Therapeutic prediction of HIV-1 DNA decay: a multicenter longitudinal cohort study.

BACKGROUND: Factors predicting peripheral blood total HIV-1 DNA size in chronically infected patients with successfully suppressed viremia remain unclear. Prognostic power of such factors are of clinical significance for making clinical decisions. METHODS: Two sets of study populations were included: 490 China AIDS Clinical Trial (CACT) participants (Training cohort, followed up for 144 to 288 weeks) and 117 outpatients from Peking Union Medical College Hospital (PUMCH) (Validation cohort, followed up for more than 96 weeks). All patients were chronically HIV-1-infected and achieved successful HIV-1 plasma RNA suppression within week 48. Total HIV-1 DNA in blood at baseline, 12, 24, 48, 96, 144 and 288 weeks after combined antiretroviral therapy (cART) initiation were quantified. Generalized estimating equations and logistic regression methods were used to derive and validate a predictive model of total HIV-1 DNA after 96 weeks of cART. RESULTS: The total HIV-1 DNA rapidly decreased from baseline [median = 3.00 log10 copies/106 peripheral blood mononuclear cells (PBMCs)] to week 24 (median = 2.55 log10 copies/106 PBMCs), and leveled off afterwards. Of the 490 patients who had successful HIV-1 plasma RNA suppression by 96 w post-cART, 92 (18.8%) had a low total HIV-1 DNA count (< 100 copies/106 PBMCs) at week 96. In the predictive model, lower baseline total HIV-1 DNA [risk ratio (RR) = 0.08, per 1 log10 copies/106 PBMCs, P < 0.001] and higher baseline CD4+ T cell count (RR = 1.72, per 100 cells/µL, P < 0.001) were significantly associated with a low total HIV-1 DNA count at week 96. In an independent cohort of 117 patients, this model achieved a sensitivity of 75.00% and specificity of 69.52%. CONCLUSIONS: Baseline total HIV-1 DNA and CD4+ T cell count are two independent predictors of total HIV-1 DNA after treatment. The derived model based on these two baseline factors provides a useful prognostic tool in predicting HIV-1 DNA reservoir control during cART.

Residual amount of HBV DNA in serum is related to relapse in chronic hepatitis B patients after cessation of nucleos(t)ide analogs.

OBJECTIVE: To investigate the relationship between relapse and the levels of the residual amount of HBV DNA in serum at cessation in chronic hepatitis B patients meeting 2008 Asian Pacific Association for the Study of the Liver (APASL) nucleos(t)ide analogs (NAs) cessation criteria. METHODS: A total of 72 chronic hepatitis B patients who took NAs and had reached 2008 APASL cessation criteria entered the study. Patients were followed up for 6 months or longer after antiviral therapy was stopped. Serum HBV DNA level at cessation was detected by a highly sensitive polymerase chain reaction assay with detection limitation of 2 IU/mL. RESULTS: Of all the 72 patients, 42 patients (65.3%) relapsed after NA cessation. The detectable rate of the trace amount of HBV DNA at cessation was 41.7% by highly sensitive polymerase chain reaction reagents. The detectable rate of patients with consolidation treatment duration of <18 months was higher than that with consolidation duration of ≥18 months (47.5% vs. 15.4%, P=0.034), and the detectable rate of patients with HBeAg seroconversion within 6 months of treatment was lower than that of ≥6 months (25.0% vs. 61.5%, P=0.036). The residual amount of HBV DNA and detectable rate at cessation showed significant differences between relapsed and nonrelapsed patients (130.4±420.90 vs 44.6±155.16 IU/mL, P=0.004; 55.3% vs. 16.0%, P=0.001). The cutoff value predicting relapse was 2.24 IU/mL, with a sensitivity of 0.553 and specificity of 0.840. CONCLUSIONS: Residual amount of HBV DNA in serum at NA cessation is associated with HBV relapse. The cutoff value predicting relapse was 2.24 IU/mL, with a sensitivity of 0.553 and specificity of 0.840.

HIV-1 envelope subregion length variation during disease progression.

