After receiving her early education there, she won a Colombo Plan Scholarship to La Trobe University, Australia for her tertiary education where she graduated with a degree in Microbiology in 1979. She then won a La Trobe University research scholarship to complete her PhD on “Genetic and molecular analysis of plasmid RP1: Interactions with prophage B3 and aspects of conjugal transmission” in 1983 under the supervision of Dr Vilma A. Stanisich.
She joined the Universiti Putra Malaysia (then known as Universiti Pertanian Malaysia) as a lecturer in 1983. It was then that her research interest progressed from microbial genetics to the molecular biology of the Newcastle disease virus (NDV) and other paramyxoviruses. After working as a post-doctoral Research Associate at the University of Newcastle-upon-Tyne, UK she began to develop her research on NDV by collaborating with Professor Abdul Latif Ibrahim. She was promoted to Associate Professor in 1994 and became a full Professor in 2001. She is currently the Deputy Vice Chancellor for Academic and International Affairs at UPM.
In recognition of her teaching and research in microbiology, in particular on the molecular biology of NDV, she has received many awards including the 2005 Carlos J Finlay Prize for microbiology by UNESCO and the National Young Scientist Award in 1990. She was also selected by the Houghton Trust and invited to deliver the Third Houghton Lecture at the XIIth World Veterinary Poultry Association (WVPA) Congress in 2002 for her contributions to the poultry industry. Some of her work included the determination of the first complete sequence of the L gene, epitope mapping of the haemagglutinin-neuraminidase and fusion proteins, and the molecular biology of local NDV strains including the challenge strain AF2240 and a heat stable vaccine strain V4 (UPM). Pursuing the vaccine research, she is currently investigating the potential of developing recombinant vaccines in various expression systems using reversed genetics as well as nanobiotechnology. Furthermore, she is studying the molecular biology of NDV through phage display technology and protein-virus interactions in order to develop specific antiviral drugs, diagnostic tests, characterise the virus receptor(s) and study the assembly and infection of NDV in cancer cells. Her other research interests include poultry viruses such as infectious bronchitis, infectious bursal disease and chicken anaemia viruses. Her research has also extended beyond viruses and poultry, to include human viruses such as the Nipah virus and the hepatitis B virus as well as Escherichia coli, Campylobacter jejuni, Lactococcus lactis and genetic diversity of Asian water buffalo and fresh water fish.
Her work is supported by many research funds including one from the Third World Academy of Sciences (TWAS). Her current research is on the development of novel therapeutic and diagnostic reagents from NDV. She has over 100 publications in refereed journals and well over 290 papers in proceedings and abstracts. In addition, she has filed several patents and trade marks, and currently holds a US patent. Some of the work include an RT-PCR-ELISA test was developed for mass screening of NDV in chickens; the NP protein of NDV has been genetically modified to act as a molecular carrier for drug and vaccine delivery systems, and an anti-NDV peptide was developed to inhibit NDV replication in vivo as well as distinguish between chickens infected with the virulent field strains from the vaccinated ones.
Together with her colleagues, she has supervised over 100 postgraduate students, 75 of whom have graduated. She is also active in several local and international professional societies. She is one of the founding members of the Malaysian Society for Molecular Biology and Biotechnology, and she is also active in the Malaysian Society for Molecular Biology and Biochemistry, Malaysian Society for Microbiology and Malaysian Applied Biology Society. She has served as a member of several Editorial Boards and as a member of the panel of reviewers for several journals. She was formerly the Chief Editor for the Asia-Pacific Journal for Molecular Biology and Biotechnology. She is also a member of the Malaysian Genetic Modification Advisory Committee. At the international level, she is a member of the American Society for Microbiology (USA), Society for General Microbiology (UK) and Third World Organisation for Women in Science (TWOWS).
Prof. Khatijah was elected as a Fellow of the IAS in 2008.