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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

Scatter plot showing Combination Index (CI) values for the indicated two-NAb combinations against P, Pseudoviruses; T/F, Transmitted/Founder IMCs. Bars represent mean of all CI in each category (PV; T/F IMC). Each point represents the CI obtained for one of the 12 different dilutions of the two antibodies in the respective antibody combination (See Material and Methods for details). Circles and triangles represent PV and T/F IMC, respectively; each color corresponds to each single virus: Purple, SF162, Red, AC10, Blue, REJO, Green, RHPA, Pink, THRO, Brown, CH040; Dark Yellow, CH058 and Orange, CH077.
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Fig4: Scatter plot showing Combination Index (CI) values for the indicated two-NAb combinations against P, Pseudoviruses; T/F, Transmitted/Founder IMCs. Bars represent mean of all CI in each category (PV; T/F IMC). Each point represents the CI obtained for one of the 12 different dilutions of the two antibodies in the respective antibody combination (See Material and Methods for details). Circles and triangles represent PV and T/F IMC, respectively; each color corresponds to each single virus: Purple, SF162, Red, AC10, Blue, REJO, Green, RHPA, Pink, THRO, Brown, CH040; Dark Yellow, CH058 and Orange, CH077.

Mentions: The 12 individual CI values generated for each mAb combination against each tested virus strain are illustrated in Figures 4 and 5, and Table 2 summarizes mean CI values and standard deviations for all antibody combinations (n = 50), observed against pseudovirus and T/F IMC strains. CI values indicative of synergy (CI < 0.9) were observed in 42 data sets. Of those, 11 synergistic data sets (n = 8 in PV group, n = 3 in T/F IMC group; data obtained from nine different antibody combinations) with mean CI <0.9 had standard deviations that reached into the range of additivity; in Table 2 they are indicated with hatched light grey shading to distinguish them from the 5 data set for which CI values indicating additivity were obtained (medium grey shading). CI values indicative of low-level antagonism were seen in 3 cases (dark grey shading).Figure 4


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)

Scatter plot showing Combination Index (CI) values for the indicated two-NAb combinations against P, Pseudoviruses; T/F, Transmitted/Founder IMCs. Bars represent mean of all CI in each category (PV; T/F IMC). Each point represents the CI obtained for one of the 12 different dilutions of the two antibodies in the respective antibody combination (See Material and Methods for details). Circles and triangles represent PV and T/F IMC, respectively; each color corresponds to each single virus: Purple, SF162, Red, AC10, Blue, REJO, Green, RHPA, Pink, THRO, Brown, CH040; Dark Yellow, CH058 and Orange, CH077.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Fig4: Scatter plot showing Combination Index (CI) values for the indicated two-NAb combinations against P, Pseudoviruses; T/F, Transmitted/Founder IMCs. Bars represent mean of all CI in each category (PV; T/F IMC). Each point represents the CI obtained for one of the 12 different dilutions of the two antibodies in the respective antibody combination (See Material and Methods for details). Circles and triangles represent PV and T/F IMC, respectively; each color corresponds to each single virus: Purple, SF162, Red, AC10, Blue, REJO, Green, RHPA, Pink, THRO, Brown, CH040; Dark Yellow, CH058 and Orange, CH077.
Mentions: The 12 individual CI values generated for each mAb combination against each tested virus strain are illustrated in Figures 4 and 5, and Table 2 summarizes mean CI values and standard deviations for all antibody combinations (n = 50), observed against pseudovirus and T/F IMC strains. CI values indicative of synergy (CI < 0.9) were observed in 42 data sets. Of those, 11 synergistic data sets (n = 8 in PV group, n = 3 in T/F IMC group; data obtained from nine different antibody combinations) with mean CI <0.9 had standard deviations that reached into the range of additivity; in Table 2 they are indicated with hatched light grey shading to distinguish them from the 5 data set for which CI values indicating additivity were obtained (medium grey shading). CI values indicative of low-level antagonism were seen in 3 cases (dark grey shading).Figure 4

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