The V3 loop of the HIV-1 Env protein is the primary determinant of viral coreceptor usage, whereas the V1V2 loop region is thought to influence coreceptor binding and participate in shielding of neutralization-sensitive regions of the Env glycoprotein gp120 from antibody responses. The functional properties and antigenicity of V1V2 are influenced by changes in amino acid sequence, sequence length and patterns of N-linked glycosylation. However, how these polymorphisms relate to HIV pathogenesis is not fully understood. We examined 5185 HIV-1 gp120 nucleotide sequence fragments and clinical data from 154 individuals (152 were infected with HIV-1 Subtype B). Sequences were aligned, translated, manually edited and separated into V1V2, C2, V3, C3, V4, C4 and V5 subregions. V1-V5 and subregion lengths were calculated, and potential N-linked glycosylation sites (PNLGS) counted. Loop lengths and PNLGS were examined as a function of time since infection, CD4 count, viral load, and calendar year in cross-sectional and longitudinal analyses. V1V2 length and PNLGS increased significantly through chronic infection before declining in late-stage infection. In cross-sectional analyses, V1V2 length also increased by calendar year between 1984 and 2004 in subjects with early and mid-stage illness. Our observations suggest that there is little selection for loop length at the time of transmission; following infection, HIV-1 adapts to host immune responses through increased V1V2 length and/or addition of carbohydrate moieties at N-linked glycosylation sites. V1V2 shortening during early and late-stage infection may reflect ineffective host immunity. Transmission from donors with chronic illness may have caused the modest increase in V1V2 length observed during the course of the pandemic.

Preinfection human immunodeficiency virus (HIV)-specific cytotoxic T lymphocytes failed to prevent HIV type 1 infection from strains genetically unrelated to viruses in long-term exposed partners.

Understanding the mechanisms underlying potential altered susceptibility to human immunodeficiency virus type 1 (HIV-1) infection in highly exposed seronegative (ES) individuals and the later clinical consequences of breakthrough infection can provide insight into strategies to control HIV-1 with an effective vaccine. From our Seattle ES cohort, we identified one individual (LSC63) who seroconverted after over 2 years of repeated unprotected sexual contact with his HIV-1-infected partner (P63) and other sexual partners of unknown HIV-1 serostatus. The HIV-1 variants infecting LSC63 were genetically unrelated to those sequenced from P63. This may not be surprising, since viral load measurements in P63 were repeatedly below 50 copies/ml, making him an unlikely transmitter. However, broad HIV-1-specific cytotoxic T-lymphocyte (CTL) responses were detected in LSC63 before seroconversion. Compared to those detected after seroconversion, these responses were of lower magnitude and half of them targeted different regions of the viral proteome. Strong HLA-B27-restricted CTLs, which have been associated with disease control, were detected in LSC63 after but not before seroconversion. Furthermore, for the majority of the protein-coding regions of the HIV-1 variants in LSC63 (except gp41, nef, and the 3' half of pol), the genetic distances between the infecting viruses and the viruses to which he was exposed through P63 (termed the exposed virus) were comparable to the distances between random subtype B HIV-1 sequences and the exposed viruses. These results suggest that broad preinfection immune responses were not able to prevent the acquisition of HIV-1 infection in LSC63, even though the infecting viruses were not particularly distant from the viruses that may have elicited these responses.

Endogenous HIV-1 Vpr-mediated apoptosis and proteome alteration of human T-cell leukemia virus-1 transformed C8166 cells.

HIV-1 viral protein R (Vpr) can induce cell cycle arrest and cell death, and may be beneficial in cancer therapy to suppress malignantly proliferative cell types, such as adult T-cell leukemia (ATL) cells. In this study, we examined the feasibility of employing the HIV-vpr gene, via targeted gene transfer, as a potential new therapy to kill ATL cells. We infected C8166 cells with a recombinant adenovirus carrying both vpr and GFP genes (rAd-vpr), as well as the vector control virus (rAd-vector). G(2)/M phase cell cycle arrest was observed in the rAd-vpr infected cells. Typical characteristics of apoptosis were detected in rAd-vpr infected cells, including sub-diploid peak exhibition in DNA content assay, the Hoechst 33342 accumulation, apoptotic body formation, mitochondrial membrane potential and plasma membrane integrity loss. The proteomic assay revealed apoptosis related protein changes, exhibiting the regulation of caspase-3 activity indicator proteins (vimentin and Rho GDP-dissociation inhibitor 2), mitochondrial protein (prohibitin) and other regulatory proteins. In addition, the up-regulation of anti-inflammatory redox protein, thioredoxin, was identified in the rAd-vpr infected group. Further supporting these findings, the increase of caspase 3&7 activity in the rAd-vpr infected group was observed. In conclusion, endogenous Vpr is able to kill HTLV-1 transformed C8166 cells, and may avoid the risks of inducing severe inflammatory responses through apoptosis-inducing and anti-inflammatory activities.

