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Albendazole treatment of HIV-1 and helminth co-infection: a randomized, double-blind, placebo-controlled trial. AIDS 2008; 22:1601-9. [PMID: 18670219 DOI: 10.1097/qad.0b013e32830a502e] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
OBJECTIVE Several co-infections have been shown to impact the progression of HIV-1 infection. We sought to determine if treatment of helminth co-infection in HIV-1-infected adults impacted markers of HIV-1 disease progression. DESIGN To date, there have been no randomized trials to examine the effects of soil-transmitted helminth eradication on markers of HIV-1 progression. METHODS A randomized, double-blind, placebo-controlled trial of albendazole (400 mg daily for 3 days) in antiretroviral-naive HIV-1-infected adults (CD4 cell count >200 cells/microl) with soil-transmitted helminth infection was conducted at 10 sites in Kenya (ClinicalTrials.gov NCT00130910). CD4 and plasma HIV-1 RNA levels at 12 weeks following randomization were compared in the trial arms using linear regression, adjusting for baseline values. RESULTS Of 1551 HIV-1-infected individuals screened for helminth infection, 299 were helminth infected. Two hundred and thirty-four adults were enrolled and underwent randomization and 208 individuals were included in intent-to-treat analyses. Mean CD4 cell count was 557 cells/microl and mean plasma viral load was 4.75 log10 copies/ml at enrollment. Albendazole therapy resulted in significantly higher CD4 cell counts among individuals with Ascaris lumbricoides infection after 12 weeks of follow-up (+109 cells/microl; 95% confidence interval +38.9 to +179.0, P = 0.003) and a trend for 0.54 log10 lower HIV-1 RNA levels (P = 0.09). These effects were not seen with treatment of other species of soil-transmitted helminths. CONCLUSION Treatment of A. lumbricoides with albendazole in HIV-1-coinfected adults resulted in significantly increased CD4 cell counts during 3-month follow-up. Given the high prevalence of A. lumbricoides infection worldwide, deworming may be an important potential strategy to delay HIV-1 progression.
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252
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Van Geertruyden JP, Menten J, Colebunders R, Korenromp E, D'Alessandro U. The impact of HIV-1 on the malaria parasite biomass in adults in sub-Saharan Africa contributes to the emergence of antimalarial drug resistance. Malar J 2008; 7:134. [PMID: 18647387 PMCID: PMC2517597 DOI: 10.1186/1475-2875-7-134] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2008] [Accepted: 07/22/2008] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND HIV-related immune-suppression increases the risk of malaria (infection, disease and treatment failure) and probably the circulating parasite biomass, favoring the emergence of drug resistance parasites. METHODS The additional malaria parasite biomass related to HIV-1 co-infection in sub-Saharan Africa was estimated by a mathematical model. Parasite biomass was computed as the incidence rate of clinical malaria episodes multiplied by the number of parasites circulating in the peripheral blood of patients at the time symptoms appear. A mathematical model estimated the influence of HIV-1 infection on parasite density in clinical malaria by country and by age group, malaria transmission intensity and urban/rural area. In a multivariate sensitivity analysis, 95% confidence intervals (CIs) were calculated using the Monte Carlo simulation. RESULTS The model shows that in 2005 HIV-1 increased the overall malaria parasite biomass by 18.0% (95%CI: 11.6-26.9). The largest relative increase (134.9-243.9%) was found in southern Africa where HIV-1 prevalence is the highest and malaria transmission unstable. The largest absolute increase was found in Zambia, Malawi, the Central African Republic and Mozambique, where both malaria and HIV are highly endemic. A univariate sensitivity analysis shows that estimates are sensitive to the magnitude of the impact of HIV-1 infection on the malaria incidence rates and associated parasite densities. CONCLUSION The HIV-1 epidemic by increasing the malaria parasite biomass in sub-Saharan Africa may also increase the emergence of antimalarial drug resistance, potentially affecting the health of the whole population in countries endemic for both HIV-1 and malaria.
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Affiliation(s)
- Jean-Pierre Van Geertruyden
- Department of Parasitology, Unit of Epidemiology Institute of Tropical Medicine Antwerpen, Nationalestraat 155 B2000, Antwerpen, Belgium.
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He W, Neil S, Kulkarni H, Wright E, Agan BK, Marconi VC, Dolan MJ, Weiss RA, Ahuja SK. Duffy antigen receptor for chemokines mediates trans-infection of HIV-1 from red blood cells to target cells and affects HIV-AIDS susceptibility. Cell Host Microbe 2008; 4:52-62. [PMID: 18621010 PMCID: PMC2562426 DOI: 10.1016/j.chom.2008.06.002] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 04/27/2008] [Accepted: 06/17/2008] [Indexed: 01/12/2023]
Abstract
Duffy antigen receptor for chemokines (DARC) expressed on red blood cells (RBCs) influences plasma levels of HIV-1-suppressive and proinflammatory chemokines such as CCL5/RANTES. DARC is also the RBC receptor for Plasmodium vivax. Africans with DARC -46C/C genotype, which confers a DARC-negative phenotype, are resistant to vivax malaria. Here, we show that HIV-1 attaches to RBCs via DARC, effecting trans-infection of target cells. In African Americans, DARC -46C/C is associated with 40% increase in the odds of acquiring HIV-1. If extrapolated to Africans, approximately 11% of the HIV-1 burden in Africa may be linked to this genotype. After infection occurs, however, DARC-negative RBC status is associated with slower disease progression. Furthermore, the disease-accelerating effect of a previously described CCL5 polymorphism is evident only in DARC-expressing and not in DARC-negative HIV-infected individuals. Thus, DARC influences HIV/AIDS susceptibility by mediating trans-infection of HIV-1 and by affecting both chemokine-HIV interactions and chemokine-driven inflammation.
