树突状细胞表面的一种受体与Ⅰ型艾滋病毒(HIV-1)感染淋巴细胞有关

美国和荷兰的科学家报道 ,他们在树突状细胞表面发现一个ＨＩＶ 1受体—ＤＣ ＳＩＧＮ ,这一发现使人们对ＨＩＶ 1感染淋巴细胞之前的一些问题有了更新的认识。ＨＩＶ 1首先侵入人体的粘膜 ,然后由ＤＣ ＳＩＧＮ引向淋巴细胞 ,达到该病毒的靶位。荷兰科学家首先分离出了ＤＣ ＳＩＧＮ ,它是一种分子量为44ＫＤ的蛋白质 ,能够与Ｔ细胞表面的ＩＣＡＭ 3结合 ,ＤＣ ＳＩＧＮ具有树突状细胞特异性 ,能够介导树突状细胞与幼稚Ｔ细胞之间的结合。荷兰科学家与美国科学家联合证明ＤＣ ＳＩＧＮ的氨基酸序列与Ｃ型植物血凝素相同 ,后者能与ＨＩＶ 1…     

克隆中国B,C,E亚型的HIV—1代表株建立适于我国流行株的 …

目的 构建我国人免疫缺陷病毒１型（ＨＩＶ－１）Ｂ、Ｃ和Ｅ各亚型代表株ｅｎｖ基因质粒,用于对中国ＨＩＶ－１进行分型。方法 将与我国ＨＩＶ－１ Ｂ,Ｃ和Ｅ各亚型共享序列最接近的毒株用套式聚合酶链反应（ＰＣＲ）技术扩增包膜（ｅｎｖ）基因,克隆到ｐＧＥＭ－Ｔｅａｓｙ载体中,构建成用于异源双链泳动分析（ＨＭＡ）分型的中国标准亚型质粒,并进行了序列分析和分型的敏感性分析。结果 构建的中国ＨＩＶ－１ Ｂ,Ｃ和Ｅ     

腮腺炎病毒疫苗株与野毒株的部分核苷酸序列分析

目的比较腮腺炎病毒疫苗株与野毒株的核苷酸序列差异。方法腮腺炎病毒疫苗株Ｓ７９株和ＪｅｒｙｌＬｙｎｎ株在鸡胚细胞上从第５代连续传至第２５代,采用逆转录－套式聚合酶链反应（ＲＴ－ｎＰＣＲ）法,从传代前后的腮腺炎病毒疫苗株以及野毒株的基因组中扩增血凝素－神经氨酸酶基因片段（ＨＮ）、融合蛋白基因片段（Ｆ）和小分子疏水蛋白基因（ＳＨ）,并利用双脱氧核苷酸链终止法对ＰＣＲ产物进行测序。结果传代之前第５代的两种疫苗株的目的基因的核苷酸序列完全一致;传至第２５代的Ｓ７９株的目的基因的核苷酸序列比２５代的ＪｅｒｙｌＬｙｎｎ株显示了更高的突变率。比较现行疫苗株与野毒株的核苷酸序列后发现,１９９５年分离的野毒株的核苷酸序列与疫苗株有明显的差异。结论推测Ｓ７９株可能与ＪｅｒｙｌＬｙｎｎ株同源,同一地区可能有两种以上的腮腺炎病毒野毒株导致流行性腮腺炎的发生     

逆转录病毒介导的肿瘤坏死因子肝癌特异性基因治疗实验研究

为探讨肿瘤坏死因子基因对肝癌的治疗作用，分别构建ＳＶ４０早期启动子和白蛋白增强子／启动子调控小鼠肿瘤坏死因子基因的逆转录病毒载体ＭＮＳＴ和ＭＮＡＴ，以及ＳＶ４０早期启动子和人甲胎蛋白增强子／ＳＶ４０启动子调控的逆转录病毒载体ＬＴＳＮ和ＬＴＡＳＮ。构建物导入ＰＡ３１７细胞中包装成重组病毒，感染肿瘤细胞，证明白蛋白增强子／启动子和甲胎蛋白增强子均能使肿瘤坏死因子基因在肝癌细胞中高效特异表达。ＭＮＡＴ病毒和ＰＡ３１７／ＭＮＡＴ产病毒细胞ｉｎｖｉｖｏ法基因治疗有特异抗肝癌效果。提示组织特征蛋白“持家基因”转录调控序列在肿瘤组织特异性免疫基因治疗研究中有重要意义。     

