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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Toxoplasma gondii in Australian Marsupials

Nevi.Parameswaran@gmail.com, Nivethitha (Nevi) Parameswaran January 2008 (has links)
Diagnostic tools were developed and utilised to detect Toxoplasma gondii infection in a range of Australian marsupial species and identify epidemiological trends. An ELISA was developed to detect anti-T. gondii IgG in macropod marsupials. When compared with the commercially available MAT (modified agglutination test), the ELISA was in high agreement and yielded a ê coefficient of 0.96. Of 18 western grey kangaroos (Macropus fuliginosus) tested for the presence of T. gondii DNA by PCR, the 9 ELISA positive kangaroos tested PCR positive and the 9 ELISA negative kangaroos tested PCR negative indicating that the ELISA protocol was both highly specific and sensitive and correlated 100% with the more labour intensive PCR assay. A T. gondii seroprevalence study was undertaken on free ranging Australian marsupials. There was a T. gondii seroprevalence of 15.5% (95%CI: 10.7-20.3) in western grey kangaroos located in the Perth metropolitan area. The T. gondii seroprevalence in male western grey kangaroos was significantly less than their female counterparts (p=0.038), which may be related to behavioural differences causing differences in exposure to oocysts or recrudescence of T. gondii infection in pregnant females. Marsupial populations located in islands free from felids had a low overall T. gondii seroprevalence. A case control study determined that marsupials located in areas where felids may roam are 14.20 (95%CI: 1.94-103.66) times more likely to be T. gondii seropositive than marsupials located on felid-free islands. PCR, immunohistochemistry and serological techniques were used to detect T. gondii infection in marsupial dams and their offspring. T. gondii DNA was detected in the pouch young of chronically infected western grey kangaroos and a woylie (Bettongia penicillata). T. gondii DNA was also identified in the mammary gland of the woylie dam suggesting that infection of the woylie pouch young was from suckling milk from the mammary gland. Results of the study demonstrate that vertical transmission of T. gondii occurs in Australian marsupials and may be of importance in the maintenance of T. gondii infection in Australian marsupial populations. Animal tissue and meat from Australia, predominately from Australian marsupials, were screened for T. gondii DNA using PCR primers for the multi-copy, T. gondii specific B1 gene. Sequencing of the B1 gene revealed atypical genotypes in 7 out of 13 samples from Australia. These 7 isolates contained single nucleotide polymorphisms (SNPs) in the B1 gene that could not be matched with known sequences from strains I, II, III and X. Six unique genotypes were identified out of the 7 atypical isolates; two out of the 7 isolates had the same unique sequence at the B1 gene whereas the other 5 isolates each had different combinations of SNPs at the B1 gene. A majority of T. gondii isolates sampled from native Australian marsupials were of an atypical genotype. The discovery of atypical strains of T. gondii in Australia leads to further questions regarding the origin and transmission of these atypical strains. Additional studies linking atypical strains with their clinical manifestation are also warranted.
2

Prophylaxie de l'Hépatite a Virus B en Début d'Enfance -Immunoglobulines Spécifiques Anti-HBs (HBIG)

ITOH, SHIGEMITSU, TSUYUKI, MASUMI, MINOWA, SHIGERU, TSUZUKI, KAZUO, NOGUCHI, HIROMICHI, TANABE, MINORU 03 1900 (has links)
No description available.
3

Iniciação sexual de mulheres jovens vivendo com HIV/Aids no município de São Paulo / Sexual Initiation of young women living with HIV/Aids in the city of São Paulo