[DC-SIGNR polymorphisms and its association with HIV-1 infection].

OBJECTIVE: To explore the association of the polymorphism of homologue of dendritic cell-specific intercellular adhesion molecule-3 (ICAM-3) grabbing nonintegrin (DC-SIGN related, DC-SIGNR) gene with the susceptibility to HIV-1 infection. METHODS: The distribution of the DC-SIGNR variants in the tandem repeat region and their association with HIV-1 infection in a cohort composed of 345 HIV-1 seropositive and 468 high-risk HIV-1 seronegative individuals was examined. RESULTS: There are 14 genotypes and 5 alleles in the DC-SIGNR repeat regions in the cohort. Although the most common DC-SIGNR allele among Chinese Han population and the Caucasian population is 7, it was found in a higher frequency in the Chinese than in Caucasians (67.1% vs.46.0%, P<0.01). HIV-1 seropositive individuals had a lower frequency of the genotype 7/7 than the high-risk seronegative individuals (38.55% vs. 48.29%, P=0.0057), but a higher frequency of genotype 9/5 (4.35% vs. 1.07%, P=0.0029). CONCLUSION: These results suggest that the tandem-repeat polymorphisms of the DC-SIGNR gene in the Chinese Han population exhibit unique genetic characteristics previously unrecognized in the Caucasian population. Genotype 9/5 seems to be a risk factor for HIV-1 infection in the Chinese population.

[Analysis of the tandem-repeat polymorphisms in DC-SIGNR alleles among drug users population with or without HIV/HCV infection].

OBJECTIVE: To study the distribution of DC-SIGN/DC-SIGNR alleles among drug user (DUs) populations with or without HIV/HCV infection in Shenzhen, and to evaluate the role of these alleles in the construction of genetic resistance to HIV or HCV and screen out the anti-HIV/HCV gene in Shenzhen. METHODS: All 500 DU blood samples were collected from Shenzhen Detoxification Center, including 313 from injected drug users (IDUs). All samples were screened for HIV and HCV antibody by means of ELISA. The genomic DNA were extracted and amplified by PCR. The neck domain repeat regions of DC-SIGN/DC-SIGNR were sequenced directly from the PCR products to confirm the amplification for some samples and all positive PCR products were analyzed by agarose gel electrophoresis. RESULTS: Of 500 samples, 97 were found HIV positive, all of which were IDUs and HCV positive. The total positive rate of HCV among all HIV negative DU was 57.57% (232/403), and it was 63.89% (138/216) among IDUs; in comparing to the 50.26% (94/187) of DUs with other manners there showed significant difference (chi(2) = 7.61, P = 0.0058). Among HIV + DUs, there was a higher proportion of patient with the DC-SIGNR 5/6 and 5/8 (Fisher's exact, P = 0.043 and P = 0.034) with statistical significance; there was no statistically significant difference between HCV + and HCV-DUs and no significant difference between IDUs and other DUs for the DC-SIGNR polymorphism. CONCLUSION: The results might indicate that DC-SIGN/DC-SIGNR polymorphism might not influence the susceptibility to HCV. Genotype 5/6 might probably have a relation with HIV infection, but still need further investigation for the low frequency.

Continued evolution of HIV-1 circulating in blood monocytes with antiretroviral therapy: genetic analysis of HIV-1 in monocytes and CD4+ T cells of patients with discontinued therapy.