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Affiliation(s)
- Weijing He
- Veterans Administration Research Center for AIDS and HIV-1 Infection, South Texas Veterans Health Care System, San Antonio, TX 78229, USA
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Castilho PC, Gouveia SC, Rodrigues AI. Quantification of artemisinin in Artemisia annua extracts by 1H-NMR. PHYTOCHEMICAL ANALYSIS : PCA 2008; 19:329-334. [PMID: 18197598 DOI: 10.1002/pca.1053] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/25/2023]
Abstract
Artemisinin is a polycyclic sesquiterpene lactone that is highly effective against multidrug-resistant strains of Plasmodium falciparum, the etiological agent of the most severe form of malaria. Determination of artemisinin in the source plant, Artemisia annua, is a challenging problem since the compound is present in very low concentrations, is thermolabile and unstable, and lacks chromophoric or fluorophoric groups. The ain of this study was to develop a simple protocol for the quantification of artemisinin in a plant extract using an (1)H-NMR method. Samples were prepared by extraction of leaf material with acetone, treatment with activated charcoal to remove chlorophylls and removal of solvent. (1)H-NMR spectra were measured on samples dissolved in deuterochloroform with tert-butanol as internal standard. Quantification was carried out using the using the delta 5.864 signal of artemisinin and the delta 1.276 signal of tert-butanol. The method was optimised and fully validated against a reference standard of artemisinin. The results were compared with those obtained from the same samples quantified using an HPLC-refractive index (RI) method. The (1)H-NMR method gave a linear response for artemisinin within the range 9.85-97.99 mm (r(2) = 0.9968). Using the described method, yields of artemisinin in the range 0.77-1.06% were obtained from leaves of the A. annua hybrid CPQBA x POP, and these values were in agreement with those obtained using an HPLC-RI.
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Affiliation(s)
- Paula C Castilho
- Centro de Química da Madeira, Departamento de Química, Universidade da Madeira, Campus Universitário da Penteada, piso 0, 9000-390 Funchal, Portugal.
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255
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Coleman CA, Muller-Trutwin MC, Apetrei C, Pandrea I. T regulatory cells: aid or hindrance in the clearance of disease? J Cell Mol Med 2008; 11:1291-325. [PMID: 18205702 PMCID: PMC4401294 DOI: 10.1111/j.1582-4934.2007.00087.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
CD4+ CD25+ T regulatory cells (Tregs) are classified as a subset of T cells whose role is the suppression and regulation of immune responses to self and non-self. Since their discovery in the early 1970s, the role of CD4+ CD25+ Tregs in both autoimmune and infectious disease has continued to expand. This review exam-ines the recent advances on the role CD4+ CD25+ Tregs may be playing in various diseases regarding pro-gression or protection. In addition, advances made in the purification and manipulation of CD4+ CD25+ Tregs using new cell markers, techniques and antibodies are discussed. Ultimately, an overall understanding of the exact mechanism which CD4+ CD25+ Tregs implement during disease progression will enhance our ability to manipulate CD4+ CD25+ Tregs in a clinically beneficial manner.
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Affiliation(s)
- Clint A Coleman
- Department of Microbiology and Immunology, Tulane University Health Sciences Center, New Orleans, LA, USA
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256
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Lello J, Hussell T. Functional group/guild modelling of inter-specific pathogen interactions: a potential tool for predicting the consequences of co-infection. Parasitology 2008; 135:825-39. [PMID: 18477416 DOI: 10.1017/s0031182008000383] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Although co-infection is the norm in most human and animal populations, clinicians currently have no practical tool to assist them in choosing the best treatment strategy for such patients. Given the vast range of potential pathogens which may co-infect the host, obtaining such a practical tool may seem an intractable problem. In ecology the joint concepts of functional groups and guilds have been used to conceptually simplify complex ecosystems, in order to understand how their component parts interact and may be manipulated. Here we propose a mechanism by which to apply these concepts to pathogen co-infection systems. Further, we describe how these groups could be incorporated into a mathematical modelling framework which, after validation, could be used as a clinical tool to predict the outcome of any particular combination of pathogens co-infecting a host.
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Affiliation(s)
- J Lello
- School of Biosciences, Cardiff University, Biomedical Sciences Building, Museum Avenue, Cardiff, CF10 3US.
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257
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Abstract
OBJECTIVE To estimate the role of each of the HIV progression stages in fueling HIV transmission in sub-Saharan Africa by using the recent measurements of HIV transmission probability per coital per HIV stage in the Rakai study. METHODS A mathematical model, parameterized by empirical data from the Rakai, Masaka, and Four-City studies, was used to estimate the proportion of infections due to each of the HIV stages in two representative epidemics in sub-Saharan Africa. The first setting represents a hyperendemic HIV epidemic (Kisumu, Kenya) whereas the second setting represents a generalized but not hyperendemic HIV epidemic (Yaoundé, Cameroon). RESULTS We estimate that 17, 51, and 32% of HIV transmissions in Kisumu were due to index cases in their acute, latent, and late stages, respectively. In Yaoundé, the fractions were 25, 44, and 31%. We found that the relative contribution of each stage varied with the epidemic evolution with the acute stage prevailing early on when the infection is concentrated in the high-risk groups with the late stage playing a major role as the epidemic matured and stabilized. The latent stage contribution remained largely stable throughout the epidemic and contributed about half of all transmissions. CONCLUSION No HIV stage dominated the epidemical though the latent stage provided the largest contribution. The role of each stage depends on the phase of the epidemic and on the prevailing levels of sexual risk behavior in the populations in which HIV is spreading. These findings may influence the design and implementation of different HIV interventions.
