Among people living with HIV (PLWH), adherence to antiretroviral therapy (ART) can be affected by problems of neurocognitive (NC) impairment, stress, alcohol and other drug (AOD) abuse, and other barriers. The aims of this research were to: (1) examine factors associated with NC impairment, (2) explore relationships between psychosocial variables with ART adherence and viral load (VL), and (3) evaluate the efficacy of an evidence-based intervention in improving ART adherence, increasing service utilization, and decreasing VL. The first study (n=370) was cross sectional and used structural equation modeling to test whether AOD use, years living with HIV, and time from HIV diagnosis to seeking care were associated with poorer NC functioning. The second study (n=246) used similar methods to test the hypothesis that stress, barriers to adherence, NC impairment, poor social support, and AOD use were related to lower VL mediated by ART adherence. The third study (n=243) evaluated an evidence-based, eight-session program to improve ART adherence, reduce VL, and increase service utilization in a randomized controlled trial. Study participants were PLWH living in South Florida, 18 to 60 years old, with a history of alcohol abuse enrolled from January 2009 through November 2012. Secondary analysis of available data showed: (1) scores on interference with executive functioning increased by 0.32 for each day of marijuana use and 1.18 for each year living with HIV, but no association was found between alcohol use and NC functioning; (2) each barrier to adherence was associated with a 10% decrease in adherence to ART and a 0.42 unit increase in VL (log10) and the relationship between barriers and VL was partially mediated by ART adherence; (3) participants in the evidence-based program were more likely than the comparison group to report an undetectable VL (OR=2.25, p Psychosocial factors affect VL, but ART adherence is essential in achieving an undetectable VL in PLWH.

Magister Public Health - MPH / Background: With the improvements in the effectiveness and availability of antiretroviral therapy (ART), perinatally infected children are surviving to adolescence and emerging as a significant sub-population living with HIV/AIDS in Zimbabwe. Adolescents, aged 10-19 years, face unique challenges related to adherence to chronic medication due to this period of vulnerability that is characterised by decreased parental support and supervision, decreased inhibition, increased risk-taking, and immature judgement. It is widely reported that poor adherence to ART leads to viral rebound, disease progression and drug resistance, in addition to increasing the risk of transmitting resistant strains of HIV to others. It is imperative to determine the factors that influence ART adherence among HIV positive adolescents so that effective interventions can be put in place. The current study described the factors that are associated with adherence to ART among HIV positive adolescents in Zimbabwe. Methodology: A cross-sectional survey of 136 randomly selected adolescents (10-19 years) who were receiving ART at two referral hospitals in Masvingo District in 2019 was undertaken. A questionnaire was administered to collect data on socio-demographic characteristics, adherence and factors related to adherence such as person/patient, health system, medication, disease characteristics and social factors. Clinical data were extracted from the Electronic Monitoring Patient System. SPSS v24 was used for descriptive and inferential analysis. Results: More than half of the participants (61%) had combined optimal adherence (dose adherence, schedule adherence and adhered to dietary instructions) in the previous three days. The most frequent reasons reported for missing HIV medications in the previous month was being away from home (50%); forgetfulness (25%); and having too many pills to take (25%). In bivariate analysis, only duration of time since HIV diagnosis was significantly associated with combined adherence to ART in the previous three days. Conclusion: Tailored interventions are recommended to address low adherence amongst adolescents. These interventions should include convenient clinic appointment schedules for adolescents to pick up medication, reminders to take medication, regimen change to a single dose, and peer education and adherence clubs to improve knowledge about HIV and treatment, and curb treatment fatigue.

