KIR2DS4 allelic variants: Differential effects on in utero and intrapartum HIV-1 mother-to-child transmission

Distribution of KIR Genes and Their HLA Ligands in Different Viral Infectious Diseases: Frequency Study in Sicilian Population

Natural killer (NK) cells play a role in defence against viral infections by killing infected cells or by producing cytokines and interacting with adaptive immune cells. Killer immunoglobulin-like receptors (KIRs) regulate the activation of NK cells through their interaction with human leucocyte antigens (HLA). Ninety-six Sicilian patients positive to Human Immunodeficiency Virus-1 (HIV) and ninety-two Sicilian patients positive to SARS-CoV-2 were genotyped for KIRs and their HLA ligands. We also included fifty-six Sicilian patients with chronic hepatitis B (CHB) already recruited in our previous study. The aim of this study was to compare the distribution of KIR-HLA genes/groups of these three different infected populations with healthy Sicilian donors from the literature. We showed that the inhibitory KIR3DL1 gene and the KIR3DL1/HLA-B Bw4 pairing were more prevalent in individual CHB. At the same time, the frequency of HLA-C2 was increased in CHB compared to other groups. In contrast, the HLA-C1 ligand seems to have no contribution to CHB progression whereas it was significantly higher in COVID-19 and HIV-positive than healthy controls. These results suggest that specific KIR-HLA combinations can predict the outcome/susceptibility of these viral infections and allows to plan successful customized therapeutic strategies.

Use of Oral Polio Vaccine and the Global Incidence of Mother-to-Child Human Immunodeficiency Virus Transmission

Background

Mother-to-child transmission (MTCT) of human immunodeficiency virus (HIV) is an important global health issue. We hypothesized that the live attenuated poliovirus existing in oral polio vaccine (OPV) may protect uninfected neonates born to HIV-positive mothers through the stimulation of innate immune system.

Objective

To test the hypothesis that countries using OPV have a lower MTCT rate (due to postnatal protection provided by the vaccine) compared with those using only inactivated polio vaccine (IPV).

Methods

In an ecological study, the incidence of HIV/AIDS in children aged <1 year (IncHIV1), considered a surrogate index for MTCT rate, was compared between countries using OPV vs. IPV. The aggregated population data were retrieved for 204 countries from the Global Burden of Disease (GBD 2019) Collaborative Network website, “Our World in Data” website, the World Bank website, and the WHO Global Polio Eradication Initiative (GPEI). We used a negative binomial regression model with IncHIV1 as the dependent variable and the prevalence of HIV/AIDS in women aged 15–49 years (PrevHIV), antiretroviral therapy (ART) coverage, human development index (HDI), and the type of vaccine used in each country as independent variables. Multivariate imputation by chained equations was used to treat missing values. Analyses were performed for both the original dataset (with missing values) and the five imputed datasets.

Results

IncHIV1 and PrevHIV were available for all 204 countries; vaccine type, 194 countries; HDI, 182 countries; and ART coverage, 133 countries. One-hundred and twenty-nine countries in the original dataset had complete data for all the above-mentioned variables; the imputed datasets had complete data for all 204 countries. The results obtained from the analysis of the original dataset had no overall difference with the pooled results obtained from the analysis of the five imputed datasets. Countries with higher HDI mainly use IPV; those with lower HDI commonly use OPV. PrevHIV, HDI, and the type of vaccine were independent predictors of IncHIV1. Use of OPV compared to IPV, was independently associated with an average decrease of 17% in IncHIV1 at the median HDI of 0.75. The protection provided by OPV increased in countries with lower HDI.

Conclusions

Use of OPV compared with IPV, was independently associated with lower MTCT rate.

Association of SNPs in HLA-C and ZNRD1 Genes With HIV-1 Mother-to-Child Transmission in Zambia Population

BACKGROUND

Human leukocyte antigen C (HLA-C) and Zinc ribbon domain containing 1 (ZNRD1) are considered HIV-1 restriction factors and are expressed in the placenta. Variations in HLA-C and ZNRD1 genes are known to influence HIV-1 infection, including viral replication and progression to AIDS. Little is known about the role of variants in these genes in HIV-1 mother-to-child transmission.

