Catarina’s move sparked outrage across the globe, with many claiming she was little more than a prostitute.
She also caused controversy when she revealed she would be followed every step of the way by an Australian crew for a documentary film called Virgins Wanted.
But she said: ‘I saw this as a business. I have the opportunity to travel, to be part of a movie and get a bonus with it.
‘If you only do it once in your life then you are not a prostitute, just like if you take one amazing photograph it does not automatically make you a photographer.
The auction is just business, I’m a romantic girl at heart and believe in love. But this will make a big difference to my area,’ she told Folha newspaper.
Catarina will be ‘delivered’ to her buyer on board a plane between Australia and the U.S. – being interviewed before and after the sexual act.
The intercourse itself will not be filmed and Natsu will retain a right to be anonymous, without his picture appearing in the media.
Sex toys will be banned from use and a condom will be compulsory, with Catarina saying she was prepared to prove to any sceptics that she has not had sex before.
Natsu will be tested for sexually transmitted diseases prior to the encounter.
A male virgin called Alexander, who is also being followed as part of director Justin Selsey’s documentary, sold for $3,000 to a Brazilian woman called Nene B.
Catarina previously said she wanted to plough the money – $20,000 and 90 per cent of the final auction sale price – into a non-governmental organisation which will construct modern houses in her southern home state of Santa Catarina.
She signed up to the project two years ago when she saw an advert by Thomas Williams Productions looking for a virgin to film.