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258
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Abu-Raddad LJ, Magaret AS, Celum C, Wald A, Longini IM, Self SG, Corey L. Genital herpes has played a more important role than any other sexually transmitted infection in driving HIV prevalence in Africa. PLoS One 2008; 3:e2230. [PMID: 18493617 PMCID: PMC2377333 DOI: 10.1371/journal.pone.0002230] [Citation(s) in RCA: 196] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2007] [Accepted: 03/28/2008] [Indexed: 11/18/2022] Open
Abstract
Background Extensive evidence from observational studies suggests a role for genital herpes in the HIV epidemic. A number of herpes vaccines are under development and several trials of the efficacy of HSV-2 treatment with acyclovir in reducing HIV acquisition, transmission, and disease progression have just reported their results or will report their results in the next year. The potential impact of these interventions requires a quantitative assessment of the magnitude of the synergy between HIV and HSV-2 at the population level. Methods and Findings A deterministic compartmental model of HIV and HSV-2 dynamics and interactions was constructed. The nature of the epidemiologic synergy was explored qualitatively and quantitatively and compared to other sexually transmitted infections (STIs). The results suggest a more substantial role for HSV-2 in fueling HIV spread in sub-Saharan Africa than other STIs. We estimate that in settings of high HSV-2 prevalence, such as Kisumu, Kenya, more than a quarter of incident HIV infections may have been attributed directly to HSV-2. HSV-2 has also contributed considerably to the onward transmission of HIV by increasing the pool of HIV positive persons in the population and may explain one-third of the differential HIV prevalence among the cities of the Four City study. Conversely, we estimate that HIV had only a small net impact on HSV-2 prevalence. Conclusions HSV-2 role as a biological cofactor in HIV acquisition and transmission may have contributed substantially to HIV particularly by facilitating HIV spread among the low-risk population with stable long-term sexual partnerships. This finding suggests that prevention of HSV-2 infection through a prophylactic vaccine may be an effective intervention both in nascent epidemics with high HIV incidence in the high risk groups, and in established epidemics where a large portion of HIV transmission occurs in stable partnerships.
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Affiliation(s)
- Laith J Abu-Raddad
- Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington, United States of America.
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259
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Skinner-Adams TS, McCarthy JS, Gardiner DL, Andrews KT. HIV and malaria co-infection: interactions and consequences of chemotherapy. Trends Parasitol 2008; 24:264-71. [PMID: 18456554 DOI: 10.1016/j.pt.2008.03.008] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2007] [Revised: 02/12/2008] [Accepted: 03/10/2008] [Indexed: 10/22/2022]
Abstract
The global epidemiology of HIV/AIDS and malaria overlap because a significant number of HIV-infected individuals live in regions with different levels of malaria transmission. Although the consequences of co-infection with HIV and malaria parasites are not fully understood, available evidence suggests that the infections act synergistically and together result in worse outcomes. The importance of understanding chemotherapeutic interactions during malaria and HIV co-infection is now being recognized. We know that some antimalarial drugs have weak antiretroviral effects; however, recent studies have also demonstrated that certain antiretroviral agents can inhibit malaria-parasite growth. Here, we discuss recent findings on the impact of HIV/AIDS and malaria co-infection and the possible roles of chemotherapy in improving the treatment of these diseases.
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260
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Abu-Raddad LJ, van der Ventel BIS, Ferguson NM. Interactions of multiple strain pathogen diseases in the presence of coinfection, cross immunity, and arbitrary strain diversity. PHYSICAL REVIEW LETTERS 2008; 100:168102. [PMID: 18518250 DOI: 10.1103/physrevlett.100.168102] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2007] [Indexed: 05/26/2023]
Abstract
A model for coinfection in multiple strain infectious diseases is developed to incorporate coinfection statuses, immune and infection history, and cross immunity. It is solved for the symmetric interior equilibrium through the use of a ladder operator formalism inspired by quantum mechanical methods. We find that coinfection can fundamentally affects transmission dynamics with important epidemiologic and evolutionary consequences. It can significantly shift the distribution of age at infection for highly antigenically diverse pathogens so that in small host populations, an evolutionary strategy maximizing individual strain transmissibility might be less optimal than one which maximizes the total prevalence of all strains in the system. Alternatively, mechanisms which inhibit coinfection and thus increase total infection prevalence may be evolutionarily advantageous.
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Affiliation(s)
- L J Abu-Raddad
- Vaccine and Infectious Disease Institute, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA.