METHODS

We evaluated the distribution of HLA-C (rs10484554, rs9264942) and ZNRD1 (rs8321, rs3869068) variants in a Zambian population composed of 333 children born to HIV-1+ mothers (248 HIV-1 noninfected/85 HIV-1 infected) and 97 HIV-1+ mothers.

RESULTS

Genotypic distribution of HLA-C and ZNRD1 were in Hardy-Weinberg equilibrium, except for HLA-C rs10484554 in both groups. In mothers, no significant differences were observed in their allele and genotypic distributions for both genes. The T and TT variants (rs10484554-HLA-C) were significantly more frequent among HIV-1+ children, specifically those who acquired the infection in utero (IU) and intrapartum (IP). For ZNRD1, the T allele (rs3869068) was more frequent in HIV-1- children, showing significant differences in relation to those infected via IP and postpartum (PP). The CT and TT genotypes were significantly more frequent in HIV-1- children.

CONCLUSIONS

Variations in HLA-C (T and TT-rs10484554) and ZNRD1 (T and CT/TT-rs3869068) can increase and decrease the susceptibility to HIV-1 infection via mother-to-child transmission, respectively. Further studies are encouraged focusing on a greater number of variants and sample size, with functional validation and in other populations.

Natural killer cell receptor variants and chronic hepatitis B virus infection in the Vietnamese population

OBJECTIVES

Genes of host immunity play an important role in disease pathogenesis and are determinants of clinical courses of infections, including hepatitis B virus (HBV). Killer-cell immunoglobulin-like receptor (KIR), expressed on the surface of natural killer cells (NK), regulate NK cell cytotoxicity by interacting with human leukocyte antigen (HLA) class I molecules and are candidates for influencing the course of HBV. This study evaluated whether variations in KIR gene content and HLA-C ligands are associated with HBV and with the development of liver cirrhosis and hepatocellular carcinoma.

METHODS

A Vietnamese study cohort (HBV n = 511; controls n = 140) was genotyped using multiplex sequence-specific polymerase chain reaction (PCR-SSP) followed by melting curve analysis.

RESULTS

The presence of the functional allelic group of KIR2DS4 was associated with an increased risk of chronic HBV (OR = 1.86, p^corr = 0.02), while KIR2DL2+HLA-C1 (OR = 0.62, p^corr = 0.04) and KIR2DL3+HLA-C1 (OR = 0.48, p^corr = 0.04) were associated with a decreased risk. The pair KIR2DL3+HLA-C1 was associated with liver cirrhosis (OR = 0.40, p^corr = 0.01). The presence of five or more activating KIR variants was associated with hepatocellular carcinoma (OR = 0.53, p^corr = 0.04).

CONCLUSIONS

KIR gene content variation and combinations KIR-HLA influence the outcome of HBV infection.

A child with perinatal HIV infection and long-term sustained virological control following antiretroviral treatment cessation

Understanding HIV remission in rare individuals who initiated antiretroviral therapy (ART) soon after infection and then discontinued, may inform HIV cure interventions. Here we describe features of virus and host of a perinatally HIV-1 infected child with long-term sustained virological control. The child received early limited ART in the Children with HIV Early antiRetroviral therapy (CHER) trial. At age 9.5 years, diagnostic tests for HIV are negative and the child has characteristics similar to uninfected children that include a high CD4:CD8 ratio, low T cell activation and low CCR5 expression. Virus persistence (HIV-1 DNA and plasma RNA) is confirmed with sensitive methods, but replication-competent virus is not detected. The child has weak HIV-specific antibody and T cell responses. Furthermore, we determine his HLA and KIR genotypes. This case aids in understanding post-treatment control and may help design of future intervention strategies.

Some perinatally HIV infected children who have received early antiretroviral therapy (ART) show long-term sustained virological control after ART cessation. Here the authors describe a case who, at age 9.5 years, shows normal CD4:CD8 T cell ratios and has no detectable levels of replication-competent virus.