MTEC 1分泌的趋化因子引起特定亚群胸腺细胞的定向迁移

分析胸腺髓质上皮样细胞系ＭＴＥＣ１分泌的化学趋化因子对胸腺细胞亚群的趋化作用。方法以抗体加补体杀伤结合免疫磁珠及ｐａｎｎｉｎｇ法，将小鼠胸腺细胞分离纯化，获得ＣＤ４＋ＣＤ８＋（ＤＰ），ＣＤ４－ＣＤ８－（ＤＮ），ＣＤ４＋ＣＤ８－（ＣＤ４ＳＰ）及ＣＤ４－ＣＤ８＋（ＣＤ８ＳＰ）四亚群细胞，用Ｂｏｙｄｅｎ小室分析ＭＴＥＣ１┐ＳＮ对四群胸腺细胞的趋化作用。结果ＭＴＥＣ１┐ＳＮ对ＤＰ及ＣＤ４ＳＰ胸腺细胞有趋化活性（ＣＩ＝６．６±１．０及６．１±１．８）；对ＣＤ８ＳＰ细胞有中度趋化活性（ＣＩ＝３．２±１．０）；对ＤＮ趋化活性微弱（ＣＩ＝１．３±０．６）。化学趋化因子ＭＣＰ┐１纯品对ＣＤ４ＳＰ胸腺细胞显示强趋化活性（ＣＩ＝５．６），对ＤＮ胸腺细胞则无可测出趋化活性。结论ＭＴＥＣ１分泌的化学趋化因子对ＤＰ，ＣＤ４ＳＰ及ＣＤ８ＳＰ胸腺细胞有显著趋化作用，对ＤＮ胸腺细胞几乎无趋化作用。提示此类化学趋化因子有趋使胸腺发育中后期阶段的细胞向胸腺髓质区迁移和定位的作用。     

携带hIL-2cDNA的逆转录病毒载体的构建及其在人肝癌细胞中的特异表达研究

将人白细胞介素２（ｈＩＬ-２）ｃＤＮＡ克隆到逆转录病毒载体ＭＮＳＭ的ＰＬ位点　，分别构建了转录受ＳＶ４０早期启动子和人甲胎蛋白增强子调控的重组逆转录病毒载体ＭＮＳＩ和ＭＮＳＩＡ。用脂质体转染法将ＭＮＳＩ和ＭＮＳＩＡ分别转导ＰＡ３１７包装细胞，测质粒转染率为（５～２０）×１０~(－３)克隆／μｇＤＮＡ·１０~６细胞，病毒感染率为（５．４～４５０）×１０~４ＣＦＵ／ｍｌ。重组病毒在４μｇ／ｍｌ ｐｏｌｙｂｒｅｎｅ存在条件下感染人肝癌细胞、肾癌细胞和黑色素瘤细胞，Ｎｅｏ~Ｒ克隆经Ｓｏｕｔｈｅｒｎｂｌｏｔ分析证明ｈＩＬ－２ｃＤＮＡ转入人肿瘤细胞并整合，　Ｒ　ＮＡ斑点杂交及ＩＬ－２活性表达分析证明，人甲胎蛋白增强子可促进异源启动子启动ｈＩＬ－２ｃＤ－ＮＡ在合成甲胎蛋白的人肝癌细胞中高效特异转录和表达。该研究对肝癌特异性免疫增强基因治疗有重要意义。     

多发性骨髓瘤和白血病细胞中白细胞介素—6激活的核因子 …

用阻滞电泳方法检测ＩＬ－６激活的核因子,以比较在多发性骨髓瘤细胞系ＳＫＯ－００７和转染ＩＬ－６受体基因的Ｔ淋巴母细胞白血病细胞系Ｍｏｌｔ－４中ＩＬ－６信号转导的差异。结果表明,在ＳＫＯ－００７细胞中,核因子可与双链探针ＡＰＲＥ,ＳＩＥ（ｍ６７）和ＮＦ－ＩＬ－６ＲＦ结合,被激活的核因子的量与ＩＬ－６受体的水平正相关;而在转染ＩＬ－６受体基因的Ｍｏｌｔ－４细胞中,核因子只与ＡＰＲＥ和ＮＦ－ＩＬ－６ＲＥ     

