Treponema pallidum has humans as the reservoir, can cross the placenta, has not been grown in artificial media, and is transmitted by direct sexual contact. Which of the following statements is correct?
1) Humans are not the reservoir for Treponema pallidum
2) Treponema pallidum cannot cross the placenta
3) Treponema pallidum has been grown in artificial media
4) Treponema pallidum is not transmitted by direct sexual contact
5) All of the choices are correct