Raquel Zanelatto Alves da Silva 15 December 2017 (has links)
Esta dissertação teve como objetivo examinar especificidades no processo de iniciação sexual de jovens mulheres vivendo com HIV. Utilizaram-se dados do estudo transversal GENIH: gênero e infecção pelo HIV, com amostra probabilística, que entrevistou mulheres de 18 a 49 anos, usuárias dos serviços públicos de saúde no município de São Paulo. Analisaram-se variáveis referentes às características sociodemográficas, à primeira relação sexual e às trajetórias reprodutivas das jovens de 18 a 24 anos: 130 mulheres vivendo com HIV/Aids (MVHA) e 257 mulheres não vivendo com HIV/Aids (MNVHA). As MVHA foram estratificadas em infectadas por transmissão vertical (TV) e infectadas por outras vias (OV). Observou-se associação (p<0,05) entre iniciação sexual tardia e ser infectada por TV, possuir religião, ter cursado ensino médio completo ou mais e não ter feito uso de drogas na vida. As jovens infectadas por outras vias iniciaram-se mais cedo do que as demais, com parceiros bem mais velhos e relataram menor uso de preservativo na primeira relação sexual. Há diferenças significativas entre os grupos com relação ao tempo de vida sexual ativa, conjugalidade, número de gestações e aborto. Apesar de mais tardias, jovens infectadas por transmissão vertical (TV) apresentaram menor intervalo entre a primeira relação sexual e a primeira gravidez do que as demais, logo o adiamento do início da vida sexual não implica na postergação da trajetória reprodutiva. A multiplicidade de trajetórias sexuais e reprodutivas evidencia a diversidade de intercâmbios entre as experiências de socialização que se dão no âmbito da escola, família, trabalho e demais instituições a que as jovens pertencem. O processo de iniciação sexual das jovens vivendo com HIV carrega marcas das hierarquias de gênero que modulam a socialização juvenil / The present dissertation aimed at examining the specificities of the sexual initiation process of young women living with HIV. Data from the cross-sectional study called GENIH: Gender and HIV infection were used. A probabilistic sample included interviewing women aged 18-49, who were users of the public health services in the city of São Paulo. Variables relating to sociodemographic characteristics, first sexual intercourse, and reproductive trajectories of young women aged 18-24 130 women living with HIV (WLHIV) and 257 not living with HIV (WNLHIV) were analysed. The WLHIV were stratified either by vertical transmission infection (VT) or by other routes infection (OR). Association (p<0,05) between late sexual initiation and getting infected by (VT), having a religion, having attended high school or college, not having used drugs was noticed. Young women who got infected by other routes had an earlier initiation than the others, with significantly older partners, and reported less frequent use of condoms in the first sexual intercourse. There are significant differences between the groups concerning active sexual life length, conjugality, number of pregnancies and abortions. Though having a later initiation, young women infected by VT reported shorter time span between the first sexual intercourse and the first pregnancy than the others. Therefore the postponement of the sexual initiation does not imply in postponing the reproductive trajectory. The multiplicity of sexual and reproductive trajectories shows the diversity of interchanges among socializing experiences that take place in the context of school, family, work place and other institutions to which the young women belong. The process of sexual initiation of young women living with HIV is marked by the gender hierarchy that shapes the youth socialization
4

Estudo evolutivo das crianças expostas ao HIV e notificadas pelo núcleo de vigilância epidemiológica do HCFMRP-USP / Evolutive study of children exposed to HIV and notified by the Nucleus of Epidemiological Surveillance of HCFMRP-USP

