Michael Rydelnik argues that Isaiah 7:14 and related texts such as Isaiah 9 and 11 are direct prophecies of the Messiah.
Michael Rydelnik, The Messianic Hope: Is the Hebrew Bible Really Messianic? (NAC Studies in Bible & Theology; Nashville, Tennessee: B&H Publishing Group, 2010), 146-63
[Conclusion]
It appears that according to prophecy, the Messiah’s virgin birth was an essential to be believed for two reasons: First, the virgin birth was to be a major sign to confirm Messiah Jesus’ position as the messianic Son of David. If Jesus of Nazareth had a human father named Larry or Joseph, it would prove that He really was not the Messiah. No matter how good a life one could lead by believing in Jesus, it would be a sham. Following Jesus changes our lives because He truly is the Messiah.
Second, the virgin birth is in some way related to the deity of Jesus. The prediction foretells that the Messiah would be Immanuel or “God with us.” Luke, when recording the virgin birth, records the angels’ message to Mary: “The Holy Spirit will come upon you and the power of the Most High will overshadow you. Therefore, the holy One to be born will be called the Son of God” (Luke 1:35). Just as Isaiah related the virgin birth to Messiah being God with us, so Luke regards the virgin birth as the basis for Jesus’ bring the Son of God, that is, Deity. Foundational to our faith is that God became a man in order to redeem us. Without the virgin birth, we deny the doctrine of Messiah’s deity and lose the truth of His atonement.