and triple SIV, STLV-1, STLV-3 infections.
		Research Tailored enrichment strategy detects low abundant small noncoding RNAs in HIV-1 infected cells Claudia F Althaus, Valentina Vongrad, Barbara Niederöst, Beda Joos, Francesca Di Giallonardo, Philip Rieder, Jovan Pavlovic, Alexandra Trkola, Huldrych F Günthard, Karin J Metzner, Marek Fischer Retrovirology 2012, 9:27 (29 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary 892 individual HIV-1 sncRNAs were cloned and sequenced from nine different sncRNA libraries derived from five independent experiments. They are spread throughout the HIV-1 genome, however, forming certain clusters, and almost 10% show an antisense orientation. The results show that HIV-1 infected cells generate virally encoded sncRNAs, which might play a role in the HIV-1 life cycle.
		Research Host-pathogen interactome mapping for HTLV-1 and -2 retroviruses Nicolas Simonis, Jean-François Rual, Irma Lemmens, Mathieu Boxus, Tomoko Hirozane-Kishikawa, Jean-Stéphane Gatot, Amélie Dricot, Tong Hao, Didier Vertommen, Sébastien Legros, Sarah Daakour, Niels Klitgord, Maud Martin, Jean-François Willaert, Franck Dequiedt, Vincent Navratil, Michael E Cusick, Arsène Burny, Carine Van Lint, David E Hill, Jan Tavernier, Richard Kettmann, Marc Vidal, Jean-Claude Twizere Retrovirology 2012, 9:26 (29 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary This work employed a scalable methodology for the systematic mapping and comparison of pathogen-host protein interactions that includes stringent yeast two-hybrid screening and systematic retest, as well as two independent validations through an additional protein interaction detection method and a functional transactivation assay. The authors found 166 interactions between 10 viral proteins and 122 human proteins.
		Viewpoints Viewpoint on Emv2, the onlhy endogenous ecotropic murine leukemia virus of C57BL/6 mice Christine A Kozak Retrovirology 2012, 9:25 (22 March 2012) Abstract \| Full text \| PDF \| PubMed \| 2 comments \| Editor’s summary Kozak comments on the discussion between Young et al. and Lee and Cho.
		Correspondence Reply to Emv2, the only endogenous ecotropic murine leukemia virus of C57BL/6J mice Kang-Hoon Lee, Kiho Cho Retrovirology 2012, 9:24 (22 March 2012) Abstract \| Full text \| PDF \| PubMed \| Cited on BioMed Central \| Editor’s summary Lee and Cho reply to the correspondence by Young et al.
		Correspondence Emv2, the only endogenous ecotropic murine leukemia virus of C57BL/6J mice George R Young, George Kassiotis, Jonathan P Stoye Retrovirology 2012, 9:23 (22 March 2012) Abstract \| Full text \| PDF \| PubMed \| Cited on BioMed Central \| Editor’s summary The authors suggest that due diligence has not been applied in a recent description by Cho et al. of an endogenous ecotropic retrovirus that was published in Retrovirology.
		Research Timing and source of subtype-C HIV-1 superinfection in the newly infected partner of Zambian couples with disparate viruses Colleen S Kraft, Debby Basu, Paulina A Hawkins, Peter T Hraber, Elwyn Chomba, Joseph Mulenga, William Kilembe, Naw H Khu, Cynthia A Derdeyn, Susan A Allen, Olivier Manigart, Eric Hunter Retrovirology 2012, 9:22 (20 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary In this subtype-C discordant couple cohort, superinfection, during the first year after HIV-1 infection of the previously negative partner, occurred at a rate similar to primary infection (13.6% [95% CI 5.2-34.8] vs 7.8% [7.1-8.6]). While limited intra-couple superinfection may in part reflect continued condom usage within couples, this and our lack of detecting newly superinfected individuals after one year of primary infection raises the possibility that immunological resistance to intra-subtype superinfection may develop over time in subtype C infected individuals.
		Research The endogenous retrovirus ENS-1 provides active binding sites for transcription factors in embryonic stem cells that specify extra embryonic tissue Anne Mey, Herve Acloque, Emmanuelle Lerat, Sebastien Gounel, Violaine Tribollet, Sophie Blanc, Damien Curton, Anne-Marie Birot, M Angela Nieto, Jacques Samarut Retrovirology 2012, 9:21 (15 March 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary The authors show that Ens-1 LTR activity is controlled by two transcriptional pathways that drive pluripotent cells to alternative developmental fates.
		Research Independent evolution of macrophage-tropism and increased charge between HIV-1 R5 envelopes present in brain and immune tissue Maria P Gonzalez-Perez, Olivia J O'Connell, Rongheng Lin, William M Sullivan, Jeanne Bell, Peter Simmonds, Paul R Clapham Retrovirology 2012, 9:20 (15 March 2012) Abstract \| Provisional PDF \| PubMed \| Editor’s summary This study shows that non-macrophage-tropic R5 envelopes carrying gp120s with an increased positive charge were predominant in immune tissue in late disease. However, highly macrophage-tropic variants with lower charged gp120s were nearly universal in the brain.
		Commentary New and novel intrinsic host repressive factors against HIV-1: PAF1 complex, HERC5 and others Mudit Tyagi, Fatah Kashanchi Retrovirology 2012, 9:19 (9 March 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary A new strategy of screening using siRNA libraries has been employed to score for suppression of host restriction factors, ultimately leading to activation of the virus. This novel approach has now identified specific critical factors that may be part of the intracellular innate response to HIV-1 infection.
		Research Quantification system for the viral dynamics of a highly pathogenic simian/human immunodeficiency virus based on an in vitro experiment and a mathematical model Shingo Iwami, Benjamin P Holder, Catherine AA Beauchemin, Satoru Morita, Tetsuko Tada, Kei Sato, Tatsuhiko Igarashi, Tomoyuki Miura Retrovirology 2012, 9:18 (25 February 2012) Abstract \| Full text \| PDF \| PubMed \| Editor’s summary In this paper, the authors derived several useful numbers of interested to virologists. They found that an SHIV infected cell has a half-life of 14.1 hour, a virus burst size of 22.1 thousand RNA copies, and can spread the infection to 62.8 uninfected cells.