Adriana Nunes Fernandes da Silva 23 December 2004 (has links)
Esta pesquisa teve como objetivo avaliar a evolução de crianças nascidas de mães positivas para o HIV ou com AIDS no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, durante o período compreendido entre 1986 e 2001. Foram levantadas informações relativas a profilaxia pré-natal e da criança ao nascer, assim como à reversão sorológica, soropositividade e sobrevida. Dos 680 participantes, 67 (9,8%) se infectaram, 520 (76,5%) não se infectaram e 93 (13,7%) ficaram sem informação devido ao abandono de seguimento. Profilaxia durante a gestação ocorreu em 144 mulheres com o uso de uma droga (21,2%) e em 77 com a utilização de duas ou mais drogas (11,3%), não tendo se verificado em 459 gestantes (67,5%). Entre os recém nascidos, 205 (30,1%) receberam apenas AZT, 134 (19,7%) foram medicados com AZT+SMX/TMP e 341 (50,1%) não foram tratados. Ocorreu óbito de 39 crianças (5,7%), com 559 (82,2%) tendo permanecido vivas e 82 (12,0%) cuja informação foi perdida. O percentual de óbito foi consideravelmente mais elevado entre os que não receberam profilaxia (9,7%), em relação aos que receberam apenas AZT (2,9%). Não se verificou nenhuma morte entre as 134 crianças em uso AZT+SMX/TMP. As proporções de óbitos variaram de acordo com o tempo, atingindo 9,5% no período pré-profilaxia (1986/1995) e caindo para 2,7% entre os anos de 1996 e 2001. Entre os 67 indivíduos infectados pelo HIV foram verificadas 22 mortes (33,8%), valor muito superior ao encontrado entre os 520 não infectados, nos quais ocorreram apenas 4 óbitos (0,8%). Os tempos medianos de reversão sorológica foram iguais a 589 dias para os nascidos de 1986 a 1995, e 451 dias, para os que nasceram no período 1996 a 2001. As curvas de sobrevivência demonstraram o evidente favorecimento dos indivíduos que foram submetidos a algum tipo de profilaxia, indicando que a intervenção terapêutica trouxe ganhos inquestionáveis para os recém nascidos de gestantes positivas para o HIV ou com AIDS. / The objective of the present study was to evaluate the evolution of children born to HIV-positive mothers or mothers with AIDS at the University Hospital, Faculty of Medicine of Ribeirão Preto, during the period from 1986 to 2001. Information was obtained about prenatal prophylaxis and infant prophylaxis at birth, and about serologic reversal, seropositivity and survival. Of the 680 participants, 67 (9.8%) were infected, 520 (76.5%) were not infected, and no information was available for 93 (13.7%) infants who were lost to follow-up. Prophylaxis during pregnancy occurred in 144 women with the use of mono prophylaxis (21.2%) and in 77 with the use of two or more drugs (11.3%), and 459 (67.5%) received no prophylaxis. Among the newborns, 205 (30.1%) received only AZT, 134 (19.7%) were medicated with AZT+SMX/TMP, and 341 (50.1%) had not carried trough prophylaxis. Thirty-nine children died (5.7%), 559 (82.2%) continued to live, and for 82 (120%) the information was lost. The death rate was considerably more elevated among the children who did not receive prophylaxis (9.7%) compared to those who received only AZT (2.9%). No death occurred among the 134 children had prophylaxis with AZT+SMX/TMP. Death rates varied according to time, reaching 9.5% during the preprophylaxis period (1986/1995) and falling to 2.7% between 1996 and 2001 Twenty-two deaths occurred among the 67 HIV-infected individuals (33.8%), a much higher value than detected among the 520 non-infected individuals (4 deaths, 0.8%). The median times for serological reversal were 589 days for the infants born between 1986 and 1995 and 451 days for those born from 1996 to 2001. The survival curves demonstrated an evident favoring of individuals submitted to some type of prophylaxis, indicating that therapeutic intervention has brought unquestionable gains for infants born to HIV-positive mothers or mothers with AIDS.
5

Estudo evolutivo das crianças expostas ao HIV e notificadas pelo núcleo de vigilância epidemiológica do HCFMRP-USP / Evolutive study of children exposed to HIV and notified by the Nucleus of Epidemiological Surveillance of HCFMRP-USP

