Canadian drugmaker Tekmira Pharmaceuticals Corp. has begun limited manufacturing of a drug targeting the Ebola-Guinea virus.

Tekmira said Tuesday that the product would be available by early December but did not specify how many doses it was making.

Tekmira has completed the design of a modified RNAi (ribonucleic acid interference) drug that targets the Ebola-Guinea variant, the virus responsible for the worst outbreak on record. The drug, TKM-Ebola, works by preventing the virus from replicating.

Tekmira's application to U.S. regulators for TKM-Ebola remains on partial clinical hold, with the issue expected to be resolved within the quarter.

The European Medicines Agency said on Monday it was ready to offer Ebola treatments and vaccines the benefits of "orphan" drug status — including extended market exclusivity — in a bid to encourage their development.

Initial clinical trials of Ebola vaccines from GlaxoSmithKline and NewLink Genetics are already under way, the World Health Organization said on Tuesday.

Mapp Biopharmaceutical gave its experimental Ebola treatment ZMapp to American medical workers Dr. Kent Brantly and Nancy Writebol, who recovered after contracting Ebola in Liberia, and to at least one Spanish priest, who died. Mapp said it had begun manufacturing the drug using traditional methods, which would allow the company to produce more of the drug so that human testing can be carried out.

In September, U.S. and Canadian regulators authorized the use of TKM-Ebola in patients who have confirmed or suspected infections from the virus.