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261
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Cohen MS, Hellmann N, Levy JA, DeCock K, Lange J. The spread, treatment, and prevention of HIV-1: evolution of a global pandemic. J Clin Invest 2008; 118:1244-54. [PMID: 18382737 PMCID: PMC2276790 DOI: 10.1172/jci34706] [Citation(s) in RCA: 147] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The most up-to-date estimates demonstrate very heterogeneous spread of HIV-1, and more than 30 million people are now living with HIV-1 infection, most of them in sub-Saharan Africa. The efficiency of transmission of HIV-1 depends primarily on the concentration of the virus in the infectious host. Although treatment with antiviral agents has proven a very effective way to improve the health and survival of infected individuals, as we discuss here, the epidemic will continue to grow unless greatly improved prevention strategies can be developed and implemented. No prophylactic vaccine is on the horizon. However, several behavioral and structural strategies have made a difference--male circumcision provides substantial protection from sexually transmitted diseases, including HIV-1, and the application of antiretroviral agents for prevention holds great promise.
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Affiliation(s)
- Myron S Cohen
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27514, USA.
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262
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Giacaman RA, Asrani AC, Gebhard KH, Dietrich EA, Vacharaksa A, Ross KF, Herzberg MC. Porphyromonas gingivalis induces CCR5-dependent transfer of infectious HIV-1 from oral keratinocytes to permissive cells. Retrovirology 2008; 5:29. [PMID: 18371227 PMCID: PMC2292744 DOI: 10.1186/1742-4690-5-29] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2007] [Accepted: 03/27/2008] [Indexed: 01/14/2023] Open
Abstract
Background Systemic infection with HIV occurs infrequently through the oral route. The frequency of occurrence may be increased by concomitant bacterial infection of the oral tissues, since co-infection and inflammation of some cell types increases HIV-1 replication. A putative periodontal pathogen, Porphyromonas gingivalis selectively up-regulates expression of the HIV-1 coreceptor CCR5 on oral keratinocytes. We, therefore, hypothesized that P. gingivalis modulates the outcome of HIV infection in oral epithelial cells. Results Oral and tonsil epithelial cells were pre-incubated with P. gingivalis, and inoculated with either an X4- or R5-type HIV-1. Between 6 and 48 hours post-inoculation, P. gingivalis selectively increased the infectivity of R5-tropic HIV-1 from oral and tonsil keratinocytes; infectivity of X4-tropic HIV-1 remained unchanged. Oral keratinocytes appeared to harbor infectious HIV-1, with no evidence of productive infection. HIV-1 was harbored at highest levels during the first 6 hours after HIV exposure and decreased to barely detectable levels at 48 hours. HIV did not appear to co-localize with P. gingivalis, which increased selective R5-tropic HIV-1 trans infection from keratinocytes to permissive cells. When CCR5 was selectively blocked, HIV-1 trans infection was reduced. Conclusion P. gingivalis up-regulation of CCR5 increases trans infection of harbored R5-tropic HIV-1 from oral keratinocytes to permissive cells. Oral infections such as periodontitis may, therefore, increase risk for oral infection and dissemination of R5-tropic HIV-1.
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Affiliation(s)
- Rodrigo A Giacaman
- Department of Diagnostic and Biological Sciences, School of Dentistry, University of Minnesota, Minneapolis, MN 55455, USA.
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263
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Abstract
SUMMARYHIV-1 and parasitic infections co-circulate in many populations, and in a few well-studied examples HIV-1 co-infection is known to amplify parasite transmission. There are indications that HIV-1 interacts significantly with many other parasitic infections within individual hosts, but the population-level impacts of co-infection are not well-characterized. Here we consider how alteration of host immune status due to HIV-1 infection may influence the emergence of novel parasite strains. We review clinical and epidemiological evidence from five parasitic diseases (malaria, leishmaniasis, schistosomiasis, trypanosomiasis and strongyloidiasis) with emphasis on how HIV-1 co-infection alters individual susceptibility and infectiousness for the parasites. We then introduce a simple modelling framework that allows us to project how these individual-level properties might influence population-level dynamics. We find that HIV-1 can facilitate invasion by parasite strains in many circumstances and we identify threshold values of HIV-1 prevalence that allow otherwise unsustainable parasite strains to invade successfully. Definitive evidence to test these predicted effects is largely lacking, and we conclude by discussing challenges in interpreting available data and priorities for future studies.
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264
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When did HIV incidence peak in Harare, Zimbabwe? Back-calculation from mortality statistics. PLoS One 2008; 3:e1711. [PMID: 18320032 PMCID: PMC2248619 DOI: 10.1371/journal.pone.0001711] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2007] [Accepted: 01/01/2008] [Indexed: 11/21/2022] Open
Abstract
HIV prevalence has recently begun to decline in Zimbabwe, a result of both high levels of AIDS mortality and a reduction in incident infections. An important component in understanding the dynamics in HIV prevalence is knowledge of past trends in incidence, such as when incidence peaked and at what level. However, empirical measurements of incidence over an extended time period are not available from Zimbabwe or elsewhere in sub-Saharan Africa. Using mortality data, we use a back-calculation technique to reconstruct historic trends in incidence. From AIDS mortality data, extracted from death registration in Harare, together with an estimate of survival post-infection, HIV incidence trends were reconstructed that would give rise to the observed patterns of AIDS mortality. Models were fitted assuming three parametric forms of the incidence curve and under nine different assumptions regarding combinations of trends in non-AIDS mortality and patterns of survival post-infection with HIV. HIV prevalence was forward-projected from the fitted incidence and mortality curves. Models that constrained the incidence pattern to a cubic spline function were flexible and produced well-fitting, realistic patterns of incidence. In models assuming constant levels of non-AIDS mortality, annual incidence peaked between 4 and 5% between 1988 and 1990. Under other assumptions the peak level ranged from 3 to 8% per annum. However, scenarios assuming increasing levels of non-AIDS mortality resulted in implausibly low estimates of peak prevalence (11%), whereas models with decreasing underlying crude mortality could be consistent with the prevalence and mortality data. HIV incidence is most likely to have peaked in Harare between 1988 and 1990, which may have preceded the peak elsewhere in Zimbabwe. This finding, considered alongside the timing and location of HIV prevention activities, will give insight into the decline of HIV prevalence in Zimbabwe.