Silva, Adriana Nunes Fernandes da 23 December 2004 (has links)
Esta pesquisa teve como objetivo avaliar a evolução de crianças nascidas de mães positivas para o HIV ou com AIDS no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto, durante o período compreendido entre 1986 e 2001. Foram levantadas informações relativas a profilaxia pré-natal e da criança ao nascer, assim como à reversão sorológica, soropositividade e sobrevida. Dos 680 participantes, 67 (9,8%) se infectaram, 520 (76,5%) não se infectaram e 93 (13,7%) ficaram sem informação devido ao abandono de seguimento. Profilaxia durante a gestação ocorreu em 144 mulheres com o uso de uma droga (21,2%) e em 77 com a utilização de duas ou mais drogas (11,3%), não tendo se verificado em 459 gestantes (67,5%). Entre os recém nascidos, 205 (30,1%) receberam apenas AZT, 134 (19,7%) foram medicados com AZT+SMX/TMP e 341 (50,1%) não foram tratados. Ocorreu óbito de 39 crianças (5,7%), com 559 (82,2%) tendo permanecido vivas e 82 (12,0%) cuja informação foi perdida. O percentual de óbito foi consideravelmente mais elevado entre os que não receberam profilaxia (9,7%), em relação aos que receberam apenas AZT (2,9%). Não se verificou nenhuma morte entre as 134 crianças em uso AZT+SMX/TMP. As proporções de óbitos variaram de acordo com o tempo, atingindo 9,5% no período pré-profilaxia (1986/1995) e caindo para 2,7% entre os anos de 1996 e 2001. Entre os 67 indivíduos infectados pelo HIV foram verificadas 22 mortes (33,8%), valor muito superior ao encontrado entre os 520 não infectados, nos quais ocorreram apenas 4 óbitos (0,8%). Os tempos medianos de reversão sorológica foram iguais a 589 dias para os nascidos de 1986 a 1995, e 451 dias, para os que nasceram no período 1996 a 2001. As curvas de sobrevivência demonstraram o evidente favorecimento dos indivíduos que foram submetidos a algum tipo de profilaxia, indicando que a intervenção terapêutica trouxe ganhos inquestionáveis para os recém nascidos de gestantes positivas para o HIV ou com AIDS. / The objective of the present study was to evaluate the evolution of children born to HIV-positive mothers or mothers with AIDS at the University Hospital, Faculty of Medicine of Ribeirão Preto, during the period from 1986 to 2001. Information was obtained about prenatal prophylaxis and infant prophylaxis at birth, and about serologic reversal, seropositivity and survival. Of the 680 participants, 67 (9.8%) were infected, 520 (76.5%) were not infected, and no information was available for 93 (13.7%) infants who were lost to follow-up. Prophylaxis during pregnancy occurred in 144 women with the use of mono prophylaxis (21.2%) and in 77 with the use of two or more drugs (11.3%), and 459 (67.5%) received no prophylaxis. Among the newborns, 205 (30.1%) received only AZT, 134 (19.7%) were medicated with AZT+SMX/TMP, and 341 (50.1%) had not carried trough prophylaxis. Thirty-nine children died (5.7%), 559 (82.2%) continued to live, and for 82 (120%) the information was lost. The death rate was considerably more elevated among the children who did not receive prophylaxis (9.7%) compared to those who received only AZT (2.9%). No death occurred among the 134 children had prophylaxis with AZT+SMX/TMP. Death rates varied according to time, reaching 9.5% during the preprophylaxis period (1986/1995) and falling to 2.7% between 1996 and 2001 Twenty-two deaths occurred among the 67 HIV-infected individuals (33.8%), a much higher value than detected among the 520 non-infected individuals (4 deaths, 0.8%). The median times for serological reversal were 589 days for the infants born between 1986 and 1995 and 451 days for those born from 1996 to 2001. The survival curves demonstrated an evident favoring of individuals submitted to some type of prophylaxis, indicating that therapeutic intervention has brought unquestionable gains for infants born to HIV-positive mothers or mothers with AIDS.
6

Iniciação sexual de mulheres jovens vivendo com HIV/Aids no município de São Paulo / Sexual Initiation of young women living with HIV/Aids in the city of São Paulo