Although nucleic acid tests (NATs) for human immunodeficiency virus (HIV) exhibit many advantages, such as early detection and viral load quantification, over immunological assays, their widespread use is limited by their demand for high-level infrastructure, sophisticated equipment, and advanced staff competence. Furthermore, when quantifying viral loads of patients, it has been reported that these assays can underestimate viral quantities by 22- to 100-fold due to primer-template mismatches in more divergent HIV subtypes. Therefore, we have developed a cost-effective and sequence-independent assay for the detection and quantification of HIV utilizing a modified nucleic acid sequence-based amplification (NASBA) protocol coupled to an electrochemical DNA biosensor. The modified NASBA reaction involves the addition of a 22-nucleotide tag between the T7 RNA Polymerase Promoter and the hybridizing region of the reverse primer. As a result, this tag will be placed at the 5' end of each amplicon regardless of the target sequence. We then designed the DNA sensor to hybridize to this segment of the amplicon specifically. Therefore, hybridization, and subsequently, detection, is dependent only on the presence of this tag and not the viral RNA sequence itself. As a result, the issue of underestimating viral loads is eliminated as multiple primers can be used in one reaction without having to use multiple sensors. The use of an isothermal NASBA technique and a reusable gold-disc electrode for the sensor helps drive down the cost of the assay by eliminating the need for thermocyclers and fluorometers used by conventional NATs.

<p>Human rhinovirus (HRV) is a single-stranded RNA virus responsible for causing the common cold and exacerbating chronic respiratory diseases. HRV is the most common cause of acute respiratory illness. Unfortunately, difficult culturing conditions and perceived mild symptoms have limited our understanding of HRV. This thesis characterizes fundamental aspects of HRV such as viral load in different patient populations, prevalence and diversity of HRV, and severity and duration of infection.</p> <p>We developed an HRV qPCR assay to quantitate HRV in clinical isolates. We used this assay to measure viral loads in hospitalized and community members. We found that HRV viral loads were similar regardless of age and need for hospitalization. Viral loads were significantly lower amongst individuals with asymptomatic HRV infection than symptomatic HRV infection. Next, we determined the prevalence and diversity of HRV in children and adults. We found that HRV is the most common respiratory pathogen in September-October in both children and adults. A broad range of HRV genotypes can be found circulating amongst children and adults; however HRV C is more prevalent in children. Furthermore, we investigated the association of HRV C duration and severity of illness. Among otherwise healthy individuals, HRV C did not persist longer than HRV A/B, nor was the viral load significantly different. In hospitalized children, HRV C was not more associated with an asthma or wheeze diagnosis. Overall, our data suggest that viral loads do not predict the severity of illness, HRV C commonly occurs in children, and behaves like other HRV species.</p> / Master of Science (MSc)

Between 1994 to 1998 the ANRS 049a DITRAME trial was conducted during which a short regimen of ZDV demonstrated for the first time acceptability, tolerance and efficacy on reduction of mother-to-child transmission (MTCT). Our major aim was to analyze certain virological characteristics of infected women in this cohort and their association to HIV-1 transmission. On the one hand, we analyzed the HIV-1 replication capacity in different physiological compartments : blood, vaginal fluids (VF) and breast milk (BM) related to MTCT were investigated by nested case control studies in the DITRAME cohort. We demonstrated the relationship between plasma viral load (VL), at 34 weeks of amenorrheae and at Day 8 post partum, and MTCT in Africa where the probability to be exclusively breastfed for an one year infant is 46.6%. We also analyzed relationship between plasma VL and ZDV treatment. Additionally, we demonstrated that MTCT is essentially the consequence of a high proviral load in VF in our context. Moreover, reduced levels of HIV-1 RNA in milk at Day 8 were observed in mothers receiving ZDV therapy rather than in mothers under placebo. For the first time, the association between BMVL and postnatal transmission has been studied. We observed a highly significative difference between BMVL of women who transmitted the virus and those who did not. Moreover, univariate and multivariate analyzes clearly indicated