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265
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Graham AL. Ecological rules governing helminth-microparasite coinfection. Proc Natl Acad Sci U S A 2008; 105:566-70. [PMID: 18182496 PMCID: PMC2206576 DOI: 10.1073/pnas.0707221105] [Citation(s) in RCA: 267] [Impact Index Per Article: 16.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2007] [Indexed: 11/18/2022] Open
Abstract
Coinfection of a host by multiple parasite species has important epidemiological and clinical implications. However, the direction and magnitude of effects vary considerably among systems, and, until now, there has been no general framework within which to explain this variation. Community ecology has great potential for application to such problems in biomedicine. Here, metaanalysis of data from 54 experiments on laboratory mice reveals that basic ecological rules govern the outcome of coinfection across a broad spectrum of parasite taxa. Specifically, resource-based ("bottom-up") and predator-based ("top-down") control mechanisms combined to determine microparasite population size in helminth-coinfected hosts. Coinfection imposed bottom-up control (resulting in decreased microparasite density) when a helminth that causes anemia was paired with a microparasite species that requires host red blood cells. At the same time, coinfection impaired top-down control of microparasites by the immune system: the greater the helminth-induced suppression of the inflammatory cytokine interferon (IFN)-gamma, the greater the increase in microparasite density. These results suggest that microparasite population growth will be most explosive when underlying helminths do not impose resource limitations but do strongly modulate IFN-gamma responses. Surprisingly simple rules and an ecological framework within which to analyze biomedical data thus emerge from analysis of this dataset. Through such an interdisciplinary lens, predicting the outcome of coinfection may become tractable.
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Affiliation(s)
- Andrea L Graham
- Institute of Evolution, School of Biological Sciences, University of Edinburgh, King's Buildings, Ashworth Laboratories, Edinburgh EH9 3JT, Scotland.
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266
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Shapiro HM, Perlmutter NG. Killer applications: Toward affordable rapid cell-based diagnostics for malaria and tuberculosis. CYTOMETRY PART B-CLINICAL CYTOMETRY 2008; 74 Suppl 1:S152-64. [DOI: 10.1002/cyto.b.20401] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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267
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Bibliography. Current world literature. Neuro-ophthalmology. Curr Opin Ophthalmol 2007; 18:515-17. [PMID: 18163005 DOI: 10.1097/icu.0b013e3282f292cf] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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268
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Long GH, Chan BHK, Allen JE, Read AF, Graham AL. Blockade of TNF receptor 1 reduces disease severity but increases parasite transmission during Plasmodium chabaudi chabaudi infection. Int J Parasitol 2007; 38:1073-81. [PMID: 18226816 DOI: 10.1016/j.ijpara.2007.12.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2007] [Revised: 11/21/2007] [Accepted: 12/06/2007] [Indexed: 11/28/2022]
Abstract
Reducing host carriage of transmission-stage malaria parasites (gametocytes) is expected to decrease the population-wide burden of malaria. Some malaria disease severity is attributed to the induction of the pro-inflammatory cytokines TNF-alpha and lymphotoxin-alpha (LT-alpha), and we are interested in whether anti-malaria interventions which ameliorate the symptoms induced by those cytokines may have the capacity to alter malaria transmission. As many functions of TNF-alpha and LT-alpha are exerted through TNF receptor 1 (TNFR1), we investigated the effect TNFR1 blockade exerted on parasite transmission using the rodent malaria Plasmodium chabaudi chabaudi. We found that blocking TNFR1 simultaneously increased gametocyte density and infectivity to mosquitoes, whilst reducing disease severity (weight loss). These transmission-enhancing and severity-reducing effects of TNFR1 blockade were independent of asexual parasite load and were observed for several P. c. chabaudi genotypes. These results suggest that the effects of candidate malaria interventions on infectivity should be examined alongside effects on disease severity so that the epidemiological consequences of such interventions can be evaluated.
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Affiliation(s)
- Gráinne H Long
- Institutes of Evolution, Immunology and Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JT, Scotland, UK.
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269
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HIV-1 Infection in Patients Referred for Malaria Blood Smears at Government Health Clinics in Uganda. J Acquir Immune Defic Syndr 2007; 46:624-30. [DOI: 10.1097/qai.0b013e31815b2dc5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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270
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Idemyor V. Human immunodeficiency virus (HIV) and malaria interaction in sub-Saharan Africa: the collision of two Titans. HIV CLINICAL TRIALS 2007; 8:246-53. [PMID: 17720665 DOI: 10.1310/hct0804-246] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
HIV and malaria are among the leading causes of morbidity and mortality in sub-Saharan Africa, home to 10% of the world's population. An association between HIV and malaria is expected in theory, however, there is conflicting evidence regarding the impact of HIV infection on parasite loads. HIV-associated immunosuppression contributes to more frequent and more severe malaria and reduced efficacy of antimalarials in pregnant women and adults. These effects are modified by the endemicity and stability of malaria transmission. Co-infection with malaria and HIV in pregnant women is associated with anemia, low birth weight, and increased risk of infant mortality to a greater extent than infection with either disease alone. Studies investigating the impact of placental malaria on mother-to-child HIV-1 transmission continue to show conflicting results. This article attempts to review the pertinent information available about the interaction between HIV and malaria and information about chemoprophylaxis and treatment issues. Although much has been published in the last 10 years regarding the interaction of HIV and malaria in sub-Saharan Africa, we still need more information so as to understand the issues that will help us develop effective programs.