Silva, Raquel Zanelatto Alves da 15 December 2017 (has links)
Esta dissertação teve como objetivo examinar especificidades no processo de iniciação sexual de jovens mulheres vivendo com HIV. Utilizaram-se dados do estudo transversal GENIH: gênero e infecção pelo HIV, com amostra probabilística, que entrevistou mulheres de 18 a 49 anos, usuárias dos serviços públicos de saúde no município de São Paulo. Analisaram-se variáveis referentes às características sociodemográficas, à primeira relação sexual e às trajetórias reprodutivas das jovens de 18 a 24 anos: 130 mulheres vivendo com HIV/Aids (MVHA) e 257 mulheres não vivendo com HIV/Aids (MNVHA). As MVHA foram estratificadas em infectadas por transmissão vertical (TV) e infectadas por outras vias (OV). Observou-se associação (p<0,05) entre iniciação sexual tardia e ser infectada por TV, possuir religião, ter cursado ensino médio completo ou mais e não ter feito uso de drogas na vida. As jovens infectadas por outras vias iniciaram-se mais cedo do que as demais, com parceiros bem mais velhos e relataram menor uso de preservativo na primeira relação sexual. Há diferenças significativas entre os grupos com relação ao tempo de vida sexual ativa, conjugalidade, número de gestações e aborto. Apesar de mais tardias, jovens infectadas por transmissão vertical (TV) apresentaram menor intervalo entre a primeira relação sexual e a primeira gravidez do que as demais, logo o adiamento do início da vida sexual não implica na postergação da trajetória reprodutiva. A multiplicidade de trajetórias sexuais e reprodutivas evidencia a diversidade de intercâmbios entre as experiências de socialização que se dão no âmbito da escola, família, trabalho e demais instituições a que as jovens pertencem. O processo de iniciação sexual das jovens vivendo com HIV carrega marcas das hierarquias de gênero que modulam a socialização juvenil / The present dissertation aimed at examining the specificities of the sexual initiation process of young women living with HIV. Data from the cross-sectional study called GENIH: Gender and HIV infection were used. A probabilistic sample included interviewing women aged 18-49, who were users of the public health services in the city of São Paulo. Variables relating to sociodemographic characteristics, first sexual intercourse, and reproductive trajectories of young women aged 18-24 130 women living with HIV (WLHIV) and 257 not living with HIV (WNLHIV) were analysed. The WLHIV were stratified either by vertical transmission infection (VT) or by other routes infection (OR). Association (p<0,05) between late sexual initiation and getting infected by (VT), having a religion, having attended high school or college, not having used drugs was noticed. Young women who got infected by other routes had an earlier initiation than the others, with significantly older partners, and reported less frequent use of condoms in the first sexual intercourse. There are significant differences between the groups concerning active sexual life length, conjugality, number of pregnancies and abortions. Though having a later initiation, young women infected by VT reported shorter time span between the first sexual intercourse and the first pregnancy than the others. Therefore the postponement of the sexual initiation does not imply in postponing the reproductive trajectory. The multiplicity of sexual and reproductive trajectories shows the diversity of interchanges among socializing experiences that take place in the context of school, family, work place and other institutions to which the young women belong. The process of sexual initiation of young women living with HIV is marked by the gender hierarchy that shapes the youth socialization
7

Parasites of Feral Cats and Native Fauna from Western Australia: The Application of Molecular Techniques for the Study of Parasitic Infections in Australian Wildlife