脂质体介导IFNγ基因治疗小鼠肝癌的研究

以大肠杆菌β－ｇａｌ基因为报告基因，优化了３种阳离子脂质本的转染条件，评估了其转染效率。用构建的含腺相关病毒反向末端重复序列的质粒表达载体，经Ｄｏｓｐｅｒ介导将小鼠ＩＦＮγ基因导入ＭＭ４５Ｔ．Ｌｉ细胞，体外有效地表达ＩＦＮγ。瘤体内注射Ｄｏｓｐｅｒ－ｐＡＩ－ｍＩＦＮγ复合物可明显报制肿瘤生长，荷瘤小鼠生存期延长。     

7株小鼠胸腺基质细胞系诱导裸鼠骨髓干细胞表达CD4及CD8分子

为研究胸腺微环境在Ｔ细胞发育中的作用，我室在体外建立了７株小鼠胸腺基质细胞系，命名为ＭＴＥＣＩ～ＭＴＥＣ７。通过初步分离得到裸鼠骨髓富含干细胞的细胞群，表面ＣＤ４及ＣＤ８分子均为阴性。将分离的骨髓干细胞与胸腺基质细胞共育３天后，经双色荧光抗体染色，ＦＡＣＳ分析发现胸腺基质细胞可诱导裸鼠骨髓干细胞表达ＣＤ４ＣＤ８分子。ＭＴＳＣ－ＳＮ及ＭＴＳＣ主要诱导的是ＣＤ４＋ＣＤ８－细胞，部分ＣＤ４＋ＣＤ８＋细胞，而ＣＤ４－ＣＤ８＋细胞极少，这种诱导特点可能和基质细胞系的类型有关。     

HIV-1准种的变化与疾病进展关系的研究

目的　研究HIV 1准种的变化对疾病进展的影响。方法　PCR方法扩增HIV 1V3～V5区片段 ,采用HMA(异源双链泳动分析 )的方法分析 4 8例HIV/AIDS准种的变化 ,并结合HIV/AIDSCD4 T淋巴细胞计数及病毒载量的结果分析HIV 1准种的变化对疾病进程的影响。结果　在不同的疾病状态下 ,体内病毒变异是不相同的 ,在体内CD4 T淋巴细胞计数较高 ,血浆病毒载量低的个体内 ,病毒毒株有很强的变异特征 ,体内具有很高的准种复杂度 ;而在CD4 细胞数很低 ,病毒载量较高的个体 ,病毒基因变异较少 ,病毒准种较为单一。结论　HIV 1准种的变化与疾病进展相关。     

3例艾滋病患者不同组织来源HIV分离株异同性的研究

目的：了解艾滋病（AIDS）患者外周血和部分组织人免疫缺陷病毒（HIV）生物学性状和基因序列的特点。方法：将3例患者的PBMC、淋巴结活检组织或脑脊液接种于PHA刺激72h的正常人PBMC进行病毒分离，将分离的毒株接种于MT2细胞,观察分离株的致细胞病毒性。同时提取前病毒DNA，对外膜基因进行序列分析。结果：同一患者不同组织来源的毒株，其生物学性状和基因序列存在差异；2例来自脑脊液的毒株，其基因序列与国际标准株SF162同源性较高。结论：在同一宿主体内的不同组织、体液内有不同的病毒种群存在；中国部分HIV感染者中存在与国际标准株同源的嗜神经株。     

Indian primary HIV-2 isolates and relationship between V3 genotype, biological phenotype and coreceptor usage

The chemokine coreceptors play a significant role in HIV entry and pathogenesis. The V3 region of HIV envelope glycoprotein is considered as a principal determinant for viral phenotype and tropism. The present study describes lack of association between the V3 genotype and viral phenotype of 18 Indian HIV-2 isolates. The viruses were isolated, confirmed by PCR and the HIV subtypes were determined by sequencing V3 region of the env gene. The coreceptor usage and syncytium inducing (SI) capacity of isolates was determined. Our study indicated that CCR5 coreceptor usage and NSI phenotype is predominant among Indian HIV-2 isolates obtained from patients in the early stage of infection. Two of the four HIV-2 isolates obtained from the late stage patients were SI and dual tropic. Phylogenetic analysis of these isolates revealed close relatedness to the isolates from western and southern India.     