The role of blood monocytes in HIV-1 infection is a relatively new field of interest. What happens to HIV-1 in monocytes and their relationship to CD4+ T cells before, during, and after suppressive antiretroviral therapy (ART) is largely unstudied. Here, considering that diversity is a good indicator of continued replication over time, we evaluated the effect of ART on HIV-1 in blood monocytes and CD4+ T cells by examining the diversity of HIV-1 from 4 infected patients who underwent and stopped therapy. We determined diversity and compartmentalization of HIV-1 between blood monocytes and CD4+ T cells in each patient in relationship to their ART regimens. Our data indicate that the rate of HIV-1 diversity increase in monocytes during therapy was significantly higher than in CD4+ T cells (P<0.05), suggesting that HIV-1 present in monocytes diversify more during therapy than in CD4+ T cells. Increased rates of HIV-1 compartmentalization between monocytes and CD4+ T cells while on therapy were also observed. These results suggest that ART inhibits HIV-1 replication in CD4+ T cells more than in blood monocytes and that better treatments to combat HIV-1 in monocytes/macrophages may be needed for a more complete suppression of HIV replication.

[Analysis of DC-SIGN and DC-SIGNR genetic polymorphism in Chinese Han population].

OBJECTIVE: To understand the genetic polymorphism of DC-SIGN's and DC-SIGNR's neck regions in normal Chinese Han population, and to obtain the genetic data of the two loci in Chinese Han population. METHODS: The genotypes and alleles of repeat sequences of DC-SIGN and DC-SIGNR neck region were typed by PCR, agarose gel electrophoresis and sequencing. Polymorphism information content (PIC) of DC-SIGNR was calculated. RESULTS: DC-SIGN genetic polymorphism was rare. Allele 7 was most and its frequency was 0.9808. 4-, 5-, 6- and 8- alleles were also found, although their frequencies were very low. Caucasians had only 6- and 8- allele mutants; DC-SIGNR genetic polymorphism was high, its PIC was 0.5312, 4-,5-,6-,7-,8-,9- alleles and 16 genotypes were found in normal Chinese Han population. The differences of 6/5,7/4,7/5,7/6,7/7,9/5,9/7,9/9 genotypes distribution and 5-,6-,7-,9- alleles frequency between normal Chinese Han population and Caucasian population were all extremely distinct (P<0.01). The inserted mutation seemed more in Chinese Hans than Caucasian population. CONCLUSION: DC-SIGN and DC-SIGNR genotypes and alleles distribution in Chinese Han population are significantly different from Caucasian population and with Chinese own population genetic characteristics, compared with Caucasians.

Most DC-SIGNR transcripts at mucosal HIV transmission sites are alternatively spliced isoforms.

The repeat region of DC-SIGNR (CD209L) is polymorphic on the genomic level, and, in a separate study, we observed a correlation between the DC-SIGNR genotype and HIV-1 susceptibility during sexual contact. However, previous investigations using immunohistochemistry failed to detect membrane-bound DC-SIGNR on cells in the genital and rectal mucosa. We therefore explored the presence of DC-SIGNR in these compartments with a more sensitive limiting dilution RT-PCR, which also allowed for quantification of alternatively spliced mRNA isoforms. DC-SIGN (CD209) and DC-SIGNR mRNA transcript isoforms were found in all 12 vaginal and two rectal biopsies obtained from 14 healthy individuals. For DC-SIGNR, we detected significantly more isoform than full-length transcripts (mean copy numbers/mug RNA: 602 vs 26; P=0.0009). Four mucosal samples lacked full-length DC-SIGNR transcripts entirely. Cloning and sequencing of DC-SIGNR mRNA in three additional individuals revealed a diverse repertoire of DC-SIGNR isoforms, many of which encoded for proteins predicted to be soluble and secreted. Indeed, in one vaginal sample, we detected only soluble isoforms. In conjunction with our prior observation that the DC-SIGNR genotype has an effect on HIV-1 transmission in vivo, these findings emphasize that DC-SIGNR, in addition to DC-SIGN, should be considered as a cofactor in sexual HIV-1 transmission. Soluble isoforms, in particular, may modulate the efficiency of viral transmission and dissemination.

Determination of DC-SIGN and DC-SIGNR repeat region variations.