Padams@central.murdoch.edu.au, Peter John Adams January 2003 (has links)
A survey of gastro-intestinal parasites was conducted on faecal samples collected from 379 feral cats and 851 native fauna from 16 locations throughout Western Australia. The prevalence of each parasite species detected varied depending upon the sampling location. Common helminth parasites detected in feral cats included Ancylostoma spp. (29.8%), Oncicola pomatostomi (25.6%), Spirometra erinaceieuropaei (14%), Taenia taeniaeformis (4.7%), Physaloptera praeputialis (3.7%) and Toxocara cati (2.6%). The most common protozoan parasites detected in feral cats were Isospora rivolta (16.9%) and I. felis (4.5%). The native mammals were predominately infected with unidentified nematodes of the order Strongylida (59.1%), with members of the orders Rhabditida, Spirurida and Oxyurida also common. Oxyuroid nematodes were most common in the rodents (47.9%) and western grey kangaroos (27.8%). Several species of Eimeria were detected in the marsupials whilst unidentified species of Entamoeba and coccidia were common in most of the native fauna. Primers anchored in the first and second internal transcribed spacers (ITS1 and ITS2) of the ribosomal DNA (rDNA) were used to develop a polymerase chain reaction-linked restriction fragment length polymorphism (PCR-RFLP) technique to differentiate the species of Ancylostoma detected in feral cats. Amplification of the ITS+ region (ITS1, ITS2 and 5.8S gene) followed by digestion with the endonuclease RsaI produced characteristic patterns for A. tubaeforme, A. ceylanicum and A. caninum, which were detected in 26.6%, 4.7% and 0% of feral cats respectively. Giardia was detected in a cat, dingo, quenda and two native rodents. Sequence analysis at the small subunit rDNA gene (SSU-rDNA) identified the cat and dingo as harbouring G.duodenalis infections belonging to the genetic assemblages A and D respectively. Subsequent analysis of the SSU-rDNA and elongation factor 1 alpha (ef1á) identified a novel species of Giardia occurring in the quenda. Attempts to genetically characterise the Giardia in the two native rodents were unsuccessful. Serological detection of Toxoplasma gondii was compared to a one tube hemi-nested PCR protocol to evaluate its sensitivity. PCR was comparable to serology in detecting T. gondii infections, although PCR was a much more definitive and robust technique than serology for large numbers of samples. Amplification of T. gondii DNA detected infections in 4.9% of feral cats and 6.5% of native mammals. The distribution of T. gondii does not appear to be restricted by environmental factors, which implies that vertical transmission is important for the persistence of T. gondii infections in Western Australia. These results demonstrate that cats carry a wide range of parasitic organisms, many of which may influence the survival and reproduction of native mammals. As such, the large-scale conservation and reintroduction of native fauna in Western Australia must not disregard the potential influence parasites can have on these populations.
8

The Impact of GB Virus C co-infection on Mother to Child transmission of Human Immunodeficiency Virus

Bhanich Supapol, Wendy C. 03 March 2010 (has links)
GB virus C (GBV-C) is a common, apathogenic virus that can inhibit human immunodeficiency virus (HIV) replication in vitro. Persistent coinfection with GBV-C has been associated with improved survival among HIV-infected adults while loss of GBV-C viremia has been associated with poor survival. If GBV-C does inhibit HIV replication, it is possible that GBV-C infection may reduce mother-to-child-transmission (MTCT) of HIV. This study investigated whether maternal or infant GBV-C infection was associated with reduced MTCT of HIV infection. The study population consisted of 1,783 pregnant women from three Bangkok perinatal HIV transmission studies (1992-94, 1996-7, 1999-2004). We tested plasma collected at delivery for GBV-C RNA, GBV-C antibody, and GBV-C viral genotype. If maternal GBV-C RNA was detected, the four- or six-month infant specimen was tested for GBV-C RNA. Rates of MTCT of HIV in GBV-C-infected and GBV-C-uninfected women and infants were compared using multiple logistic regression as were associations with MTCT of GBV-C and prevalence of GBV-C infection. The prevalence of GBV-C infection (i.e. presence of RNA or antibody) was 33% among HIV-infected women and 15% among HIV-uninfected women. Forty-one percent of GBV-C-RNA-positive women transmitted GBV-C to their infants. Only two of 101 (2.0%) GBV-C-RNA-positive infants acquired HIV infection compared to 162 (13.2%) of 1,232 of GBV-C-RNA-negative infants (RR 0.15, p<0.0001). This association remained after adjustment for maternal HIV viral load, antiretroviral prophylaxis, CD4+ count and other covariates. MTCT of HIV was not associated with presence of maternal GBV-C RNA or maternal GBV-C antibody. Maternal receipt of antiretroviral therapy was associated with increased MTCT of GBV-C, as was high GBV-C viral load, vaginal delivery and absence of infant HIV infection. GBV-C infection among women was independently associated with more than one lifetime sexual partner, intravenous drug use and HIV-infection. We observed a higher prevalence of GBV-C infection among HIV-infected compared to HIV-uninfected pregnant women in Thailand, likely due to common risk factors. Antiretroviral therapy appears to increase MTCT of GBV-C. Infant GBV-C acquisition, but not maternal GBV-C infection, was significantly associated with reduced MTCT of HIV. Mechanisms for these later two associations are unknown. / Bhanich Supapol W, Remis RS, Raboud J, Millson M, Tappero J, Kaul R, Kulkarni P, McConnell MS, Mock PA, Culnane M, McNicholl J, Roongpisuthipong A, Chotpitayasunondh T, Shaffer N, Butera S. 2008. Reduced mother-to-child transmission of HIV associated with infant but not maternal GB virus C infection. J Infect Dis 197(10):1369-1377. Bhanich Supapol W, Remis RS, Raboud J, Millson M, Tappero JW, Kaul R, Kulkarni P, McConnell MS, Mock PA, McNicholl JM, Vanprarar N, Asavapiriayanont S, Shaffer N, Butera ST. 2009. Mother-to-child transmission of GB virus C in a cohort of women coinfected with GB virus C and HIV in Bangkok, Thailand. J Infect Dis 200:227-235.
9