Association of maternal KIR gene content polymorphisms with reduction in perinatal transmission of HIV-1

The role of killer cell immunoglobulin-like receptors (KIRs) in the transmission of HIV-1 has not been extensively studied. Here, we investigated the association of KIR gene content polymorphisms with perinatal HIV-1 transmission. The KIR gene family comprising 16 genes was genotyped in 313 HIV-1 positive Kenyan mothers paired with their infants. Gene content polymorphisms were presented as presence of individual KIR genes, haplotypes, genotypes and KIR gene concordance. The genetic data were analyzed for associations with perinatal transmission of HIV. There was no association of infant KIR genes with perinatal HIV-1 transmission. After adjustment for gravidity, viral load, and CD4 cell count, there was evidence of an association between reduction in perinatal HIV-1 transmission and the maternal individual KIR genes KIR2DL2 (adjusted OR = 0.50; 95% CI: 0.24–1.02, P = 0.06), KIR2DL5 (adjusted OR = 0.47; 95% CI: 0.23–0.95, P = 0.04) and KIR2DS5 (adjusted OR = 0.39; 95% CI: 0.18–0.80, P = 0.01). Furthermore, these maternal KIR genes were only significantly associated with reduction in perinatal HIV transmission in women with CD4 cell count ≥ 350 cells/ μl and viral load <10000 copies/ml. Concordance analysis showed that when both mother and child had KIR2DS2, there was less likelihood of perinatal HIV-1 transmission (adjusted OR = 0.44; 95% CI: 0.20–0.96, P = 0.039). In conclusion, the maternal KIR genes KIR2DL2, KIR2DL5, KIR2DS5, and KIR2DS2 were associated with reduction of HIV-1 transmission from mother to child. Furthermore, maternal immune status is an important factor in the association of KIR with perinatal HIV transmission.

The Role of Immune Responses in HIV Mother-to-Child Transmission

HIV mother-to-child transmission (MTCT) represents a success story in the HIV/AIDS field given the significant reduction in number of transmission events with the scale-up of antiretroviral treatment and other prevention methods. Nevertheless, MTCT still occurs and better understanding of the basic biology and immunology of transmission will aid in future prevention and treatment efforts. MTCT is a unique setting given that the transmission pair is known and the infant receives passively transferred HIV-specific antibodies from the mother while in utero. Thus, infant exposure to HIV occurs in the face of HIV-specific antibodies, especially during delivery and breastfeeding. This review highlights the immune correlates of protection in HIV MTCT including humoral (neutralizing antibodies, antibody-dependent cellular cytotoxicity, and binding epitopes), cellular, and innate immune factors. We further discuss the future implications of this research as it pertains to opportunities for passive and active vaccination with the ultimate goal of eliminating HIV MTCT.

KIR Gene Content Diversity in a Zimbabwean Population: Does KIR2DL2 Have a Role in Protection Against Human Immunodeficiency Virus Infection?

Killer cell immunoglobulin-like receptors (KIRs) mediate natural killer cell function through interaction with their cognate human leukocyte antigen ligands. Thus, KIR gene variants have been implicated in resistance or susceptibility to viral infections. However, research on the role of these variants remains contradictory and inconclusive. In the present study, we investigated KIR gene content diversity and its association with human immunodeficiency virus (HIV) infection in an adult Black Zimbabwean population. Presence or absence of 15 KIR genes was determined in 189 HIV-infected adults and 97 HIV-uninfected blood donors using sequence specific primer polymerase chain reaction. Frequencies of KIR genes, genotypes, and haplotypes were compared between the cases and controls to identify putative associations between KIR gene variants and HIV status. We report in this study the frequencies of 15 KIR genes and 43 KIR genotypes (40 known and 3 novel) among Zimbabweans. Importantly, the frequency of the inhibitory KIR2DL2 gene was significantly higher in the uninfected group (62%) compared to the HIV-infected group (47%) (OR = 0.55, 95% CI: 0.33-0.90, p = 0.019). KIR2DL2/2DL2 homozygosity was also significantly higher in the uninfected group (35%) compared to HIV-infected group (53%) (OR = 0.33, 95% CI: 0.16-0.72, p = 0.005) under a recessive model. We conclude that the KIR2DL2 gene may be involved in protection against HIV infection. It may be possible that inhibitory KIR genes may have an important role to play in HIV acquisition among populations of African origin in whom the activating KIR genes are less frequent compared to among Caucasians.