DC-SIGN and DC-SIGNR efficiently bind HIV-1 and other viral as well as nonviral pathogens and assist either cis or trans infection. Both are type II transmembrane proteins that consist of an N-terminal cytoplasmic domain, a repeat region consisting of seven 23-amino-acid tandem repeats, and a C-terminal C-type carbohydrate recognition domain that binds mannose-enriched carbohydrate modifications of host and pathogen proteins. The normal functions of DC-SIGN and DC-SIGNR include binding to ICAM-2 and ICAM-3. Binding of DC-SIGN to ICAM-2 on endothelial cells facilitates chemokine-induced dendritic cell extravasation; binding to ICAM-3 on T lymphocytes provides the initial step for establishing cell-mediated immunity. Based on the number of tandem repeats, DC-SIGNR is highly polymorphic in the repeat region, while variations in DC-SIGN repeat region are rare. A change in the number of DC-SIGN and DC-SIGNR repeats may influence their normal functions as well as their binding capacity to viral and nonviral pathogens. This chapter describes the methods for detection of DC-SIGN and DC-SIGNR repeat region variations by polymerase chain reaction.

The contribution of monocyte infection and trafficking to viral persistence, and maintenance of the viral reservoir in HIV infection.

Cellular viral reservoirs and anatomic sanctuary sites allow continuing HIV-1 replication in patients with suppressed plasma viremia who are receiving highly active antiretroviral therapy and prevent eradication of HIV-1 by these regimens. Cells of macrophage lineage, including monocytes subsets within the blood, play a role in HIV-1 persistence. Evidence of sequence evolution in blood monocytes, in comparison to resting CD4+ T cells, demonstrates their distinct contribution to plasma viremia. There is evidence to suggest that a specific monocyte subset, of CD14loCD16hi phenotype, is more susceptible to HIV-1 infection than the majority of blood monocytes. Trafficking of monocytes through various tissues following their emigration from the bloodstream allows these cells to differentiate into tissue macrophages, or potentially to egress from the tissues as migratory dendritic cells. This review provides an evaluation of the contribution of monocytes to HIV-1 persistence and the HIV-1 reservoir, essential for the effective design of therapeutic eradication strategies.

Successful isolation of infectious and high titer human monocyte-derived HIV-1 from two subjects with discontinued therapy.

BACKGROUND: HIV-1 DNA in blood monocytes is considered a viral source of various HIV-1 infected tissue macrophages, which is also known as "Trojan horse" hypothesis. However, whether these DNA can produce virions has been an open question for years, due to the inability of isolating high titer and infectious HIV-1 directly from monocytes. RESULTS: In this study, we demonstrated successful isolation of two strains of M-HIV-1 (1690 M and 1175 M) from two out of four study subjects, together with their in vivo controls, HIV-1 isolated from CD4+ T-cells (T-HIV-1), 1690 T and 1175 T. All M- and T- HIV-1 isolates were detected CCR5-tropic. Both M- HIV-1 exhibited higher levels of replication in monocyte-derived macrophages (MDM) than the two T- HIV-1. Consistent with our previous reports on the subject 1175 with late infection, compartmentalized env C2-V3-C3 sequences were identified between 1175 M and 1175 T. In contrast, 1690 M and 1690 T, which were isolated from subject 1690 with relatively earlier infection, showed homogenous env C2-V3-C3 sequences. However, multiple reverse transcriptase (RT) inhibitor resistance-associated variations were detected in the Gag-Pol region of 1690 M, but not of 1690 T. By further measuring HIV DNA intracellular copy numbers post-MDM infection, 1690 M was found to have significantly higher DNA synthesis efficiency than 1690 T in macrophages, indicating a higher RT activity, which was confirmed by AZT inhibitory assays. CONCLUSIONS: These results suggested that the M- and T- HIV-1 are compartmentalized in the two study subjects, respectively. Therefore, we demonstrated that under in vitro conditions, HIV-1 infected human monocytes can productively release live viruses while differentiating into macrophages.

Blood monocytes harbor HIV type 1 strains with diversified phenotypes including macrophage-specific CCR5 virus.