that early breastfeeding log10 HIV-RNA at Day8 is an independent factor significatively associated to MTCT. Decreased median BMVL from 1608 copies/mL (c/ml) at Day8 to 346 c/ml at Day45 were found for mothers who transmitted the virus during the postpartum and who received placebo. Nevertheless, for those who received ZDV, median BMVL increased from 56 c/ml at Day8 to 470.5 c/ml at Day45. This marked trend to a rebound effect of BMVL could be the consequence of the treatment withdrawal as observed for adults at HAART withdrawal. On the other hand, we studied the variability of HIV and its association with MTCT. First, we analyzed HIV-1 diversity in African women in France and Burkina Faso. In a second step, we demonstrated that HMA was an adapted tool for co and super-infections studies for adults. By this way, we identified two superinfections among 147 women within our commercial sex workers cohort. Additionally, we used this tool to analyze children of the DITRAME cohort who were infected in utero and who could be superinfected during the delivery or later by breastfeeding. We identified seven children, among 18 who were infected in utero, displaying HMA profiles suspicions for co-infections, and who had a more important mortality rate than normally. Their proviral env sequences are currently analyzed. Moreover, we confirmed the fact that the rate of vitamin A has no influence on MTCT. De 1994 à 1998, s’est déroulé l’essai clinique DITRAME ANRS 049a qui a démontré, pour la première fois, l’acceptabilité, la tolérance et l’efficacité d’un traitement court de zidovudine (ZDV) sur la diminution de la TME. Notre travail s’est inscrit dans le cadre de cet essai et a eu pour but d’en analyser certains des aspects virologiques et leur rapport avec la transmission de la mère à l’enfant du VIH (TME). D’une part, nous avons analysé les niveaux de réplication virale dans différents compartiments physiologiques : le sang, les sécrétions cervico-vaginales (SCV) et le lait maternel (LM) et leur rapport avec la transmission, par des études cas-témoins nichées dans la cohorte DITRAME. Nous avons démontré le rapport entre la charge virale libre (CV) dans le plasma à 34 semaines d’aménorrhée et à J8 postpartum et la TME dans le contexte africain où la probabilité d’avoir un allaitement exclusif à un an est de 46,6%, et analysé leur rapport avec le traitement ZDV. Nous avons également démontré que la TME est essentiellement due à une charge provirale plus élevée dans les SCV dans notre contexte. De plus, grâce à la mise au point d’une technique, nous avons démontré que la ZDV avait un effet global marqué sur la diminution de la CV libre dans le LM. Il s’agit de la première étude mettant en relation la CV dans le lait avec la transmission postnatale. De même, nous avons observé une différence très hautement significative entre les charges virales libres des femmes ayant transmis le VIH et les non transmettrices. De plus, nos analyses univariée et multivariée démontrent que la CVlm mesurée en log10 de la lactation précoce (J8) est un facteur indépendant très significativement associé à la TME. Chez les femmes ayant transmis le virus durant le post-partum et non traitées à la ZDV, la CVlm médiane a décru de 1608 copies/mL (c/ml) à J8 à 346 c/ml à J45. Par contre, chez les femmes ayant transmis le virus mais ayant reçu un traitement ZDV, la CVlm médiane évolue de 56 c/ml à J8 à 470,5 c/ml à J45. Cette tendance marquée à un effet rebond de la CVlm à J45 laisse penser que la TME qui a lieu chez les femmes traitées à la ZDV pourrait être une conséquence de l’arrêt de ce traitement, comme observé chez les adultes après arrêt du traitement HAART. D’autre part, nous avons étudié la variabilité du VIH en fonction de la TME. Dans un premier temps, nous avons analysé la diversité du VIH-1 chez des mères africaines vivant en France, et par après au Burkina Faso. Ensuite, grâce à l’élaboration d’une nouvelle technique, nous avons démontré que le HMA pouvait être un outil adapté à l’étude des co- et sur-infection chez l’adulte. Nous avons identifié de cette manière deux surinfections parmi 147 femmes analysées au sein d’une cohorte de femmes à haut risque de surinfection. Nous avons ensuite utilisé ce moyen pour étudier des enfants de la cohorte DITRAME infectés in utero qui auraient pu se surinfecter durant le peripartum ou ensuite par l’allaitement. Sept enfants parmi 18 analysés, présentant des profils HMA à suspicion de coinfection et qui présentaient un taux de mortalité plus élevé que la normale, ont été identifiés. Leurs séquences provirales env sont en cours d’analyse actuellement. Par ailleurs, nous avons confirmé le fait que le taux de vitamine A n’a pas d’influence sur la TME.