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Affiliation(s)
- Vincent Idemyor
- Visiting Professorship Program and Department of Medicine, University of Port Harcourt and Ahmadu Bello University, Zaria, Nigeria.
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271
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Molecular diagnostic and surveillance tools for global malaria control. Travel Med Infect Dis 2007; 6:82-99. [PMID: 18342279 DOI: 10.1016/j.tmaid.2007.10.001] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2007] [Accepted: 10/09/2007] [Indexed: 01/09/2023]
Abstract
Malaria is the most devastating parasitic infection in the world, annually causing over 1 million deaths and extensive morbidity. The global burden of malaria has increased over the last several decades, as have rates of imported malaria into non-endemic regions. Rapid and accurate diagnostics are a crucial component of malaria control strategies, and epidemiological surveillance is required to monitor trends in malaria prevalence and antimalarial drug resistance. Conventional malaria diagnostic and surveillance tools can be cumbersome and slow with limitations in both sensitivity and specificity. New molecular techniques have been developed in an attempt to overcome these restrictions. These molecular techniques are discussed with regard to their technical advantages and disadvantages, with an emphasis on the practicality of implementation in malaria-endemic and non-endemic regions.
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272
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Cattadori IM, Albert R, Boag B. Variation in host susceptibility and infectiousness generated by co-infection: the myxoma-Trichostrongylus retortaeformis case in wild rabbits. J R Soc Interface 2007; 4:831-40. [PMID: 17580288 PMCID: PMC2386892 DOI: 10.1098/rsif.2007.1075] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
One of the conditions that can affect host susceptibility and parasite transmission is the occurrence of concomitant infections. Parasites interact directly or indirectly within an individual host and often these interactions are modulated by the host immune response. We used a free-living rabbit population co-infected with the nematode Trichostrongylus retortaeformis, which appears to stimulate an acquired immune response, and the immunosuppressive poxvirus myxoma. Modelling was used to examine how myxoma infection alters the immune-mediated establishment and death/expulsion of T. retortaeformis, and consequently affects parasite intensity and duration of the infection. Simulations were based on the general TH1–TH2 immunological paradigm that proposes the polarization of the host immune response towards one of the two subsets of T helper cells. Our findings suggest that myxoma infections contribute to alter host susceptibility to the nematode, as co-infected rabbits showed higher worm intensity compared with virus negative hosts. Results also suggest that myxoma disrupts the ability of the host to clear T. retortaeformis as worm intensities were consistently high and remained high in old rabbits. However, the co-infection model has to include some immune-mediated nematode regulation to be consistent with field data, indicating that the TH1–TH2 dichotomy is not complete. We conclude that seasonal myxoma outbreaks enhance host susceptibility to the nematode and generate highly infected hosts that remain infectious for a longer time. Finally, the virus–nematode co-infection increases heterogeneities among individuals and potentially has a large effect on parasite transmission.
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Affiliation(s)
- Isabella M Cattadori
- Division of Animal Production and Public Health, Faculty of Veterinary Medicine, The University of Glasgow, Glasgow G61 1QH, UK.
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273
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Singer BH, de Castro MC. Bridges to sustainable tropical health. Proc Natl Acad Sci U S A 2007; 104:16038-43. [PMID: 17913894 PMCID: PMC2042158 DOI: 10.1073/pnas.0700900104] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2007] [Indexed: 10/22/2022] Open
Abstract
Ensuring sustainable health in the tropics will require bridge building between communities that currently have a limited track record of interaction. It will also require new organizational innovation if much of the negative health consequences of large-scale economic development projects are to be equitably mitigated, if not prevented. We focus attention on three specific contexts: (i) forging linkages between the engineering and health communities to implement clean water and sanitation on a broad scale to prevent reworming, after the current deworming-only programs, of people by diverse intestinal parasites; (ii) building integrated human and animal disease surveillance infrastructure and technical capacity in tropical countries on the reporting and scientific evidence requirements of the sanitary and phytosanitary agreement under the World Trade Organization; and (iii) developing an independent and equitable organizational structure for health impact assessments as well as monitoring and mitigation of health consequences of economic development projects. Effective global disease surveillance and timely early warning of new outbreaks will require a far closer integration of veterinary and human medicine than heretofore. Many of the necessary surveillance components exist within separate animal- and human-oriented organizations. The challenge is to build the necessary bridges between them.