Genetically and epidemiologically related "non-syncytium-inducing" isolates of HIV-1 display heterogeneous growth patterns in macrophages

The objective of this study was to identify phenotypic parameters that could distinguish among seemingly homogeneous non-syncytium-inducing (NSI) viruses and that might provide a surrogate marker for clinical progression in pediatric human immunodeficiency virus type 1 (HIV-1) infection. We undertook a pilot analysis of 15 independent HIV-1 isolates collected prospectively from two mothers and their four children who displayed a spectrum of disease stages ranging from CDC categories A1 to C3. Viruses were evaluated for their ability to replicate in primary cells (including monocyte-derived macrophages [MDM]) and cell lines, for their co-receptor preference and for genetic features of the V3 hypervariable domain of env. Virtually all isolates displayed NSI phenotypes that were restricted in their capacity to replicate in cell lines and displayed V3 loops with uniformly low net positive charges. NSI viruses from two symptomatic children and one mother were macrophage-tropic, whereas NSI isolates from two asymptomatic children were unable to replicate in MDM and were designated primary lymphotropic viruses. Only one isolate was syncytium-inducing (SI), replicated in a variety of cell lines and in MDM, used multiple co-receptors, and was dual tropic, rather than a mixture of T-cell tropic and M-tropic viruses, as assessed by genetic analysis. Phenotypic heterogeneity among NSI viruses is revealed in the ability of isolates to replicate in MDM. This characteristic is related to disease stage and provides a potentially new in vitro criterion to distinguish among NSI isolates that is unlinked to other surrogate markers.     

The HIV-2 genotype and the HIV-1 syncytium-inducing phenotype are associated with a lower virus replication in dendritic cells

During sexual transmission, HIV infects the mucosal dendritic cells and is transferred to CD4 T cells. Whether HIV variants of a particular genetic (sub)type or phenotype selectively infect dendritic cells (DC) or are preferentially transferred to T cells remains highly controversial. To avoid the cumbersome use of primary dendritic cells, in vitro dendritic cell models were generated from precursors, either hematopoietic progenitor cells (HPC) or monocytes (MO). Productive infection in the dendritic cells and transfer of the virus to T cells was assessed for a range of HIV variants. HPC-derived dendritic cells (HPC-DC) were more susceptible to HIV-1 than to HIV-2 isolates. The HIV-1 group O strains were more productive in HPC-DC than group M, but amongst the latter, no subtype-related difference was observed. Both non-syncytium-inducing (NSI) and SI HIV isolates and lab strains could productively infect HPC-DC, albeit with a different efficiency. Adding blocking antibodies confirmed that both CCR-5 and CXCR-4 co-receptors were functional. Biological HIV-1 clones of the NSI/R5 phenotype infected more readily HPC-DC than SI/X4 clones. MO-derived dendritic cells were, however, more exclusive in their preference for NSI/R5 clones. Some HIV variants, that did not grow readily in HPC-DC alone, could be rescued by adding resting or pre-activated T cells. The present data show that HIV-2 isolates and SI clones replicate less in model-DC, but no preference for a particular HIV-1 subtype was evident. Co-culture with T cells could "correct" a limited growth in dendritic cells. Clearly, both intrinsic dendritic cell susceptibility and enhancement by T cells are explained only partly by HIV genotype and phenotype. The in vitro dendritic cell models seem useful tools to further unravel interactions between HIV, DC, and T cells.     

Co-receptor usage was more predictive than NSI/SI phenotype for HIV replication in macrophages: is NSI/SI phenotyping sufficient?

