MATERIALS AND METHODS
SMV human challenge study 1 [11]: 15 healthy human subjects
were challenged with one dose of SMV inoculum, ranging from 31.7 to 3.17
× 105 genome copies quantitated by RT-qPCR [13].
Subjects remained in the hospital clinical research unit for five days
after challenge. Stool, serum, vomitus, saliva samples and clinical
information were collected daily. Subjects were also followed up on days
7, 15, 30, and 45 post-challenge for stool and serum sample collection
[11].
SMV human challenge study 2 [9]: The study consisted of four
sequential cohorts and a placebo group. In cohorts 1 through 3 (all
subjects were secretor positive), individuals per cohort were challenged
with 1.2 x 104 genome equivalent copies (GEC) (cohort
1), 1.2 x 106 GEC (cohort 2) and 1.2 x
107 GEC (cohort 3) of SMV. Cohort 4 only included
secretor-negative subjects, and they were challenged with a dose of 1.2
x 107 GEC. Subjects remained in the hospital clinical
research unit for five days after challenge. Stool, serum, vomitus,
saliva samples and clinical information were collected. Subjects were
also followed up on days 7, 15, 30, and 45 post-challenge for stool and
serum sample collection. For this secondary data analysis, a total of 33
subjects who received the SMV inoculum and completed the study [9]
were included in this study.
All the laboratory assays, including detection of anti-SMV IgG in serum,
detection of secretor status, and quantification of SMV RNA in stool
have been described previously [9, 11]. SMV infection was defined as
RNA detection in any post-challenge stool sample by RT-PCR or specific
RT-qPCR with CT values < 40 in duplicate reactions
and/or anti-SMV serum IgG conversion by ELISA in any post-challenge
serum sample vs. pre-challenge serum sample. Illness was defined as
those infected with SMV who presented with diarrhea ≥3 loose or liquid
stools or ≥300 g of loose or liquid stools in any continuous 24-h
period, or one or more vomiting episodes during the inpatient period and
with one other clinical sign or symptom such as fever, abdominal cramps,
nausea, headache, chills, fatigue, or myalgia.