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Affiliation(s)
- Burton H. Singer
- *Office of Population Research, Princeton University, Wallace Hall, Second Floor, Princeton, NJ 08544; and
| | - Marcia Caldas de Castro
- Department of Population and International Health, Harvard School of Public Health, 665 Huntington Avenue, Building I, Room 1113, Boston, MA 02115
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274
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Martin-Blondel G, Barry M, Porte L, Busato F, Massip P, Benoit-Vical F, Berry A, Marchou B. Impact de l'infection VIH sur l'infection palustre chez l'adulte. Med Mal Infect 2007; 37:629-36. [PMID: 17628374 DOI: 10.1016/j.medmal.2007.03.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2007] [Accepted: 03/29/2007] [Indexed: 11/26/2022]
Abstract
Malaria and HIV are two major public health issues, especially in sub-Saharan Africa. The impact of HIV infection on malaria depends on the patient's immune status: immunodepression level but also immunity against Plasmodium. HIV infection increases the incidence of clinical malaria, inversely correlated with the degree of immunodepression, but the severity and mortality are increased only in areas of unstable malaria. In severe malaria the level of parasitemia is similar in HIV-positive and HIV-negative patients. During pregnancy, HIV infection increases the incidence of clinical malaria, maternal morbidity, and fetal and neonatal morbi-mortality. Sulfa-based therapies reduce the risk of malaria, most importantly in pregnancy. HIV infection increases the risk of treatment failure, mainly with sulfa-based therapies, due to re-infection or parasitic recrudescence. Further studies are needed to determine the pathophysiological interactions between HIV infection and malaria.
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Affiliation(s)
- G Martin-Blondel
- Service des maladies infectieuses et tropicales, hôpital Purpan, place du Docteur-Baylac, TSA 40031, 31059 Toulouse cedex 09, France
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275
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Van geertruyden JP, D'Alessandro U. Malaria and HIV: a silent alliance. Trends Parasitol 2007; 23:465-7. [PMID: 17822960 DOI: 10.1016/j.pt.2007.08.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Revised: 06/27/2007] [Accepted: 08/30/2007] [Indexed: 11/17/2022]
Abstract
HIV and malaria are leading causes of morbidity in sub-Saharan Africa. Recently, Abu-Raddad and colleagues explored the synergy between these diseases through a mathematical model that included all documented interactions. It emerges from the model parameter inputs that concomitant infection of both HIV and malaria fuels the spread of both diseases. For the first time, it is shown that, according to the model, transient but repeatedly elevated HIV viral loads due to recurrent co-infections, such as malaria, can also influence and increase HIV prevalence. Probably, these results are conservative and the true impact of the interaction could be even more important.
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Affiliation(s)
- Jean-Pierre Van geertruyden
- Department Parasitology, Unit of Epidemiology, Institute of Tropical Medicine, Nationalestraat 155, B-2000 Antwerp, Belgium.
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276
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Abu-Raddad LJ, Boily MC, Self S, Longini IM. Analytic insights into the population level impact of imperfect prophylactic HIV vaccines. J Acquir Immune Defic Syndr 2007; 45:454-67. [PMID: 17554215 DOI: 10.1097/qai.0b013e3180959a94] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The population level implications of imperfect HIV vaccines were studied using a mathematical model. A criterion for determining the utility of a vaccine at the population level is introduced, and 2 useful summary measures, namely, vaccine utility (phi) and vaccine infection fitness (psi), are derived and shown to characterize the population-level utility once vaccine efficacies are determined. The utility of the vaccine alone does not guarantee a substantial impact, however, because the effectiveness of partially effective vaccines also depends on the prevailing level of HIV infectious spread. Therefore, a second criterion is introduced through a third summary measure, the hazard index (xi), to describe the effectiveness of a vaccine in substantially reducing HIV incidence. The qualitative features of the impact are delineated by studying 4 distinct scenarios of HIV vaccination. Accordingly, our work delineates the link between vaccine efficacies and the impact of vaccination at the population level and provides the tools for vaccine developers to assess the utility and effectiveness of a given imperfect vaccine straightforwardly and rapidly.
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Affiliation(s)
- Laith J Abu-Raddad
- Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue North LE-400, Seattle, WA 98109, USA.
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277
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Kazembe LN, Muula AS, Appleton CC, Kleinschmidt I. Modelling the effect of malaria endemicity on spatial variations in childhood fever, diarrhoea and pneumonia in Malawi. Int J Health Geogr 2007; 6:33. [PMID: 17651488 PMCID: PMC1963446 DOI: 10.1186/1476-072x-6-33] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2007] [Accepted: 07/25/2007] [Indexed: 11/28/2022] Open
Abstract
Background Co-morbidity with conditions such as fever, diarrhoea and pneumonia is a common phenomenon in tropical Africa. However, little is known about geographical overlaps in these illnesses. Spatial modelling may improve our understanding of the epidemiology of the diseases for efficient and cost-effective control. Methods This study assessed subdistrict-specific spatial associations of the three conditions (fever, diarrhoea and pneumonia) in relation to malaria endemicity. We used data from the 2000 Malawi demographic and health survey which captured the history of childhood morbidities 2 weeks prior to the survey date. The disease status of each child in each area was the outcome of interest and was modelled using a trivariate logistic regression model, and incorporated random effects to measure spatial correlation. Results The risk of fever was positively associated with high and medium malaria endemicity levels relative to low endemicity level, while for diarrhoea and pneumonia we observed marginal positive association at high endemicity level relative to low endemicity level, controlling for confounding covariates and heterogeneity. A positive spatial correlation was found between fever and diarrhoea (r = 0.29); while weak associations were estimated between fever and pneumonia (r = 0.01); and between diarrhoea and pneumonia (r = 0.05). The proportion of structured spatial variation compared to unstructured variation was 0.67 (95% credible interval (CI): 0.31–0.91) for fever, 0.67 (95 % CI: 0.27–0.93) for diarrhoea, and 0.87 (95% CI: 0.62–0.96) for pneumonia. Conclusion The analysis suggests some similarities in subdistrict-specific spatial variation of childhood morbidities of fever, diarrhoea and pneumonia, and might be a result of shared and overlapping risk factors, one of which is malaria endemicity.
