Studies in a Murine Model Confirm the Safety of Griffithsin and Advocate Its Further Development as a Microbicide Targeting HIV-1 and Other Enveloped Viruses

Kouokam, Joseph Calvin; Lasnik, Amanda B.; Palmer, Kenneth E.

here was no statistically significant difference between PBS-treated cells (5.0% ± 0.5%) and those cultured in the presence of GRFT, 1 µM (5.9% ± 1.1%) or 4 µM (6.5% ± 1.0%) ( Figure 3A ). In contrast, 25.8% ± 0.3% and 71.7% ± 8.1% cells expressed CD25 after treatment with PHA and ConA, respectively ( Figure 3A ). Similar observations were made for the surface activation marker CD69. As shown in Figure 3B , treatment with 1 and 4 µM GRFT resulted in 3.7% ± 0.1% and 3.9% ± 1.0% CD4+CD69+ PBMCs, respectively, values not significantly different from that obtained for PBS-treated cells (2.7% ± 0.4%). However, a considerable increase in the CD4+CD69+ population of mouse PBMCs was observed after treatment with 10 µg/mL PHA (12.7% ± 2.2%) and 0.37 µM ConA (20.8% ± 2.4%). In addition, the total percentage of CD69+ cells was similar in unstimulated PBS treated cells (6.0% ± 1.6%), 1 µM and 4 µM GRFT (8.3% ± 1.7% and 8.6% ± 3.2%, respectively) as shown in Figure 3B . mPBMCs stimulated with 10 µg/mL PHA resulted in 30% CD69+ cells whereas 0.37 µM ConA treatment yielded about 70% cells expressing CD69 ( Figure 3B ). Taken together, these findings indicated a good safety profile in mPBMCs. Furthermore, we evaluated the percentages of cells expressing two known PBMC cellular activation markers, CD25 and CD69. In PBS-treated cells, 3.0% ± 0.2% of cells were CD4+CD25+ ( Figure 3A ). mPBMCs incubated in the presence of 1 and 4 μM GRFT showed similar values for CD4+/CD25+ cells with 3.7% ± 0.23% and 3.8% ± 0.4%, respectively, whereas these amounts were markedly increased by 87 nM, i.e., 10 μg/mL PHA (11.0% ± 2.3%) and 0.37 μM ConA (16.7% ± 4.8%), as shown in Figure 3A . When total numbers of cells expressing CD25 were compared, there was no statistically significant difference between PBS-treated cells (5.0% ± 0.5%) and those cultured in the presence of GRFT, 1 μM (5.9% ± 1.1%) or 4 μM (6.5% ± 1.0%) ( Figure 3A ). In contrast, 25.8% ± 0.3% and 71.7% ± 8.1% cells expressed CD25 after treatment with PHA and ConA, respectively ( Figure 3A ). Similar observations were made for the surface activation marker CD69. As shown in Figure 3B , treatment with 1 and 4 μM GRFT resulted in 3.7% ± 0.1% and 3.9% ± 1.0% CD4+CD69+ PBMCs, respectively, values not significantly different from that obtained for PBS-treated cells (2.7% ± 0.4%). However, a considerable increase in the CD4+CD69+ population of mouse PBMCs was observed after treatment with 10 μg/mL PHA (12.7% ± 2.2%) and 0.37 μM ConA (20.8% ± 2.4%). In addition, the total percentage of CD69+ cells was similar in unstimulated PBS treated cells (6.0% ± 1.6%), 1 μM and 4 μM GRFT (8.3% ± 1.7% and 8.6% ± 3.2%, respectively) as shown in Figure 3B . mPBMCs stimulated with 10 μg/mL PHA resulted in 30% CD69+ cells whereas 0.37 μM ConA treatment yielded about 70% cells expressing CD69 ( Figure 3B ). Taken together, these findings indicated a good safety profile in mPBMCs.