FORM 6-K

                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                        Report of Foreign Private Issuer

                    Pursuant to Rule 13s - 16 or 15d - 16 of
                       the Securities Exchange Act of 1934

                         For the month of November 2005


                                   Acambis plc
                 (Translation of registrant's name into English)

                           Peterhouse Technology Park
                                100 Fulbourn Road
                                Cambridge CB1 9PT
                                     England

                    (address of principal executive offices)

    (Indicate by check mark whether the registrant files or will file annual
                 reports under cover of Form 20-F or Form 40-F

                         Forms 20-F X     Form 40-F

  Indicate by check mark whether the registrant by furnishing the information
     contained in this Form also thereby furnishing the information to the
                Commission pursuant to Rule 12g3-2(b) under the
                       Securities Exchange Act of 1934).

                              Yes       No X

 (if "Yes" is marked, indicate below the file number assigned to the registrant
                   in connection with Rule 12g3-2(b): 82- ).




Enclosure:

Research Update




Acambis achieves major milestone in JE vaccine development with start of pivotal
Phase lll clinical testing


Cambridge, UK and Cambridge, Massachusetts - 15 November 2005 - Acambis plc's ("
Acambis") (LSE: ACM, NASDAQ: ACAM) programme to develop a second-generation,
single-dose vaccine against Japanese encephalitis ("JE") has achieved a major
milestone with the start of pivotal Phase III trials.

The multi-centre trials are taking place in Australia under a Clinical Trial
Exemption licence issued by the Australian Therapeutic Goods Administration and
in the US under a US Food and Drug Administration Investigational New Drug
application.

The two trials, together totalling more than 2,800 healthy adult subjects, have
been designed to provide comprehensive safety data and to test the
non-inferiority of ChimeriVax-JE to JE-VAX(R), a licensed JE vaccine, by
statistical comparison of immunogenicity. The efficacy study, which will enrol
around 800 subjects, will also test clinical consistency of three
commercial-scale batches of ChimeriVax-JE manufactured in-house at Acambis'
Canton, MA facility. The remaining 2,000 subjects will participate in the safety
study. Acambis remains on track to submit a product licence application for
ChimeriVax-JE for travellers and endemic populations in the first half of 2007.

On 8 November, Acambis announced that it had established an agreement with
Bharat Biotech International Limited ("Bharat Biotech") for the manufacture and
marketing of ChimeriVax-JE in India. Bharat Biotech's Hyderabad-based
manufacturing plant is the largest in the Asia-Pacific region and it has an
established sales force and distribution network serving India and surrounding
countries. In parallel with the Phase III trials in Australia and the US,
Acambis aims to conduct clinical trials in India with a view to submitting a
product licence application for ChimeriVax-JE for populations where the disease
is endemic.

There is a global public health need for a single-dose, convenient and
affordable vaccine against JE, a need that is particularly significant in
endemic regions where such a vaccine could represent a major contribution to
preventing JE in children.

Gordon Cameron, Chief Executive Officer of Acambis, said:

"ChimeriVax-JE is an important product opportunity for Acambis - and today's
news marks a critical milestone - but it's even more important to those who live
with the threat of the JE virus. There is an urgent need for an improved,
single-dose, cost-effective vaccine against JE and with the launch of Phase lll
testing of our vaccine we are moving ever closer to meeting this need."



Enquiries:

Acambis plc
Gordon Cameron, Chief Executive Officer
David Lawrence, Chief Financial Officer
Lyndsay Wright, VP, Communications and IR
Tel +44 (0) 1223 275 300

Financial Dynamics
David Yates/Davina Langdale
Tel +44 (0) 20 7831 3113



About Acambis

Acambis is a leading developer of vaccines to prevent and treat infectious
diseases. Recognised internationally as the leading producer of smallpox
vaccines, Acambis is developing an investigational smallpox vaccine, ACAM2000,
and is manufacturing emergency-use stockpiles of this investigational vaccine
for the US Government and other governments around the world. It is also
developing an attenuated smallpox vaccine, MVA3000, under contracts with the US
National Institutes of Health. Acambis is establishing a travel vaccines
franchise through its US-based subsidiary Berna Products Corporation, which
markets Vivotif(R), the world's only licensed oral typhoid vaccine, in North
America. Acambis has other potential travel vaccines in development and is also
developing an investigational vaccine against the West Nile virus, which has
spread to 48 US States in the last six years.

Acambis is based in Cambridge, UK and Cambridge, Massachusetts, US. Its primary
listing is on the London Stock Exchange (ACM) and its shares are listed in the
form of American Depositary Receipts on NASDAQ (ACAM). More information is
available at www.acambis.com.



"Safe Harbor" statement under the Private Securities Litigation Reform Act of
1995:

The statements in this news release that are not historical facts are
forward-looking statements that involve risks and uncertainties, including the
timing and results of clinical trials, product development, manufacturing and
commercialisation risks, the risks of satisfying the regulatory approval process
in a timely manner, the need for and the availability of additional capital. For
a discussion of these and other risks and uncertainties see "Risk management" in
the Company's 2004 Annual Report and "Risk factors" in its Form 20-F, in
addition to those detailed on the Company's website and in the Company's filings
made with the Securities and Exchange Commission from time to time. These
forward-looking statements are based on estimates and assumptions made by the
management of Acambis and are believed to be reasonable, though are inherently
uncertain and difficult to predict. Actual results or experience could differ
materially from the forward-looking statements.





                                      SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the 
registrant Peptide Therapeutics Group has duly caused this report to be
signed on its behalf by the undersigned, thereunto duly authorized.



Date: 15 November 2005                  ACAMBIS PLC


                                        By:  /s/ Lyndsay Wright
                                             Name: Lyndsay Wright
                                             Title: VP, Communications and IR.