Killer-cell immunoglobulin-like receptor (KIR) and human leukocyte antigen (HLA) class I genetic diversity in four South African populations

Killer-cell Immunoglobulin-like Receptor (KIR) and Human Leukocyte Antigen (HLA) genotypes vary considerably between individuals and populations due to KIR/HLA allelic variation and variable haplotype configurations of KIR. HLA mediate natural killer cell activity by serving as KIR ligands. KIR/HLA polymorphisms associate with both disease susceptibility and severity. We determined the frequencies of KIR, KIR genotypes and KIR-HLA combinations in 364 healthy individuals from four South African populations. Study participants included black African (n=167), Caucasian (n=97), Mixed ancestry (n=50) and Indian (n=50) individuals. We identified 48 KIR genotypes that included two genotypes not previously reported. Based on KIR gene content, Indian individuals represented the most distinct group, showing the highest frequencies of KIR2DL2, KIR2DL5, KIR2DS1, KIR2DS2, KIR2DS3 and KIR3DS1, the lowest frequencies of KIR2DL3, KIR2DS4 and KIR3DL1; and a KIR2DL4-negative individual. KIR2DS1 and KIR3DS1 were infrequent in black African populations. HLA-C2 was more common in black African individuals, while HLA-C1 predominated in the other populations. Indian individuals were more likely to possess KIR2DL2 paired with HLA-C1, while Caucasian individuals exhibited the highest frequencies of KIR2DL3 paired with HLA-C1. This report provides comprehensive reference data for further study of the roles of KIR/HLA in non-communicable and infectious diseases in South African populations.

Typing of killer-cell immunoglobulin-like receptors and their cognate human leukocyte antigen class I ligands predicts survival of Chinese Han patients with metastatic non-small-cell lung cancer

Non-small-cell lung cancer (NSCLC) may establish an immunosuppressive tumor microenvironment that is conducive to tumor growth. Natural killer (NK) cells play a pivotal role in immunological surveillance. Activation of NK cells partially depends on the interactions between killer-cell immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) class I ligands. We herein investigated the association of KIRs and HLA ligands with survival in metastatic NSCLC (mNSCLC) patients treated with chemotherapy in a Chinese Han population. Polymerase chain reaction with sequence-specific primers was used to type 15 KIRs at the DNA and mRNA level and 6 HLA ligands in 70 mNSCLC patients. Survival curves were estimated using the Kaplan-Meier method and compared with the log-rank test. Cox proportional hazard regression model was applied for multivariate survival analysis, with the stepwise selection, to determine independent predictors of survival. It was observed that patients with KIR2DS4del gene expression at the mRNA level or HLA-Bw4T80 exhibited poor overall survival (OS). The multivariate analysis revealed that HLA-Bw4T80 and KIR2DS4del expression were independent predictors of OS. This observation indicated that the KIR/HLA ligand is a promising predictor of survival in mNSCLC and may also provide a strategy for treatment stratification and patient management.

Activating KIR2DS4 Is Expressed by Uterine NK Cells and Contributes to Successful Pregnancy

Tissue-specific NK cells are abundant in the pregnant uterus and interact with invading placental trophoblast cells that transform the maternal arteries to increase the fetoplacental blood supply. Genetic case-control studies have implicated killer cell Ig-like receptor (KIR) genes and their HLA ligands in pregnancy disorders characterized by failure of trophoblast arterial transformation. Activating KIR2DS1 or KIR2DS5 (when located in the centromeric region as in Africans) lower the risk of disorders when there is a fetal HLA-C allele carrying a C2 epitope. In this study, we investigated another activating KIR, KIR2DS4, and provide genetic evidence for a similar effect when carried with KIR2DS1 KIR2DS4 is expressed by ∼45% of uterine NK (uNK) cells. Similarly to KIR2DS1, triggering of KIR2DS4 on uNK cells led to secretion of GM-CSF and other chemokines, known to promote placental trophoblast invasion. Additionally, XCL1 and CCL1, identified in a screen of 120 different cytokines, were consistently secreted upon activation of KIR2DS4 on uNK cells. Inhibitory KIR2DL5A, carried in linkage disequilibrium with KIR2DS1, is expressed by peripheral blood NK cells but not by uNK cells, highlighting the unique phenotype of uNK cells compared with peripheral blood NK cells. That KIR2DS4, KIR2DS1, and some alleles of KIR2DS5 contribute to successful pregnancy suggests that activation of uNK cells by KIR binding to HLA-C is a generic mechanism promoting trophoblast invasion into the decidua.

Killer Cell Immunoglobulin-Like Receptor Alleles Alter HIV Disease in Children

BACKGROUND

HLA class I molecules are ligands for killer cell immunoglobin like receptors (KIR) that control the antiviral response of natural killer (NK) cells. However, the effects of KIR and HLA (KIR/HLA) alleles on HIV disease of children have not been studied.