The Impact of GB Virus C co-infection on Mother to Child transmission of Human Immunodeficiency Virus

Bhanich Supapol, Wendy C. 03 March 2010 (has links)
GB virus C (GBV-C) is a common, apathogenic virus that can inhibit human immunodeficiency virus (HIV) replication in vitro. Persistent coinfection with GBV-C has been associated with improved survival among HIV-infected adults while loss of GBV-C viremia has been associated with poor survival. If GBV-C does inhibit HIV replication, it is possible that GBV-C infection may reduce mother-to-child-transmission (MTCT) of HIV. This study investigated whether maternal or infant GBV-C infection was associated with reduced MTCT of HIV infection. The study population consisted of 1,783 pregnant women from three Bangkok perinatal HIV transmission studies (1992-94, 1996-7, 1999-2004). We tested plasma collected at delivery for GBV-C RNA, GBV-C antibody, and GBV-C viral genotype. If maternal GBV-C RNA was detected, the four- or six-month infant specimen was tested for GBV-C RNA. Rates of MTCT of HIV in GBV-C-infected and GBV-C-uninfected women and infants were compared using multiple logistic regression as were associations with MTCT of GBV-C and prevalence of GBV-C infection. The prevalence of GBV-C infection (i.e. presence of RNA or antibody) was 33% among HIV-infected women and 15% among HIV-uninfected women. Forty-one percent of GBV-C-RNA-positive women transmitted GBV-C to their infants. Only two of 101 (2.0%) GBV-C-RNA-positive infants acquired HIV infection compared to 162 (13.2%) of 1,232 of GBV-C-RNA-negative infants (RR 0.15, p<0.0001). This association remained after adjustment for maternal HIV viral load, antiretroviral prophylaxis, CD4+ count and other covariates. MTCT of HIV was not associated with presence of maternal GBV-C RNA or maternal GBV-C antibody. Maternal receipt of antiretroviral therapy was associated with increased MTCT of GBV-C, as was high GBV-C viral load, vaginal delivery and absence of infant HIV infection. GBV-C infection among women was independently associated with more than one lifetime sexual partner, intravenous drug use and HIV-infection. We observed a higher prevalence of GBV-C infection among HIV-infected compared to HIV-uninfected pregnant women in Thailand, likely due to common risk factors. Antiretroviral therapy appears to increase MTCT of GBV-C. Infant GBV-C acquisition, but not maternal GBV-C infection, was significantly associated with reduced MTCT of HIV. Mechanisms for these later two associations are unknown. / Bhanich Supapol W, Remis RS, Raboud J, Millson M, Tappero J, Kaul R, Kulkarni P, McConnell MS, Mock PA, Culnane M, McNicholl J, Roongpisuthipong A, Chotpitayasunondh T, Shaffer N, Butera S. 2008. Reduced mother-to-child transmission of HIV associated with infant but not maternal GB virus C infection. J Infect Dis 197(10):1369-1377. Bhanich Supapol W, Remis RS, Raboud J, Millson M, Tappero JW, Kaul R, Kulkarni P, McConnell MS, Mock PA, McNicholl JM, Vanprarar N, Asavapiriayanont S, Shaffer N, Butera ST. 2009. Mother-to-child transmission of GB virus C in a cohort of women coinfected with GB virus C and HIV in Bangkok, Thailand. J Infect Dis 200:227-235.
10

