Human Immunodeficiency Virus type 1 in seronegative infants born to HIV-1-infected mothers

Abstract

Background: Some individuals repeatedly exposed to Human Immunodeficiency Virus do not seroconvert and are resistant to HIV infection. Here, in a pediatric cohort of HIV seronegative infants born of HIV-infected mothers, we have studied eight non-breastfed children in whom viral DNA was detected in their PBMC. Our objective was to assess whether silent infection in these children can be explained by the presence of integrated viral DNA.

Methods: The presence of viral DNA was corroborated by nested PCR with primers for gag and the nef/LTR regions of HIV-1. Integration of HIV DNA into the host genome was assessed by an Alu-LTR PCR. Amplicons were sequenced and phylogenetic analyzes were done.

Results: HIV-1 DNA was detected in the earliest available PBMC sample from all eight infants, and two of them tested positive for HIV DNA at 2 years of age. Nested PCR resulted in the amplification of gag, nef/LTR and Alu-LTR fragments, which demostrated that HIV-1 DNA was integrated in the host cell genome. Each individual has a characteristic sequence pattern and is different from the LTR sequence of HXB2 prototype virus and other Mexican isolates.

Conclusion: HIV-1 DNA was observed in PBMC from HIV exposed seronegative children in this pediatric cohort.

Figure 1

Integrated HIV DNA in PBMC of Seronegative Children. (A) Schematic representation of PCR amplification of the HIV proviral genome. Primers used for detection of LTR (1A to 4A) and GAG (1B to 4B) fragments are indicated by small thin arrows. PCR amplifications (Alu/LTR-4) of existing Alu-HIV LTR junctions were subjected to a second round of PCR with HIV-1 LTR-specific primers LTR-1-UIRH-4 (thick arrows). (B) PCR amplifications from PBMC DNA of samples children: P1 (a-c), P2 (a-d), P3 (a-c), P4 (a), P5 (a-b), P6 (a-b), P7 (a-c) and P8 (a,b). IIIBMolt cells and PBMC of HIV infected children (PINF) were used as a positive control. PBMC of noninfected children (NI) were used as a negative control.

Figure 2

Phylogenetic relationship of LTR sequences from pediatric cohort of HIV seronegative infants. A neighbor-joining phylogenetic tree was generated from LTR sequences. Numbers at branch nodes indicate bootstrap proportions greater than 70 out of 100 bootstraps replicates. Kimura two-parameter method of estimating genetic distances was used. The patient identification is at the end of each corresponding branch. The LTR sequences of Mexican isolates (7), subtype B isolates and the consensus A, B (HXB2), C and E were included .