Combine yeast, sugar and ½ cup warm water and let stand for about 5 minutes. Whisk in orange juice, olive oil, 2 eggs, honey and salt. Blend in mixer with dough hook adding about 1 cup of flour at a time to form smooth dough. Beat well after each addition. Beat on medium speed about 5 minutes. Turn dough out onto floured surface and knead for about 2 minutes. The dough should be sticky to the touch.
Place dough in lightly oiled large bowl. Cover dough with plastic wrap until doubled in volume, 1-2 hours. Punch down dough. Cover again and let rise another hour. Punch dough down again.
Grease a 9-inch pie pan or baking sheet. Turn dough onto floured surface and divide into 4 equal portions. Roll each piece into ropes. Arrange ropes in a crisscross pattern and braid into a round. Place braided round in the pie pan or on the baking sheet. Whisk remaining egg, brush dough top and sides and let rise again until almost doubled, approximately 30 minutes.
Preheat oven to 375 degrees. Brush dough again with egg then sprinkle with poppy seeds. Bake 30-40 minutes until golden and sounds hollow. Transfer to rack and cool completely.