Sabra Klein is an American microbiologist who is a Professor of Molecular Microbiology and Immunology at the

Johns Hopkins Bloomberg School of Public Health The Johns Hopkins Bloomberg School of Public Health is the public health graduate school of Johns Hopkins University, a private research university in Baltimore, Maryland. As the second independent, degree-granting institution for research in epi ...

. Her research considers how

sex Sex is the trait that determines whether a sexually reproducing animal or plant produces male or female gametes. Male plants and animals produce smaller mobile gametes (spermatozoa, sperm, pollen), while females produce larger ones ( ova, of ...

and

gender Gender is the range of characteristics pertaining to femininity and masculinity and differentiating between them. Depending on the context, this may include sex-based social structures (i.e. gender roles) and gender identity. Most cultures ...

impact the

immune system The immune system is a network of biological processes that protects an organism from diseases. It detects and responds to a wide variety of pathogens, from viruses to parasitic worms, as well as cancer cells and objects such as wood splint ...

. During the

COVID-19 pandemic The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identi ...

, Klein investigated why men and women have different COVID-19 outcomes.

Early life and education

Klein earned her bachelor's degree in psychology at

Randolph–Macon College Randolph–Macon College is a private liberal arts college in Ashland, Virginia. Founded in 1830, the college has an enrollment of more than 1,500 students. It is the second-oldest Methodist-run college in the country, and the oldest in continu ...

and graduated in 1992. She moved to the

University of Georgia , mottoeng = "To teach, to serve, and to inquire into the nature of things.""To serve" was later added to the motto without changing the seal; the Latin motto directly translates as "To teach and to inquire into the nature of things." , establ ...

for her graduate studies, where she studied the impact of prenatal stress on the immune systems of rodents. She completed her doctoral research in behavioural neuroscience at

, where she studied the sex and species differences in rodent immune function. Klein was a postdoctoral fellow in the laboratory of Gregory E. Glass.

Research and career

Klein investigated the mechanisms that allows rodents to carry

hantaviridae ''Hantaviridae'' is a family of viruses in the order ''Bunyavirales''. It is named for the Hantan River area in South Korea where an early outbreak of one of its species was observed. Taxonomy * '' Actantavirinae'' ** '' Actinovirus'' * '' Aga ...

. To do this she monitored the immune response of

Norway rat The brown rat (''Rattus norvegicus''), also known as the common rat, street rat, sewer rat, wharf rat, Hanover rat, Norway rat, Norwegian rat and Parisian rat, is a widespread species of common rat. One of the largest muroids, it is a brown o ...

s infected with Seoul orthohantavirus and showed that they have high numbers of regulatory

T cell A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...

s. By inactivating regulatory T cells and monitoring the presence of

orthohantavirus ''Orthohantavirus'' is a genus of single-stranded, enveloped, negative-sense RNA viruses in the family '' Hantaviridae'' within the order ''Bunyavirales''. Members of this genus may be called orthohantaviruses or simply hantaviruses. Orthohantav ...

in the rodents, Klein showed that

viruses achieve persistence by exploiting these regulatory T cells. This allows rodents to maintain hantaviridae infections. Her research may help us better predict how hantaviridae they can be transmitted to humans. Whilst she started her academic career in

neuroscience Neuroscience is the scientific study of the nervous system (the brain, spinal cord, and peripheral nervous system), its functions and disorders. It is a multidisciplinary science that combines physiology, anatomy, molecular biology, developme ...

, Klein became more interested in immune system function. She is particularly interested in the differences between men and women's immune systems, and how they handle infectious diseases. Klein identified that the

X chromosome The X chromosome is one of the two sex-determining chromosomes (allosomes) in many organisms, including mammals (the other is the Y chromosome), and is found in both males and females. It is a part of the XY sex-determination system and XO sex ...

was encoded with several genes that control the immune response. She believes that

estrogen Estrogen or oestrogen is a category of sex hormone responsible for the development and regulation of the female reproductive system and secondary sex characteristics. There are three major endogenous estrogens that have estrogenic hormonal ac ...

alters the response of immune cells, encouraging it to start making proteins and start or stop an inflammatory response. Whilst this stronger immune response can clear viruses faster in women, it can also cause

immunopathology Immunopathology is a branch of medicine that deals with immune responses associated with disease. It includes the study of the pathology of an organism, organ system, or disease with respect to the immune system, immunity, and immune responses. In ...

. It is known that hormones impact the progression of influenza, and in 2009 Klein was commissioned by the

World Health Organization The World Health Organization (WHO) is a specialized agency of the United Nations responsible for international public health. The WHO Constitution states its main objective as "the attainment by all peoples of the highest possible level of ...

to understand how sex, gender and pregnancy impact the outcomes of influenza infection. In 2018 Klein was awarded $8 million from the

National Institutes of Health The National Institutes of Health, commonly referred to as NIH (with each letter pronounced individually), is the primary agency of the United States government responsible for biomedical and public health research. It was founded in the late ...

to better understand how biological sex and age impact the efficacy of influenza vaccinations. As part of this research, Klein created a mechanistic study into how genetic and hormonal factors impacted mouse immunity. She demonstrated that biological sex impacted the efficacy of vaccinations, showing that female mice who received the

2009 flu pandemic vaccine The 2009 swine flu pandemic vaccines were influenza vaccines developed to protect against the pandemic H1N1/09 virus. These vaccines either contained inactivated (killed) influenza virus, or weakened live virus that could not cause influenza. Th ...

produced more antibodies than male mice. Her findings may indicate that men need a different dose or more frequent influenza vaccination boosts to women. During the

, Klein became interested in the differences between how men and women responded to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-Cov-2). It is well documented that men have worse

COVID-19 Coronavirus disease 2019 (COVID-19) is a contagious disease caused by a virus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The first known case was identified in Wuhan, China, in December 2019. The disease quickly ...

outcomes to women. Klein has indicated that this biological sex dependent disparity in outcomes is common to many viral infections that impact the respiratory tract. Both she and

Angela Rasmussen Angela Lynn Rasmussen is an American virologist at the Vaccine and Infectious Disease Organization at the University of Saskatchewan in Canada. Education and early career During graduate school, Rasmussen worked in the laboratory of Vincent ...

have argued that there are behavioural as well as biological reasons that men are so susceptible to COVID-19. In 2022, she was elected a Fellow of the American Association for the Advancement of Science.

Selected publications

* * *

Personal life

Klein is married to

Drew Maloney Andrew Kerwin Maloney (born March 30, 1969) is a former senior U.S. government official and government affairs executive and the president and Chief Executive Officer of the American Investment Council, an industry association for private-equity ...

. In 2010 the couple created the Klein-Maloney Fellowship for Women in the Sciences.

References

{{DEFAULTSORT:Klein, Sabra Living people Year of birth missing (living people) Women microbiologists American microbiologists Johns Hopkins University faculty Johns Hopkins University alumni COVID-19 researchers Fellows of the American Academy of Microbiology Fellows of the American Association for the Advancement of Science