Magister Public Health - MPH (Public Health) / Approximately 6% of all people living with HIV in 2016 are adolescents aged 10-19 years. It is reported globally that adolescents on antiretroviral therapy (ART) are at increased risk for poor retention in care, adherence and viral load suppression, compared to children and adults.

Submitted by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-26T10:51:28Z No. of bitstreams: 2 Dissertação - Thainara Calixto da Paz - 2016.pdf: 1536674 bytes, checksum: 9a527593418c3d06cd5b9029999ee4b3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2017-01-26T10:52:00Z (GMT) No. of bitstreams: 2 Dissertação - Thainara Calixto da Paz - 2016.pdf: 1536674 bytes, checksum: 9a527593418c3d06cd5b9029999ee4b3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2017-01-26T10:52:00Z (GMT). No. of bitstreams: 2 Dissertação - Thainara Calixto da Paz - 2016.pdf: 1536674 bytes, checksum: 9a527593418c3d06cd5b9029999ee4b3 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2016-12-05 / Human adenoviruses (HAdVs) may cause several clinical syndromes, and are a major cause of respiratory and acute gastroenteritis (AGE), especially among children. However, data on viral load, in more than one type clinical sample obtained from the same child, are still scarce. The aims of the present study were to evaluate the frequency of the HAdV, to determine the load viral in clinical samples, and to proceed molecular characterization of positive samples from children up to five years of age in association with symptomatology. For this, 200 children attended at Hospital Materno Infantil in Goiânia, Goiás; between March 2014 ad July 2015. One fecal and one nasopharyngeal swab sample was obtained from each child. The clinical samples (fecal and nasopharyngeal swabs) were submitted the DNA extraction by a commercial kit (Qiagen-Hilden, Alemanha), and screened by RT-qPCR (TaqMan) assay, with specific primers and probe targeting the hexon region of HAdV genome. The global frequency of HAdVs was 21% (42/200). Positivity in swabs was 9.5% (19/200), and in fecal samples 16% (32/200). Among the symptomatic children (n=129), 21% were positive in fecal samples (22/105) and 9.2% (10/108) in swab samples. Futhermore, 4.5% (9/200) were positive in both clinical samples. High viral loads were observed in both fecal and nasopharyngeal swab samples from symptomatic and asymptomatic children, and major positivity was found in symptomatic children with high load viral. High viral loads were observed in samples from symptomatic and asymptomatic children. Major positivity and load viral was found betwenn symptomatic children. HAdV types 3 of species B and 41 of HadV F species were detected. We hope that the data obtained can help in a better understanding of the pathogenesis of HAdV in children. / Os adenovírus humanos (HAdVs) são importantes agentes causadores de gastroenterite aguda e doença respiratória, principalmente entre as crianças menores de cinco anos de idade. Dados sobre a carga viral, em mais do que um tipo de amostra clínica obtida de um mesmo indivíduo durante a infecção, ainda são escassos. Os objetivos do presente estudo foram avaliar a frequência do HAdVs, determinar a carga viral em amostras clínicas, e proceder a caracterização molecular de amostras positivas de crianças até aos cinco anos de idade, em associação com a sintomatologia. Foram incluídas no estudo amostras de 200 crianças atendidas no Hospital Materno Infantil de Goiânia, Goiás; entre março de 2014 e julho de 2015. Uma amostra fecal e um swab nasofaringeano foram obtidos de cada criança. As amostras foram submetidas a extração, utilizando kit comercial (RNA mini-kit, Qiagen), e triadas por ensaio RT-qPCR (TaqMan, Life Technologies), com iniciadores e sonda específicos para a região codificadora do hexon. Foi observado índice global de positividade para HAdVs de 21% (42/200), o índice de positividade nas fezes foi 16% (32/200) e em swab foi de 9,5% (19/200). Entre as crianças sintomáticas (n=129), 21% foram positivas em amostras fecais (22/105) e 9,2% (10/108) em amostras de swabs. Ainda, 4,5% (9/200) foram positivas em ambas as amostras clínicas. Cargas virais elevadas foram observadas em amostras de crianças sintomáticas e assintomáticas, maior positividade foi encontrada em crianças sintomáticas com maiores cargas virais. Foram detectados HAdV tipos 3 da espécie B e 41 da espécie F de HadV. Esperamos que os dados obtidos possam auxiliar em um melhor entendimento da patogenia dos HAdV na população infantil.

