Table_2_High seroprevalence of Leishmania infantum is linked to immune activation in people with HIV: a two-stage cross-sectional study in Bahia, Brazil.XLSX

Visceral leishmaniasis is an opportunistic disease in HIV-1 infected individuals, unrecognized as a determining factor for AIDS diagnosis. The growing geographical overlap of HIV-1 and Leishmania infections is an emerging challenge worldwide, as co-infection increases morbidity and mortality for both infections. Here, we determined the prevalence of people living with HIV (PWH) with a previous or ongoing infection by Leishmania infantum and investigated the virological and immunological factors associated with co-infection. We adopted a two-stage cross-sectional cohort (CSC) design (CSC-I, n = 5,346 and CSC-II, n = 317) of treatment-naïve HIV-1-infected individuals in Bahia, Brazil. In CSC-I, samples collected between 1998 and 2013 were used for serological screening for leishmaniasis by an in-house Enzyme-Linked Immunosorbent Assay (ELISA) with SLA (Soluble Leishmania infantum Antigen), resulting in a prevalence of previous or ongoing infection of 16.27%. Next, 317 PWH were prospectively recruited from July 2014 to December 2015 with the collection of sociodemographic and clinical data. Serological validation by two different immunoassays confirmed a prevalence of 15.46 and 8.20% by anti-SLA, and anti-HSP70 serology, respectively, whereas 4.73% were double-positive (DP). Stratification of these 317 individuals in DP and double-negative (DN) revealed a significant reduction of CD4+ counts and CD4+/CD8+ ratios and a tendency of increased viral load in the DP group, as compared to DN. No statistical differences in HIV-1 subtype distribution were observed between the two groups. However, we found a significant increase of CXCL10 (p = 0.0076) and a tendency of increased CXCL9 (p = 0.061) in individuals with DP serology, demonstrating intensified immune activation in this group. These findings were corroborated at the transcriptome level in independent Leishmania- and HIV-1-infected cohorts (Swiss HIV Cohort and Piaui Northeast Brazil Cohort), indicating that CXCL10 transcripts are shared by the IFN-dominated immune activation gene signatures of both pathogens and positively correlated to viral load in untreated PWH. This study demonstrated a high prevalence of PWH with L. infantum seropositivity in Bahia, Brazil, linked to IFN-mediated immune activation and a significant decrease in CD4+ levels. Our results highlight the urgent need to increase awareness and define public health strategies for the management and prevention of HIV-1 and L. infantum co-infection.

内脏利什曼病（Visceral leishmaniasis）是HIV-1感染者的机会性感染疾病，此前未被视为艾滋病诊断的决定性因素。HIV-1与利什曼原虫感染的地理重叠范围日益扩大，已成为全球新兴挑战：共感染会同时提升两种感染的发病率与死亡率。本研究明确了婴儿利什曼原虫（Leishmania infantum）既往或现症感染的艾滋病病毒感染者（People Living with HIV, PWH）的患病率，并探究了与共感染相关的病毒学及免疫学因素。

本研究采用两阶段横断面队列（Cross-sectional Cohort, CSC）设计，对象为巴西巴伊亚州的初治HIV-1感染者，其中CSC-I队列样本量n=5346，CSC-II队列样本量n=317。在CSC-I队列中，我们使用1998年至2013年采集的样本，通过以可溶性婴儿利什曼原虫抗原（Soluble Leishmania infantum Antigen, SLA）包被的室内酶联免疫吸附试验（Enzyme-Linked Immunosorbent Assay, ELISA）进行利什曼病血清学筛查，结果显示既往或现症感染的患病率为16.27%。

随后，我们于2014年7月至2015年12月前瞻性招募了317名PWH，采集其社会人口学与临床资料。通过两种不同免疫检测方法进行血清学验证，结果显示抗SLA血清学阳性率为15.46%，抗热休克蛋白70（Heat Shock Protein 70, HSP70）血清学阳性率为8.20%，其中4.73%为双阳性（Double-positive, DP）。

将这317名受试者按DP与双阴性（Double-negative, DN）进行分层后发现，与DN组相比，DP组的CD4+细胞计数与CD4+/CD8+比值显著降低，且病毒载量呈升高趋势；两组间HIV-1亚型分布无统计学差异。不过，DP血清学阳性者的CXCL10水平显著升高（p=0.0076），CXCL9水平呈升高趋势（p=0.061），表明该组免疫激活程度更强。

上述发现于独立的利什曼原虫及HIV-1感染队列（瑞士HIV队列及巴西东北部皮奥伊队列）的转录组水平得到证实，结果显示CXCL10转录本同时存在于两种病原体的干扰素主导的免疫激活基因特征中，且与未接受治疗的PWH的病毒载量呈正相关。

本研究证实，巴西巴伊亚州的PWH中婴儿利什曼原虫血清阳性率较高，该现象与干扰素介导的免疫激活及CD4+水平显著降低相关。研究结果凸显了提升公众认知、制定公共卫生策略以管理和预防HIV-1与婴儿利什曼原虫共感染的紧迫性。