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Synergy in monoclonal antibody neutralization of HIV-1 pseudoviruses and infectious molecular clones.

Miglietta R, Pastori C, Venuti A, Ochsenbauer C, Lopalco L - J Transl Med (2014)

Bottom Line: CI values indicative of additivity and low-level antagonism were seen in 5 and 3 cases, respectively.Most pairs showed comparable synergic neutralizing effects on both virus groups, with the 4E10 + PG16 pair achieving the best synergic effects.This notion has important implications for the design and development of anti-Env bNAb-inducing vaccines and polyclonal sera for passive immunization.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy. migliettariccardo@gmail.com.

ABSTRACT

Background: Early events in HIV infection are still poorly understood; virus derived from acute infections, the transmitted/founders IMCs, could provide more reliable information as they represent strains that established HIV infection in vivo, and therefore are investigated to elucidate potentially shared biological features.

Methods: This study examined synergy in neutralization by six monoclonal antibodies targeting different domains in gp120 and gp41 and assayed in pairwise combination against 11 HIV-1 clade B strains, either Env pseudoviruses (PV, n = 5) or transmitted/founder infectious molecular clones (T/F IMCs, n = 6). Three of the early-infection env tested as PV were juxtaposed with T/F viruses derived from the same three patients, respectively.

Results: All antibodies reaching IC50 were assayed pairwise (n = 50). T/F IMCs showed overall lower sensitivity to neutralization by single antibodies than PV, including within the three patient-matched pairs. Remarkably, combination index (CI) calculated using the Chow and Talalay method indicated synergy (CI < 0.9) in 42 data sets, and occurred in T/F IMC at similar proportions (15 of 17 antibody-T/F IMC combinations tested) as in pseudoviruses (27 of 33). CI values indicative of additivity and low-level antagonism were seen in 5 and 3 cases, respectively. Most pairs showed comparable synergic neutralizing effects on both virus groups, with the 4E10 + PG16 pair achieving the best synergic effects. Variability in neutralization was mostly observed on pseudovirus isolates, suggesting that factors other than virus isolation technology, such as env conformation, epitope accessibility and antibody concentration, are likely to affect polyclonal neutralization.

Conclusions: The findings from this study suggest that inhibitory activity of bNAbs can be further augmented through appropriate combination, even against viruses representing circulating strains, which are likely to exhibit a less sensitive Tier 2 neutralization phenotype. This notion has important implications for the design and development of anti-Env bNAb-inducing vaccines and polyclonal sera for passive immunization.

No MeSH data available.


Related in: MedlinePlus

Representative example of neutralization curves obtained on TZM-bl cells, using the antibodies listed in Table 1. Pseudoviruses with the three indicated envelope glycoproteins (A,B,C) were compared to T/F IMCs (D,E,F) derived from the same subjects. Values correspond to mean of three different experiments. Curves for tested antibodies that did not reached 50% of virus neutralization at the highest concentration used (66.67ug/mL) are omitted for clarity.
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Fig2: Representative example of neutralization curves obtained on TZM-bl cells, using the antibodies listed in Table 1. Pseudoviruses with the three indicated envelope glycoproteins (A,B,C) were compared to T/F IMCs (D,E,F) derived from the same subjects. Values correspond to mean of three different experiments. Curves for tested antibodies that did not reached 50% of virus neutralization at the highest concentration used (66.67ug/mL) are omitted for clarity.

Mentions: For the three patient-matched pairs (REJO, THRO and RHPA), T/F IMCs generally showed lower sensitivity to neutralization than pseudoviruses with acute/early envs from the same patients, respectively. Among the matched virus pairs, PG16 antibody only neutralized REJO and RHPA but sensitivity to neutralization of the PV and patient-matched T/F IMC was very similar, with IC50 values of comparable magnitude (within 1.5-fold to 2.2-fold range). However, some antibodies failed in 50% neutralizing the T/F IMC counterparts of the tested PV (e.g. b12 against REJO.c, and 2 F5 against RHPA.c; Figure 1), or the corresponding IC50 value for T/F IMC was by far higher (e.g. >7-fold for 4E10 and b12 against THRO.c; Figure 1). These findings are intriguing, however, investigation of the underlying mechanism was outside of the scope and purpose of this study. Representative neutralization curves obtained for pseudoviruses (panels A-B-C) and T/F IMCs (panels D-E-F) from the same subjects (REJO, RHPA and THRO) are shown in Figure 2; neutralization curves were smooth and fulfilled standardized assay acceptance criteria.Figure 2


Synergy in monoclonal antibody neutralization of HIV-1 pseudoviruses and infectious molecular clones.