A monocyte-derived macrophage (MDM) culture assay was used to define the replication kinetics of HIV isolates. Ten-day-old MDMs were infected with HIV. Supernatants were collected and assayed for HIV p24 on days 3, 7, 10, and 14 post-infection (PI). In this assay, SF162 (macrophage tropic, NSI) produced increasing amounts of HIV p24 antigen with increasing time in culture. BRU (nonmacrophage tropic, SI) infection resulted in low levels of HIV p24 antigen with no increase in production during the culture period. A panel of 12 clinical isolates was evaluated. All isolates produced detectable levels of HIV p24 antigen in MDMs. However, the NSI viruses had significantly higher log10 HIV p24 antigen values at all times PI (P < 0.01). Co-receptor usage was determined for all 12 isolates (8 NSI and 4 SI). All SI isolates used CXCR4 for entry; two used CXCR4 only, one used CXCR4, CCR5, and CCR3, and one was a mixture of two isolates using CXCR4 and CCR5. None of the NSI viruses used CXCR4 for entry. All used CCR5 as their predominant co-receptor. Of the eight NSI isolates, three used CCR5 only, two used CCR5 and CCR2b, one used CCR5 and CCR3, and one used CCR5, CCR3, and CCR2b. Log10 HIV p24 antigen production on day 14 PI for viruses that used CCR5+CCR3 (3.79 + 1.40) was greater than for viruses that used CCR5+CCR2b (3.22 + 1.55) or CCR5 (3.32 + 1.49), and all were greater than those that used CXCR4 only (1.69 + 0.28), regardless of SI phenotype (P < 0.05). Thus, in these primary isolates, macrophage tropism and replication kinetics were closely linked to CCR5 utilization, whereas SI capacity was closely linked to CXCR4 utilization. Furthermore, viruses, which could use CCR5 and CCR3 for entry, had a replication advantage in macrophages, regardless of SI phenotype.     

Enhanced replication of M-tropic HIV-1 strains in Herpesvirus saimiri immortalised T-cells which express CCR5.

A better characterisation of mononuclear cell-tropic (M-tropic) HIV-1 is central to disease control as these viruses predominate in disease transmission. M-tropic viruses do not replicate in conventional T-cell lines, and virus titres obtained in peripheral blood mononuclear cells (PBMC) are low. Human T-lymphocytes which have been immortalised by Herpesvirus saimiri strain C488 (HVS T-cells) are highly permissive to the replication of T-cell tropic strains of HIV. This study aimed to determine if HVS T-cells support replication of M-tropic HIV isolates that have not been adapted to conventional T-cell lines. A panel of PBMC low passage/primary field isolates and their molecular clones was used. Results show that infection in HVS T-cells was longer lived than in PBMC. In terms of peak virus titre and duration of productive infection, the two HVS T-cell lines studied were superior to PBMC, and one supported enhanced replication of all M-tropic isolates. This is important for generating M-tropic virus pools of sufficient titre for further biological studies such as virus neutralisation, co receptor usage and testing of antivirals. Phenotypic analysis showed that HVS T-cells are CD4+-activated memory cells expressing both CXCR-4 and CCR5 co receptors. Thus, HVS immortalisation appears to select for the T-cell subset targeted by HIV-1 in vivo.     

Presence of Intact vpu and nef genes in nonpathogenic SHIV is essential for acquisition of pathogenicity of this virus by serial passage in macaques

Use of the macaque model of human immunodeficiency virus (HIV) pathogenesis has shown that the accessory genes nef and vpu are important in the pathogenicity of simian immunodeficiency virus (SIV) and simian-human immunodeficiency virus (SHIV). We examined the ability of two nonpathogenic SHIVs, SHIV(PPC) and DeltavpuDeltanefSHIV(PPC), to gain pathogenicity by rapid serial passage in macaques. In this study, each virus was passaged by blood intravenously four times at 4-week intervals in macaques. Animals were monitored for 40 weeks for levels of CD4 T cells and quantitative measures of virus infection. DeltavpuDeltanefSHIV(PPC) maintained a limited phase of productive replication in the four animals, with no loss of CD4(+) T cells, whereas SHIV(PPC) became more pathogenic in later passages, judging by plasma viral load and viral mRNA in lymph nodes, infectious peripheral blood mononuclear cells and CD4(+) T cell loss. The nef, LTR, and env of the SHIV(PPC) viruses underwent numerous mutations, compared to DeltavpuDeltanefSHIV(PPC). This study confirms the seminal role that nef, LTR, and vpu could play in regulation of pathogenesis of HIV infection.     

High IL-7 plasma levels may induce and predict the emergence of HIV-1 virulent strains in pediatric infection.