Interactions flavivirus-moustiques : diversité et transmission / Flavivirus-mosquito interactions : diversity and transmission

Lequime, Sébastian 21 June 2016 (has links)
Les flavivirus sont des virus à ARN parmi lesquels certains sont des arbovirus transmis entre hôtes vertébrés par des vecteurs arthropodes, notamment des moustiques. L'interaction avec les moustiques est centrale dans la biologie des flavivirus par son influence sur leur diversité génétique et transmission, mais certains de ses aspects restent méconnus. Au cœur de cette thèse, des approches basées sur les « big data », générées par des technologies modernes ou par compilation de travaux plus anciens, ont éclairé d’un jour nouveau la complexité des relations moustique-flavivirus. En explorant des génomes de moustiques anophèles, nous avons identifié et caractérisé des éléments viraux endogènes d'origine flavivirale chez Anopheles sinensis et An. minimus, suggérant l'existence de flavivirus infectant les anophèles et révélant une facette insoupçonnée de leur diversité. Par ailleurs, nous avons exploré, par séquençage haut-débit, la fine interaction entre le génotype du moustique Aedes aegypti et la diversité intra-hôte du virus de la dengue-1. Nos résultats montrent un fort effet de la dérive génétique lors de l'infection initiale, diminuant l'importance relative de la sélection naturelle, et une modulation de la diversité génétique intra-hôte du virus par le génotype du moustique. Enfin, nous avons compilé la littérature sur la transmission verticale des arbovirus chez les moustiques, c'est-à-dire de la femelle infectée à sa descendance, afin d'identifier des facteurs techniques et biologiques sous-jacents. Nos résultats améliorent la compréhension de ce mode de transmission et des stratégies employées par les arbovirus pour persister dans l’environnement. / Flaviviruses are RNA virus among which some are arboviruses transmitted between vertebrate hosts and arthropod vectors, like mosquitoes. The interaction with mosquitoes is key in the biology of flaviviruses because it influences their genetic diversity and transmission. However, some aspects however are still poorly understood. At the heart of the work presented in this dissertation, strategies based on ‘big data’, both by taking advantage of modern technologies and by compiling older literature, highlighted new aspects of the complex relationships between flaviviruses and mosquitoes. While exploring Anopheles mosquito genomes, we identified and characterized endogenous viral elements of flaviviral origin in Anopheles sinensis and An. minimus, which supports the existence of flaviviruses infecting Anopheles mosquitoes and highlights new aspected of their diversity. Besides, we explored, by deep sequencing, the fine-tuned interaction between genotypes of the mosquito Aedes aegypti and the intra-host diversity of dengue virus 1. Our results showed a strong effect of genetic drift during initial infection, reducing the relative importance of natural selection, and a modulation of the intra-host viral genetic diversity by the mosquito genotype. Finally, we assembled the litterature on arbovirus vertical transmission in the mosquito vector, i.e. from an infected female to her offspring, in order to identify underlying technical and biological predictors. Our results increase our understanding of this transmission mode and the strategies employed by arboviruses to persist in their environment.

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