Miglietta R, Pastori C, Venuti A, Ochsenbauer C, Lopalco L - J Transl Med (2014)

Representative example of neutralization curves obtained on TZM-bl cells, using the antibodies listed in Table 1. Pseudoviruses with the three indicated envelope glycoproteins (A,B,C) were compared to T/F IMCs (D,E,F) derived from the same subjects. Values correspond to mean of three different experiments. Curves for tested antibodies that did not reached 50% of virus neutralization at the highest concentration used (66.67ug/mL) are omitted for clarity.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4274758&req=5

Fig2: Representative example of neutralization curves obtained on TZM-bl cells, using the antibodies listed in Table 1. Pseudoviruses with the three indicated envelope glycoproteins (A,B,C) were compared to T/F IMCs (D,E,F) derived from the same subjects. Values correspond to mean of three different experiments. Curves for tested antibodies that did not reached 50% of virus neutralization at the highest concentration used (66.67ug/mL) are omitted for clarity.
Mentions: For the three patient-matched pairs (REJO, THRO and RHPA), T/F IMCs generally showed lower sensitivity to neutralization than pseudoviruses with acute/early envs from the same patients, respectively. Among the matched virus pairs, PG16 antibody only neutralized REJO and RHPA but sensitivity to neutralization of the PV and patient-matched T/F IMC was very similar, with IC50 values of comparable magnitude (within 1.5-fold to 2.2-fold range). However, some antibodies failed in 50% neutralizing the T/F IMC counterparts of the tested PV (e.g. b12 against REJO.c, and 2 F5 against RHPA.c; Figure 1), or the corresponding IC50 value for T/F IMC was by far higher (e.g. >7-fold for 4E10 and b12 against THRO.c; Figure 1). These findings are intriguing, however, investigation of the underlying mechanism was outside of the scope and purpose of this study. Representative neutralization curves obtained for pseudoviruses (panels A-B-C) and T/F IMCs (panels D-E-F) from the same subjects (REJO, RHPA and THRO) are shown in Figure 2; neutralization curves were smooth and fulfilled standardized assay acceptance criteria.Figure 2

Bottom Line: CI values indicative of additivity and low-level antagonism were seen in 5 and 3 cases, respectively.Most pairs showed comparable synergic neutralizing effects on both virus groups, with the 4E10 + PG16 pair achieving the best synergic effects.This notion has important implications for the design and development of anti-Env bNAb-inducing vaccines and polyclonal sera for passive immunization.

View Article: PubMed Central - PubMed

Affiliation: Division of Immunology, Transplantation and Infectious Diseases, San Raffaele Scientific Institute, Milan, Italy. migliettariccardo@gmail.com.

ABSTRACT

Background: Early events in HIV infection are still poorly understood; virus derived from acute infections, the transmitted/founders IMCs, could provide more reliable information as they represent strains that established HIV infection in vivo, and therefore are investigated to elucidate potentially shared biological features.

Methods: This study examined synergy in neutralization by six monoclonal antibodies targeting different domains in gp120 and gp41 and assayed in pairwise combination against 11 HIV-1 clade B strains, either Env pseudoviruses (PV, n = 5) or transmitted/founder infectious molecular clones (T/F IMCs, n = 6). Three of the early-infection env tested as PV were juxtaposed with T/F viruses derived from the same three patients, respectively.

Results: All antibodies reaching IC50 were assayed pairwise (n = 50). T/F IMCs showed overall lower sensitivity to neutralization by single antibodies than PV, including within the three patient-matched pairs. Remarkably, combination index (CI) calculated using the Chow and Talalay method indicated synergy (CI < 0.9) in 42 data sets, and occurred in T/F IMC at similar proportions (15 of 17 antibody-T/F IMC combinations tested) as in pseudoviruses (27 of 33). CI values indicative of additivity and low-level antagonism were seen in 5 and 3 cases, respectively. Most pairs showed comparable synergic neutralizing effects on both virus groups, with the 4E10 + PG16 pair achieving the best synergic effects. Variability in neutralization was mostly observed on pseudovirus isolates, suggesting that factors other than virus isolation technology, such as env conformation, epitope accessibility and antibody concentration, are likely to affect polyclonal neutralization.

Conclusions: The findings from this study suggest that inhibitory activity of bNAbs can be further augmented through appropriate combination, even against viruses representing circulating strains, which are likely to exhibit a less sensitive Tier 2 neutralization phenotype. This notion has important implications for the design and development of anti-Env bNAb-inducing vaccines and polyclonal sera for passive immunization.

No MeSH data available.


Related in: MedlinePlus