Made available in DSpace on 2015-04-22T22:06:34Z (GMT). No. of bitstreams: 1 Norma Simone Santos da Costa.pdf: 922535 bytes, checksum: 30b2a80f13a50432465c6abc9e6f681a (MD5) Previous issue date: 2013-08-28 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Anemia is the most common hematologic complication in HIV-infected patients. Objective: To identify the clinical and sociodemographic as well as the presence of cytopenias and anemia in people living with HIV and AIDS (PLWHA) enrolled in the Reference Unit Specializing in Infectious Diseases Parasitic Pará State (URE-DIPE) within from 2005 to 2010. Methods: We conducted a descriptive epidemiological retrospective documentary type with a quantitative approach consisting of 111 individuals of both sexes aged 17-74 years in which we evaluated the frequency of anemia and other haematological disorders and their association with some features socioeconomic, demographic and clinical. Results: It was shown a male predominance (56%) with an average age close to 40 years with low educational level. Hematological changes were observed in immunocompetent patients: eritropenia (28.6%), thrombocytopenia (28%) and anemia (14%). And in immunocompromised patients: eritropenia (55.7%), thrombocytopenia (19.6%), anemia (42.3%). Leukopenia was observed in all patients. The most frequent symptom was asthenia. The viral load tended to decrease with the increase in CD4 + count. Conclusion: The demographic profile of people living with HIV / AIDS treated at URE-DIPE between the years 2005 and 2010 are male, with mean age of 40 years and low education level. There is the frequent presence of haematological disorders, with the highest prevalence of anemia, leukopenia and thrombocytopenia, a troubling information, since the occurrence of these was associated with low levels of CD4 + and symptoms of asthenia, weight loss and diarrhea in more advanced stages HIV infection. / a anemia é a complicação hematológica mais frequente em pacientes infectados pelo HIV. Objetivo: Identificar o perfil clínico e sociodemográfico, bem como a presença de citopenias e de anemia em pessoas vivendo com HIV e aids (PVHA) matriculadas na Unidade de Referência Especializada em Doenças Infecto Parasitárias do Estado do Pará (URE-DIPE) no período de 2005 a 2010. Métodos: Foi realizado um estudo epidemiológico descritivo tipo documental retrospectivo, com abordagem quantitativa composta por 111 indivíduos de ambos os sexos na faixa etária de 17 a 74 anos, no qual foi avaliada a frequência de anemia e outras alterações hematológicas e sua associação com algumas características socioeconômicas, demográficas e clínicas. Resultados: foi evidenciado um predomínio do sexo masculino (56%) com média de idade próxima aos 40 anos com baixo nível educacional. As alterações hematológicas observadas em pacientes imunocompetentes foram: eritropenia (28,6%), plaquetopenia (28%) e anemia (14%). E em pacientes imunodeprimidos: eritropenia (55,7%), plaquetopenia (19,6%), anemia (42,3%). A leucopenia foi observada em todos os pacientes avaliados. O sintoma mais frequente foi astenia. A carga viral apresentou tendência de decrescimento com o aumento da contagem de LTCD4+. Conclusão: O perfil sociodemográfico das pessoas vivendo com HIV/aids atendidos na URE-DIPE entre os anos de 2005 e 2010 é do sexo masculino, com idade média de 40 anos e baixo grau de instrução. Há a presença frequente de alterações hematológicas, com maior prevalência de anemia, leucopenia e plaquetopenia; uma informação preocupante, já que a ocorrência destas foi associada a baixos níveis de LTCD4+ e a presença de sintomas de astenia, perda de peso e diarreia nos estágios mais avançados da infecção pelo HIV.