BACKGROUND: Recent studies have shown that blood monocytes harbor human immunodeficiency virus type 1 (HIV-1) variants that are genotypically distinguishable from those in CD4(+) T cells. However, the biological function of monocyte-derived HIV-1 remains unclear. METHODS: Using pseudovirus assay, we analyzed the phenotype conferred by monocyte-derived HIV-1 envelopes from 8 patients. RESULTS: All pseudoviruses carrying monocyte-derived HIV-1 envelopes used CCR5; however, their use of additional coreceptors delineated 4 phenotypes in which viruses used (1) CCR5 only, (2) CCR5 and CXCR4, (3) CCR3 and CCR5, or (4) multiple coreceptors, including CCR1, CCR3, GPR15, CCR5, and CXCR4. More importantly, we observed 2 distinct cell tropism phenotypes for pseudoviruses carrying monocyte-derived envelopes: (1) monocyte-derived, macrophage-specific R5 (MDMS-R5) virus that, using CCR5 only, could infect monocyte-derived macrophages (MDMs) but not CD4(+) T cells and (2) dual tropic virus that infected both MDMs and primary CD4(+) T cells. We found blood monocytes harboring viruses with multiple phenotypes as early as 25 days before seroconversion and as late as 9 years after seroconversion. CONCLUSIONS: These data suggest that HIV-1 circulating in blood monocytes represents diverse HIV-1 with multiple phenotypes and that MDMS-R5 viruses may play an important role in infection with and persistence of HIV-1 within the monocyte/macrophage lineage.

Env length and N-linked glycosylation following transmission of human immunodeficiency virus Type 1 subtype B viruses.

Whether there is selection for specific viral Env variants upon HIV-1 transmission is controversial. We examined the V1V2 and V1V4 regions of Env in 10 new and 8 previously described transmission pairs infected with HIV-1 subtype B, including a total of 9 pairs in which the infecting partner had developed substantial viral diversity prior to transmission. We found that during transmission of HIV-1 subtype B, as well as for other subtypes reported in the past, viral populations in recipients undergo substantial genetic bottlenecks, as well as weak evidence for a propensity to replicate viruses with shorter variable loops and fewer potential N-linked glycosylation sites.

Case of yellow fever vaccine--associated viscerotropic disease with prolonged viremia, robust adaptive immune responses, and polymorphisms in CCR5 and RANTES genes.

BACKGROUND: The live attenuated yellow fever vaccine 17D (YF-17D) is one of the most effective vaccines. Despite its excellent safety record, some cases of viscerotropic adverse events develop, which are sometimes fatal. The mechanisms underlying such events remain a mystery. Here, we present an analysis of the immunologic and genetic factors driving disease in a 64-year-old male who developed viscerotropic symptoms. METHODS: We obtained clinical, serologic, virologic, immunologic and genetic data on this case patient. RESULTS: Viral RNA was detected in the blood 33 days after vaccination, in contrast to the expected clearance of virus by day 7 after vaccination in healthy vaccinees. Vaccination induced robust antigen-specific T and B cell responses, which suggested that persistent virus was not due to adaptive immunity of suboptimal magnitude. The genes encoding OAS1, OAS2, TLR3, and DC-SIGN, which mediate antiviral innate immunity, were wild type. However, there were heterozygous genetic polymorphisms in chemokine receptor CCR5, and its ligand RANTES, which influence the migration of effector T cells and CD14+CD16bright monocytes to tissues. Consistent with this, there was a 200-fold increase in the number of CD14+CD16bright monocytes in the blood during viremia and even several months after virus clearance. CONCLUSION: In this patient, viscerotropic disease was not due to the impaired magnitude of adaptive immunity but instead to anomalies in the innate immune system and a possible disruption of the CCR5-RANTES axis.

Fatal multiorgan failure due to yellow fever vaccine-associated viscerotropic disease.

Yellow fever vaccine-associated viscerotropic disease (YEL-AVD) is a rare complication of yellow fever (YF) vaccination. A previously healthy 22-year-old female died following YF vaccination despite aggressive measures. Serial viral load titers, cytokine levels and host genetic factors were evaluated in an attempt to understand this unusual and lethal outcome. The patient's high-titer vaccine viremia and possibly related minor genetic anomalies provide clues to exploring the etiology of YEL-AVD.