METHODS

993 antiretroviral naïve children with symptomatic HIV infection from PACTG protocols P152 and P300 were genotyped for KIR and HLA alleles using the Luminex platform. Linear regression was used to test the association between genotypes and baseline pre-ART HIV RNA, CD4+ lymphocyte count, and cognitive score, adjusting for age, race/ethnicity and study. The interaction between genetic markers and age was investigated. To account for multiple testing the false discovery rate (FDR) was controlled at 0.05.

RESULTS

Children with the KIR2DS4*ALL FULL LENGTH (KIR2DS4*AFL) allele had higher CD4+ lymphocyte counts. Among children ≤2 years of age, the KIR2DS4*AFL was associated with lower plasma HIV RNA and higher cognitive index scores. KIR Cent2DS3/5_1 had lower CD4+ lymphocyte counts in children ≤2 years of age, while the presence of Tel1, Tel2DS4_2, Tel2DS4_4, Tel8, Tel2DS4_6 had higher CD4+ lymphocyte counts in all children. Presence of Cent2, Cent4 and Cent8 was associated with increased HIV RNA load in children ≤2 years. Presence of KIR3DL1+Bw4 was associated with higher CD4+ lymphocyte counts in all children. Among children >2 years old, KIR3DS1+Bw4-80I was associated with higher plasma HIV RNA, and Bw6/Bw6 was associated with lower plasma HIV RNA compared to children with KIR3DS1+Bw4-80I.

CONCLUSIONS

Presented data show for the first time that specific KIR alleles independently or combined with HLA ligands are associated with HIV RNA and CD4+ lymphocyte counts in infected, antiretroviral naive children; and many of these effect estimates appear to be age dependent. These data support a role for specific KIR alleles in HIV pathogenesis in children.

The effects of killer cell immunoglobulin-like receptor (KIR) genes on susceptibility to HIV-1 infection in the Polish population

Killer cell immunoglobulin-like receptors (KIR) are the most polymorphic receptors of natural killer (NK) cells. Their activity diversifies the functions of NK cells in the antiviral immune response, so the presence of certain KIR may affect transmission of HIV-1. The aim of the study was to evaluate the influence of KIR genes on the susceptibility to HIV-1 infection in the Polish population depending on the route of exposure. We determined the frequencies of activating (2DS1, 2DS2, 2DS3, 2DS4f, 2DS4del, 2DS5, 3DS1) and inhibitory (2DL1, 2DL2, 2DL3, 2DL5, 3DL1) KIRs in HIV-1-positive patients (n = 459), individuals exposed to HIV-1 but uninfected (EU, n = 118) and in uninfected, healthy blood donors (BD, n = 98). Analysis was performed using stepwise logistic regression. Apart from KIRs, CCR5-∆32, and CCR2-64I, alleles were also analyzed, as we knew or suspected that these features could affect susceptibility to HIV infection. The regression confirmed the protective effect of CCR5-∆32 (OR = 0.25, p = 0.006) and CCR2-64I (OR = 0.59, p = 0.032) against HIV infection. Among KIR genes, 2DL3 was found to be a protective factor (OR = 0.30, p = 0.015). A similar effect was seen for 3DS1 but only in intravenous drug users (IDUs) (OR = 0.30, p = 0.019), not in sexually exposed people. 2DL5 was found to be a factor facilitating HIV infection (OR = 2.13, p = 0.013). A similar effect was observed for 2DL2 but only in females (OR = 2.15, p = 0.040), and 2DS1 in IDUs (OR = 3.03, p = 0.022). Our results suggest a beneficial role of KIR3DS1 and 2DL3 supporting resistance to HIV infection and a harmful effect of 2DS1, 2DL5, and 2DL2 genes promoting HIV acquisition.

KIR diversity in three ethnic minority populations in China

BACKGROUND

Killer cell immunoglobulin-like receptors (KIRs) show extensive variation in genetic content and allelic polymorphi sms among different populations.

MATERIALS AND METHODS

We analyzed the distribution of KIR genes in the Tibetan ethnic minority of Lhasa city, the Uyghur and Kazakh ethnic minorities of Urumqi city populations in China. Genotyping of 16 KIR genes was tested in 479 randomly selected individuals using the multiple PCR-SSP method.