Introdução: A AIDS (Síndrome da Imunodeficiência Adquirida) é caracterizada por uma disfunção grave no sistema imunológico causada por uma infecção por HIV (Human Immunodeficiency Virus). A quantificação da viremia (carga viral) é uma ferramenta muito útil no monitoramento dos pacientes infectados pelo HIV, sendo um marcador de progressão da doença e eficácia do tratamento. A estimativa incorreta da carga viral pode levar à decisão terapêutica equivocada, portanto métodos acurados de quantificação se fazem necessários. Diversas técnicas comerciais estão disponíveis para a quantificação da carga viral do HIV-1: a maioria destas se baseiam na detecção de ácidos nucléicos e outras na detecção de enzimas e antígenos. O grau de automação varia nas diferentes técnicas assim como os procedimentos de isolamento, amplificação e detecção. A correlação e a concordância entre estas técnicas têm sido estudadas e há relatos de discordância entre os valores de carga viral produzidos por diferentes métodos. O conhecimento sobre o efeito das variações entre as técnicas se faz necessário para assegurar a interpretação adequada dos resultados. A interpretação dos resultados correta é particularmente importante quando estes estão próximos a pontos de corte utilizados para definições de rebote viral e falha virológica. Objetivos: O objetivo deste estudo é comparar as técnicas de PCR (Cobas AmpliPrep TaqMan HIV-1 v2.0) e b-DNA (Siemens Versant HIV-1 RNA 3.0) para quantificação do HIV-1. Métodos: 1000 amostras recebidas no HIV/GUM Research Laboratory do Chelsea and Westminster Hospital para quantificação da carga viral do HIV-1 durante os meses de Dezembro de 2009 e Janeiro de 2010 foram testadas pelos métodos de PCR (Cobas AmpliPrep TaqMan HIV-1 v2.0) e b-DNA (Siemens Versant HIV-1 RNA 3.0). Resultados: Uma superquantificação sistemática foi observada nos resultados testados por PCR. Esta superquantificação ficou evidente nos resultados entre 50 e 250 cópias. Uma concordância elevada foi observada na análise dos pontos de corte de 500 e 1000 copias/mL. Uma correlação linear forte foi observada entre estas técnicas na análise das amostras que obtiveram resultados dentro do limite comum de detecção de ambas as técnicas, porém o nível de concordância foi insatisfatório. Conclusão: A superquantificação observada nos resultados obtidos pelo Cobas AmpliPrep TaqMan HIV- 1 v2.0 em relação ao bDNA Siemens Versant HIV-1 RNA 3.0 é provavelmente o resultado de uma sensibilidade aumentada desta técnica. Nós recomendamos cautela quando resultados de duas metodologias diferentes são comparados, especialmente quando se comparam metodologias convencionais com aquelas baseadas em PCR em tempo real. / Introduction: AIDS (Acquired Immunodeficiency Syndrome) is characterised by a severe immune dysfunction caused by the HIV (Human Immunodeficiency Virus). The HIV viral load quantification is an essential tool to monitor HIV-infected patients. The HIV quantification is a disease progression marker and it is a key indicator in treatment efficacy. Inaccurate viral RNA values may subsequently lead to inappropriate treatment decisions hence accurate quantification methods are necessary. Several different methodologies are available to quantify the HIV viral load: a number of them are based on nucleic acid detection and others in detection of enzymes and antigens. Automation is also variable among these methods in addition to differences in isolation, amplification and detection. Several studies have been carried out to evaluate their correlation and agreement and some have evidenced discordant viral load values assessed by different assays. The knowledge about these differences should be taken in to account when analysing viral load results, particularly when low-level viraemia is concerned or those close to endpoints employed for definition of virological failure. Objectives: In this study, two methods to quantify viral load are evaluated: one is based on real-time PCR (AmpliPrep TaqMan HIV-1 v2.0) and the other is based on branched-DNA technology (Siemens Versant HIV-1 RNA 3.0). Methods: 1000 plasma samples received at the HIV/GUM Research Laboratory within Chelsea and Westminster Hospital for HIV-1 viral load quantification between December 2009 and January 2010 were tested by both Cobas AmpliPrep TaqMan HIV-1 v2.0 and Siemens Versant HIV-1 RNA 3.0 methods. Results: Results obtained show that Cobas AmpliPrep TaqMan HIV-1 v2.0 PCR systematically overquantifies the viral loads results when compared to bDNA Siemens Versant HIV-1 RNA 3.0. Conclusion: The overquantification by Cobas AmpliPrep TaqMan HIV-1 v2.0 over bDNA Siemens Versant HIV-1 RNA 3.0 is likely to be a result of its increased sensitivity. We recommend caution when comparing results from different methodologies, especially when a conventional assay and a real-time PCR assay are concerned.

