Our July Researcher in Focus is Dr. Jaythoon Hassan, Senior Clinical Scientist at the National Virus Reference Laboratory (NVRL) at UCD and winner of the Laboratory Scientist of Year Award at the Irish Laboratory Awards 2020. Jaythoon is funded through the National Children’s Research Centre Paediatric Research Project Grant scheme for her project “Mumps Outbreaks in Vaccinated Populations”.
Vaccination programmes have made an enormous contribution to human health. As Jaythoon explains “Globally, life expectancy has been dramatically improved due to the reduced burden of infectious diseases and the co-morbidities associated with infection”.
Jaythoon studies Mumps: “an acute viral infection characterised by fever, swelling and tenderness of one or more salivary glands, most typically the parotid gland. Symptoms are normally not life threatening; however, complications necessitating hospitalisation may occur following mumps virus infection in approximately 10% of cases”.
The Mumps virus is spread person to person through respiratory droplets (coughing and sneezing) and is highly contagious. In a fully susceptible population, the reproductive rate (R0) of Mumps is 10-12, meaning one person with Mumps could infect 10 -12 additional individuals.
Fortunately, Mumps is a vaccine preventable disease with two doses of the MMR (Measles-Mumps-Rubella) vaccine offering the best protection against infection: “Routine childhood vaccination with measles-mumps-rubella (MMR) vaccine was introduced in the Republic of Ireland in 1988 for children between 12 to 15 months of age. In 1992, a second dose of the MMR vaccine (MMR2) was introduced for children 10 to 14 years of age; however, the age for MMR2 was subsequently reduced in 1999 to 4 to 5 years of age, following primary-school measles outbreaks”.
Since its introduction, the MMR vaccination program has resulted in a dramatic decrease in cases of Mumps. However, before the start of the COVID-19 crisis, Ireland was in the midst of a large outbreak, with close to 5000 cases of Mumps reported between August 2018 and early 2020, predominantly in adolescents and young adults. The containment measures introduced to control the spread of COVID-19 have also resulted in a decline in the number of cases of Mumps.
Jaythoon’s project aims to understand how Mumps outbreaks continue to occur in countries like Ireland where there is high uptake of the MMR vaccine: “This research project aims to understand why in a highly vaccinated population like Ireland some individuals can be re-infected with mumps whereas others are protected. There is a need by scientists to continue developing and optimising vaccination protocols. An urgent healthcare priority is the optimal use of our existing vaccines as well as the development of new techniques to determine a level of protective immunity to infectious diseases”.
Typically, a person’s level of protection against a virus following vaccination is based on the levels of virus neutralising antibodies in the blood. These neutralising antibodies recognise and bind to specific parts of the virus and block the infection.
Recent research suggests that although the presence of these antibodies implies immunity, this may not be the case: “While neutralising antibody titres are considered the “gold standard” for vaccine efficacy studies, antibody titre determination alone is often an inadequate predictor of protective immunity as observed in the recent outbreaks in individuals who had detectable IgG (a type of antibody) specific to mumps virus”.
In addition to their neutralising activity, antibodies also help fight viral infections in other ways. For example, immune cells recognise and destroy antibody coated cells that express viral antigens on their surface, a process called antibody-dependent cellular cytotoxicity.
Jaythoon and her research team (postdoctoral researcher Dr. Anna Connell) are measuring and comparing the neutralising activity and extra neutralising activity of mumps specific antibodies in individuals who have received the MMR vaccine, individuals who were diagnosed with Mumps despite receiving the MMR vaccine, and individuals who were diagnosed with Mumps but never received the MMR vaccine: “There is only limited information in the literature in relation to the extra-neutralising capability of mumps specific IgG. This research project will analyse the neutralising and extra-neutralising humoral fingerprint”.
This will allow Jaythoon and her team to determine if a more in-depth analysis of Mumps specific antibodies provides a better indicator of an individual’s level of protection following vaccination and help identify individuals who might be at risk of infection despite being vaccinated against Mumps: “This may offer a unique approach to identify potential markers of the serological response against mumps and inform the selection of the most appropriate laboratory tests to indicate antibody mediated protection against mumps. Furthermore, detailed evaluation of key functional properties of mumps-specific antibodies may lead to the discovery of a correlate of protection which remains elusive to date”.
Additional information on Jaythoon research can be found through the following links:
NVRL website: https://nvrl.ucd.ie/