RESULTS

A total of 42 KIR genotypes were detected, of which, 29 were predicted to be AB genotypes, 12 were BB genotypes and one was AA genotypes. 27 KIR genotypes were identified in Kazakhs, 30 KIR genotypes were identified in Uyghurs and 20 KIR genotypes were identified in Tibetans. The predominant genotype 1(AA genotypes) occurred most frequently in Tibetans (52.7%, 118/224), Kazakhs (43.2%, 54/125) and Uyghurs (34.9%, 45/130). Not only the four framework genes were present in all individuals, but the pseudogene 2DP1 could also be detected in all Uyghur individuals. Tibetans were different from Kazakh and Uyghur groups in KIR genetic content and KIR allelic variation. Intriguingly, Tibetans (29.5%, 66/224) had lower frequencies of 2DS4-v when compared with Uyghurs (60.8%, 79/130) and Kazakh s (59.2%, 74/125). Uyghurs (25.4%, 33/130) displayed higher frequencies of Bx genotypes with C4Tx (absence of KIR3DS1-2DL5-2DS5-2DS1) than both Kazakhs (11.2%, 14/125) and Tibetans (3.6%, 8/224).

CONCLUSIONS

The study showed that profile of KIR genotypes in three ethnic minority populations in China displayed ethnic diversity. It could be valuable for enriching the ethnical information resources for KIR gene, as well as facilitating further research on KIR-related diseases.

The HLA-C*04: 01/KIR2DS4 gene combination and human leukocyte antigen alleles with high population frequency drive rate of HIV disease progression

OBJECTIVE

The objective of this study is to identify human leukocyte antigen (HLA) class I and killer-cell immunoglobulin-like receptor (KIR) genotypes associated with different risks for HIV acquisition and HIV disease progression.

DESIGN

A cross-sectional study of a cohort of 468 high-risk individuals (246 HIV-positive and 222 HIV-negative) from outpatient clinics in Lima (Perú).

METHODS

The cohort was high-resolution HLA and KIR-typed and analysed for potential differences in single-allele frequencies and allele combinations between HIV-positive and HIV-negative individuals and for associations with HIV viral load and CD4 cell counts in infected individuals.

RESULTS

HLA class I alleles associated with a lack of viral control had a significantly higher population frequency than relatively protective alleles (P = 0.0093), in line with a rare allele advantage. HLA-A02 : 01 and HLA-C04 : 01 were both associated with high viral loads (P = 0.0313 and 0.0001, respectively) and low CD4 cell counts (P = 0.0008 and 0.0087, respectively). Importantly, the association between HLA-C04 : 01 and poor viral control was not due to its linkage disequilibrium with other HLA alleles. Rather, the coexpression of its putative KIR ligand KIR2DS4f was critically linked to elevated viral loads.

CONCLUSION

These results highlight the impact of population allele frequency on viral control and identify a novel association between HLA-C04 : 01 in combination with KIR2DS4f and uncontrolled HIV infection. Our data further support the importance of the interplay of markers of the adaptive and innate immune system in viral control.

Maternal human leukocyte antigen-G (HLA-G) genetic variants associate with in utero mother-to-child transmission of HIV-1 in Black South Africans

A 14-bp insertion/deletion (indel) within the 3' untranslated region (3'UTR) that affects HLA-G expression has been associated with HIV-1 mother-to-child transmission (MTCT). However, other 3'UTR single nucleotide polymorphisms (SNPs) that influence HLA-G mRNA stability have been described but not analysed in the context of MTCT, and little is known about the role of HLA-G alleles. We examined HLA-G alleles and 3'UTR SNPs, including the 14-bp indel, in 216 mother-infant pairs from Johannesburg, South Africa. Mother-infant pairs were classified as HIV-1 non-transmitting (NT, n=144) or HIV-1 transmitting (TR, n=72) with either intrapartum (IP, n=29) or in utero (IU, n=19) infected infants. We found HLA-G allele, G(∗)01:01:02 (in strong linkage disequilibrium with the 14-bp insertion) and +3187G SNP were significantly over-represented in IU-TR mothers compared to NT mothers (P=0.036, OR=2.26; P=0.011, OR=2.96, respectively). These findings suggest that maternal HLA-G alleles and/or SNPs that might alter expression of HLA-G potentially influence IU HIV-1 MTCT.