BACKGROUND: HIV-1 infection results in severe immunodeficiency when T-cell loss cannot be compensated. IL-7 is one of the main cytokines involved in the maintenance of T-cell homeostasis. However, IL-7 can also enhance HIV-1 replication in vivo and lead to an accelerated progression of AIDS. OBJECTIVE: The aim of our study was to evaluate if the increase of IL-7 levels in response to CD4+ T cell depletion could favor the emergence of HIV-1 strains with more aggressive phenotypes in pediatric infection. STUDY DESIGN: Plasma IL-7 levels were measured in 42 HIV-1 vertically infected infants at different times of infection, and HIV-1 isolates were obtained from primary cell cultures to determine replication rate and syncytium-inducing (SI) capability on MT-2 cell line. RESULTS: IL-7 levels were significantly higher in infants harboring HIV-1 SI strains compared to those with non-syncytium-inducing (NSI) viruses (p<0.0001). Likewise, IL-7 levels were higher in infants with rapid replicating viral strains versus those with slow replicating viruses (p=0.0006). Despite the strong negative correlation between IL-7 levels and CD4+ T lymphocyte counts (r=-0.55, p=0.0001), covariance analysis demonstrated that the high levels of IL-7 were associated with more virulent phenotype features (SI and rapid replicating strains) independently of CD4+ T cell depletion. In 19 of the 42 infants, longitudinal follow-up studies showed that SI to NSI phenotype switch can occur after HAART administration, with a reduction in IL-7 levels and an increase in CD4+ T cell counts. CONCLUSIONS: IL-7 response to T-cell depletion may enhance T-cell production, but at the same time may foster HIV-1 disease progression favoring the emergence of more virulent HIV-1 strains characterized by SI capability and rapid replication rate.     

Cross-clade CD8 T-cell responses to HIV(IIIB) and Chinese B' and C/B' viruses in North American and Chinese HIV-seropositive donors

HIV variation presents an obstacle to a global AIDS vaccine. Viral diversity and host variations in MHC expression both affect vaccine responses. Whether CD8 T cells from HIV-infected donors in 1 part of the world cross-recognize isolates from other regions will provide guidance about whether country-specific vaccines are needed. We compared recognition of HIV(IIIB) and representative B' (Thai B) and recombinant C/B' virus strains endemic in China by CD8 T cells from 7 HIV-infected North American donors and 4 Chinese donors. IFN-gamma production in response to HIV(IIIB) or the Chinese viruses was comparable. Although 1.6 +/- 0.8% of American donor CD8 T cells produced IFN-gamma above the background level in response to IIIB virus, 1.5 +/- 0.8% responded to B' virus, and 1.4 +/- 0.7% responded to C/B' virus. Responses to adherent cells infected with vaccinia viruses expressing B' and C/B' virus gag and env were also comparable in magnitude with responses to IIIB virus. Cytolysis of CD4 T cells infected with B' virus was comparable with lysis of cells infected with IIIB virus, but lysis of the more divergent C/B' virus was somewhat reduced. T cells, selected for IFN-gamma production to IIIB virus, also efficiently lysed cells infected with Chinese viruses. Therefore, cross-clade CD8 T-cell responses to IIIB virus and prevalent Chinese viral strains are common.     

HIV-1 evolves into a nonsyncytium-inducing virus upon prolonged culture in vitro.

HIV-1 LAI is a syncytium-inducing (SI) virus with a broad host cell range. We previously isolated a LAI variant that improved replication in the SupT1 T cell line due to mutations within the C1 and C4 constant regions of the Env protein. We now report that this variant exhibits a severely restricted host cell range, as replication in other T cell lines and primary cells was abolished. Several Env-mediated functions were analyzed to provide a mechanistic explanation for this selective adaptation. The change in host cell tropism was not caused by a switch to a SupT1-specific coreceptor. Biosynthesis of the variant Env glycoprotein was not improved in SupT1 cells, and in fact a small defect in intracellular Env processing was observed. SupT1 infection assays did not reveal an improved Env function either, and a dramatic loss of infectivity was measured with other cell types. The Env-mutated HIV-1 reached an approximately fivefold higher level of virus production in SupT1 cells at the peak of infection. Unlike the LAI virus, the variant did not trigger the formation of syncytia. Our combined results suggest that the HIV-1 variant allows the infected host cell to survive longer, thus producing more viral progeny. The intricate virus-cell interaction results in a balance between optimal virus replication and host cell survival, causing a cytopathic SI isolate to evolve toward a nonsyncytium-inducing (NSI) phenotype in cell culture. These findings may help explain the absence of SI variants in the initial phase of HIV-1 infection, and the results dispute the notion that HIV-1 evolution should always go from the NSI to SI phenotype.