pip install using proxy in a virtual environment

I work on a Ubuntu VM in my company's laptop which uses proxy server for coecting to inteet. After some research I found out how to install modules using pip install with proxy. For example, using this command I can install my virtualenv module:

sudo pip install --proxy=http://user:pass@<proxy_address>:<portnumber> virtualenv

However, after creating a virtual environment folder, activate it and then install a module using this pip command:

pip install --proxy=http://user:pass@<proxy_address>:<portnumber> pyperclip

I get this error:

 Retrying (Retry(total=4, coect=None, read=None, redirect=None)) after coection broken by 'ProxyError('Caot coect to proxy.', OSError('Tuel coection failed: 407 Proxy Authentication Required',))': /simple/pyperclip/

If I use sudo, pip can download and install the module, but in system global package instead of in my virtual environment. It seems for me a permission issues in my Ubuntu and its proxy setting.

How can I tackle this issue, so that I can install a module locally in my virtualenv?

Thanks