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Affiliation(s)
- Lawrence N Kazembe
- Applied Statistics and Epidemiology Research Unit, Mathematical Sciences Department, Chancellor College, University of Malawi, Zomba, Malawi
- Malaria Research Programme, Medical Research Council, Durban, South Africa
| | - Adamson S Muula
- Department of Community Health, College of Medicine, University of Malawi, Blantyre, Malawi
| | - Christopher C Appleton
- School of Biological and Conservation Sciences, University of KwaZulu-Natal, Durban, South Africa
| | - Immo Kleinschmidt
- Infectious Diseases Epidemiology Unit, Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, UK
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278
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Lama J, Planelles V. Host factors influencing susceptibility to HIV infection and AIDS progression. Retrovirology 2007; 4:52. [PMID: 17651505 PMCID: PMC1978541 DOI: 10.1186/1742-4690-4-52] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2007] [Accepted: 07/25/2007] [Indexed: 12/21/2022] Open
Abstract
Transmission of HIV first results in an acute infection, followed by an apparently asymptomatic period that averages ten years. In the absence of antiretroviral treatment, most patients progress into a generalized immune dysfunction that culminates in death. The length of the asymptomatic period varies, and in rare cases infected individuals never progress to AIDS. Other individuals whose behavioral traits put them at high-risk of HIV transmission, surprisingly appear resistant and never succumb to infection. These unique cases highlight the fact that susceptibility to HIV infection and progression to disease are complex traits modulated by environmental and genetic factors. Recent evidence has indicated that natural variations in host genes can influence the outcome of HIV infection and its transmission. In this review we summarize the available literature on the roles of cellular factors and their genetic variation in modulating HIV infection and disease progression.
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Affiliation(s)
- Juan Lama
- La Jolla Institute for Molecular Medicine, 4570 Executive Drive, Suite 100, San Diego, California 92121, USA
- RetroVirox, Inc. 4570 Executive Drive, Suite 100, San Diego, California 92121, USA
| | - Vicente Planelles
- Department of Pathology, University of Utah School of Medicine, 15 North Medical Drive East #2100 – Room 2520, Salt Lake City, Utah 84112, USA
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279
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Graham AL, Cattadori IM, Lloyd-Smith JO, Ferrari MJ, Bjørnstad ON. Transmission consequences of coinfection: cytokines writ large? Trends Parasitol 2007; 23:284-91. [PMID: 17466597 DOI: 10.1016/j.pt.2007.04.005] [Citation(s) in RCA: 94] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Coinfection of a host by multiple parasite species is commonly observed and recent epidemiological work indicates that coinfection can enhance parasite transmission. This article proposes an immunoepidemiological framework to understand how within-host interactions during coinfection might affect between-host transmission. Cytokines, immune signalling molecules with a fundamental role in the amplification of antiparasitic effector mechanisms, provide a useful way to simplify immunological complexity for this endeavour--focusing on cytokines offers analytical tractability without sacrificing realism. Testable predictions about the epidemiological consequences of coinfection are generated by this conceptual framework.
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Affiliation(s)
- Andrea L Graham
- Institutes of Evolution, Immunology & Infection Research, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
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280
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Flanagan JF, Blus BJ, Kim D, Clines KL, Rastinejad F, Khorasanizadeh S. Molecular implications of evolutionary differences in CHD double chromodomains. J Mol Biol 2007; 369:334-42. [PMID: 17433364 PMCID: PMC1948097 DOI: 10.1016/j.jmb.2007.03.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2007] [Accepted: 03/09/2007] [Indexed: 11/16/2022]
Abstract
Double chromodomains occur in CHD proteins, which are ATP-dependent chromatin remodeling factors implicated in RNA polymerase II transcription regulation. Biochemical studies suggest important differences in the histone H3 tail binding of different CHD chromodomains. In human and Drosophila, CHD1 double chromodomains bind lysine 4-methylated histone H3 tail, which is a hallmark of transcriptionally active chromatin in all eukaryotes. Here, we present the crystal structure of the yeast CHD1 double chromodomains, and pinpoint their differences with that of the human CHD1 double chromodomains. The most conserved residues in these double chromodomains are the two chromoboxes that orient adjacently. Only a subset of CHD chromoboxes can form an aromatic cage for methyllysine binding, and methyllysine binding requires correctly oriented inserts. These factors preclude yeast CHD1 double chromodomains from interacting with the histone H3 tail. Despite great sequence similarity between the human CHD1 and CHD2 chromodomains, variation within an insert likely prevents CHD2 double chromodomains from binding lysine 4-methylated histone H3 tail as efficiently as in CHD1. By using the available structural and biochemical data we highlight the evolutionary specialization of CHD double chromodomains, and provide insights about their targeting capacities.
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Affiliation(s)
- John F Flanagan
- Department of Biochemistry and Molecular Genetics, University of Virginia Health System, Charlottesville, VA 22908, USA
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