Host shifts -- where a pathogen jumps from one host species to another -- have been described as one of the main factors leading to emerging infectious diseases (EID). The harm that a pathogen causes to a host (virulence) varies following a host shift. Differences in susceptibilities among host species means that pathogens may be more likely to switch between certain groups of hosts. Factors that determine the variation in host susceptibility are still unknown, but one possible predictor is the host evolutionary history. Here, we examine how phylogenetically related hosts vary in susceptibility when dealing with infections of two viruses differing in pathogenicity. We infected 39 species of Drosophilidae with Drosophila A virus (DAV), a virus initially described as avirulent, and we measured host mortality (virulence) and virus replication (viral load). Then, we compared our results to previously collected data from the virulent Drosophila C virus (DCV) and we analysed the data of both viruses together. We found large variation in DAV virulence and viral load, with benign infections in some cases and high mortality in others. There was phylogenetic correlation in viral load, with species presenting similar viral load clustering together in the phylogeny. However, we did not find correlation for virulence, indicating that DAV virulence was not predictable based on viral load. Also, we did not find correlation between DAV and DCV results, indicating that variation in host susceptibility is not predictable by other pathogens infections. It is possible that hosts and parasites ecology or genetic traits may be also influencing susceptibility variation. These results suggest that although some traits are predicted by phylogeny, to determine the factors driving host susceptibility variation to different pathogens following host shifts is a very complex task / Trocas de hospedeiro -- quando um patógeno passa de uma espécie de hospedeiro para outra -- são descritas como um dos principais fatores causadores de doenças infecciosas emergentes (DIE). O dano que um patógeno causa a seu hospedeiro (virulência) varia quando trocas de hospedeiro ocorrem. Diferenças em susceptibilidade entre espécies de hospedeiros indicam que patógenos são mais propensos a realizar trocas entre determinados grupos de hospedeiros. Os fatores que determinam a variação na susceptibilidade do hospedeiro ainda são desconhecidos, porém um possível preditor é a história evolutiva do hospedeiro. Nesse estudo, nós examinamos como hospedeiros filogeneticamente relacionados variam em susceptibilidade ao lidar com duas infecções de vírus que variam em patogenicidade. Infectamos 39 espécies de Drosophilidae com o vírus A de Drosophila (DAV), inicialmente descrito como não virulento, e medimos mortalidade do hospedeiro (virulência) e replicação viral (carga). Em seguida, nós comparamos nossos resultados com informações do vírus C de Drosophila (DCV), um virulento, e analisamos os dados dos dois vírus conjuntamente. Encontramos uma grande variação nos dados de virulência e carga viral para DAV, com infecções benignas em alguns casos e alta mortalidade em outros. Encontramos correlação para carga viral, com espécies com cargas virais semelhantes aparecendo filogeneticamente próximas. Contudo, não há correlação filogenética para virulência, indicando que a virulência de DAV não pode ser predita com base na carga viral. Além disso, nós não encontramos correlação entre os resultados de DAV e DCV, indicando que a variação na susceptibilidade não pode ser predita por infecções de outros patógenos. É possível que fatores ecológicos e genéticos do hospedeiro e do parasita estejam influenciando a variação em susceptibilidade. Esses resultados sugerem que, apesar de alguns traços possam ser preditos pela filogenia, determinar os fatores causadores da variação na susceptibilidade a diferentes patógenos após trocas de hospedeiros é um trabalho extremamente complexo