Rotavirus isolate WI61 representing a presumptive new human serotype

Area of Science:

• Virology
• Immunology
• Pediatric Infectious Diseases

Background:

• Rotaviruses are a leading cause of severe diarrheal disease in infants and young children worldwide.
• Existing human rotavirus serotypes include 1, 2, 3, and 4, with ongoing surveillance crucial for identifying new strains.
• Gastroenteritis in infants necessitates the identification and characterization of causative viral agents.

Purpose of the Study:

• To isolate and characterize a novel human rotavirus strain from a case of infant gastroenteritis.
• To determine the antigenic relationship of the new strain to known human and animal rotaviruses.
• To investigate the potential prevalence and serological response to the novel rotavirus in the human population.

Main Methods:

• Virus isolation from stool sample of an infant with gastroenteritis.
• Cross-neutralization tests with antisera against known rotavirus serotypes.
• Antigenic determinant mapping using reassortant rotavirus studies.
• RNA genome electropherotyping to analyze viral genome segments.
• Serological surveys of human sera and commercial cow's milk for antibodies.
• Animal studies involving inoculation of newborn calves and mice.

Main Results:

• A presumptive new human rotavirus serotype, designated WI61, was isolated.
• WI61 virus was antigenically distinct from human serotypes 1-4, human 69M, and animal rotaviruses (bovine, porcine, chicken).
• Cross-reactive antigenic determinants of WI61 were localized to the vp3 surface polypeptide (gene segment 4).
• WI61 RNA genome electropherotype was detected in 5 out of 59 infant gastroenteritis cases (1983-1984).
• Neutralizing antibodies to WI61 were prevalent in Philadelphia-area adults and infants, with titers comparable to or exceeding those for serotype 1 or 3.
• Commercial cow's milk samples also contained WI61-neutralizing antibodies.
• WI61 did not cause disease in newborn calves but induced diarrhea in newborn mice.

Conclusions:

• The isolated WI61 virus represents a presumptive new human rotavirus serotype.
• The prevalence of WI61-specific antibodies suggests circulation in the human population.
• The presence of antibodies in cow's milk warrants further investigation into potential transmission routes.
• WI61 demonstrates potential pathogenicity in a mouse model, highlighting its significance in gastroenteritis research.