Evidence for persistent, occult infection in neonatal macaques following perinatal transmission of simian-human immunodeficiency virus SF162P3.

To model human immunodeficiency virus (HIV) perinatal transmission, we studied infection of simian-human immunodeficiency virus (SHIV) SF162P3 in 10 pregnant Macaca nemestrina females and their offspring. Four of nine infants born to and suckled by these dams had evidence of infection, a transmission rate of 44.4% (95% confidence interval, 13.7% to 78.8%). We quantified transplacentally acquired and de novo Env-specific immunoglobulin G (IgG), IgM, and neutralizing antibodies in newborns. Transmission of escape variants was confirmed. In utero infection (n = 1) resulted in high viremia, depletion of peripheral CD4+ T cells, and rapid evolution of env in blood and tissues. Peripartum or postpartum SHIV infection (n = 3) resulted in postacute viral control that was undetectable by very sensitive multiplex PCR, despite increasing antibodies. Seropositive infants with highly controlled viremia had homogeneous peripheral blood env sequences, and their tissues had <3 copies per million cells. A high incidence of seropositive virus-low or -negative SHIV infection in infant macaques has implications for HIV type 1 perinatal transmission and detection.

Impact of polymorphisms in the DC-SIGNR neck domain on the interaction with pathogens.

The lectins DC-SIGN and DC-SIGNR augment infection by human immunodeficiency virus (HIV), Ebolavirus (EBOV) and other pathogens. The neck domain of these proteins drives multimerization, which is believed to be required for efficient recognition of multivalent ligands. The neck domain of DC-SIGN consists of seven sequence repeats with rare variations. In contrast, the DC-SIGNR neck domain is polymorphic and, in addition to the wild type (wt) allele with seven repeat units, allelic forms with five and six sequence repeats are frequently found. A potential association of the DC-SIGNR genotype and risk of HIV-1 infection is currently under debate. Therefore, we investigated if DC-SIGNR alleles with five and six repeat units exhibit defects in pathogen capture. Here, we show that wt DC-SIGNR and patient derived alleles with five and six repeats bind viral glycoproteins, augment viral infection and tetramerize with comparable efficiency. Moreover, coexpression of wt DC-SIGNR and alleles with five repeats did not decrease the interaction with pathogens compared to expression of each allele alone, suggesting that potential formation of hetero-oligomers does not appreciably reduce pathogen binding, at least under conditions of high expression. Thus, our results do not provide evidence for diminished pathogen capture by DC-SIGNR alleles with five and six repeat units. Albeit, we cannot exclude that subtle, but in vivo relevant differences remained undetected, our analysis suggests that indirect mechanisms could account for the association of polymorphisms in the DC-SIGNR neck region with reduced risk of HIV-1 infection.

Viral evolution in macaques coinfected with CCR5- and CXCR4-tropic SHIVs in the presence or absence of vaccine-elicited anti-CCR5 SHIV neutralizing antibodies.

Macaques were immunized with SF162 Env-based gp140 immunogens and challenged simultaneously with the CCR5-tropic homologous SHIV(SF162P4) and the CXCR4-tropic heterologous SHIV(SF33A) viruses. Both mock-immunized and immunized animals became dually infected. Prior immunization preferentially reduced the viral replication of the homologous virus during primary infection but the relative replication of the two coinfecting viruses during chronic infection was unaffected by prior immunization, despite the fact that five of six immunized animals maintained a significantly lower overall viral replication that the control animals. Neutralizing antibodies participated in controlling the replication of SHIV(SF162P4), but not that of SHIV(SF33A). Dual infection resulted in the emergence and predominance within the circulating CCR5 virus pool, of a variant with a distinct neutralization phenotype. The signature of this variant was the presence of three amino acid changes in gp120, two of which were located in the receptor and coreceptor binding sites. Also, a significant fraction of the viruses circulating in the blood, as early as two weeks post-infection, was recombinants and prior immunization did not prevent their emergence. These findings provide new insights into the dynamic interaction of CCR5- and CXCR4-tropic HIV isolates that are potentially relevant in better understanding HIV-mediated pathogenesis.