[DemonRaven]

I know that many if not all chatbots and virtual assistants are a form of natural language processing but are there any chatbots/virtual assistants designed using Neural networks?

For those that don't know:
 

Neural networks are a set of algorithms, modeled loosely after the human brain, that are designed to recognize patterns. They interpret sensory data through a kind of machine perception, labeling or clustering raw input.

from https://skymind.ai/wiki/neural-network

Natural language processing (NLP) is a branch of artificial intelligence that helps computers understand, interpret and manipulate human language. NLP draws from many disciplines, including computer science and computational linguistics, in its pursuit to fill the gap between human communication and computer understanding.

https://www.sas.com/en_us/insights/analytics/what-is-natural-language-processing-nlp.html

[AndyGoode]

I don't know the answer to your question, but I know that neural networks are mostly the wrong tool for chatbots. Neural networks map patterns to patterns, usually in a somewhat continuous way (meaning they usually add interpolated points), so neural networks aren't good for dealing with discrete, symbolic entities like strings of text, which is what words are. You could use neural networks in a limited fashion for some chatbot tasks, like deciding which word is better suited for an occasion, or which way to steer the conversation, but those are rather optional side operations rather than the core of the reasoning system.

(p. 36)
Classical AI
techniques are best suited for natural language processing, planning, or explicit reasoning,
whereas neural networks are best suited for lower-level perceptual processes, pattern
matching, and associative memories.

Haykin, Simon. 1994. Neural Networks: A Comprehensive Foundation. New York, New York: Macmillan College Publishing Company.