title: Effects of the viability of Lactobacillus rhamnosus GG on rotavirus infection in neonatal rats.
abstract: OBJECTIVE
  To study the effects of live and dead Lactobacillus rhamnosus GG (GG) on rotavirus infection in a neonatal rat model.
  
  
  METHODS
  At the age of 2 d, suckling Lewis rat pups were supplemented with either live or dead GG and the treatment was continued daily throughout the experiment. At the age of 5 and 6 d the pups received oral rotavirus (RV) SA-11 strain. The pups were sacrificed at the age of 7 or 8 d by decapitation. The gastrointestinal tract was removed and macroscopic observations were done. The consistency of feces in the colon was classified using a four-tier system. RV was detected from the plasma, small intestine, colon and feces by real-time quantitative polymerase chain reaction (PCR).
  
  
  RESULTS
  In this neonatal rat model, RV induced a mild-to-moderate diarrhea in all except one pup of the RV-inoculated rats. RV moderately reduced body weight development from day 6 onwards. On day 7, after 2 d of RV infection, live and dead GG groups gained significantly more weight than the RV group without probiotics [36% (P = 0.001) and 28% (P = 0.031), respectively]. In addition, when compared with the RV control group, both live and dead GG reduced the weight ratio of colon/animal body weight to the same level as in the healthy control group, with reductions of 22% (P = 0.002) and 28% (P < 0.001), respectively. Diarrhea increased moderately in both GG groups. However, the diarrhea incidence and severity in the GG groups were not statistically significantly different as compared with the RV control group. Moreover, observed diarrhea did not provoke weight loss or death. The RV control group had the largest amount of RV PCR-positive samples among the RV-infected groups, and the live GG group had the smallest amount. Rats receiving live GG had significantly less RV in the colon (P = 0.027) when compared with the RV control group. Live GG was also more effective over dead GG in reducing the quantity of RV from plasma (P = 0.047).
  
  
  CONCLUSIONS
  Both live and dead GG have beneficial effects in RV infection. GG may increase RV clearance from the body and reduce colon swelling.
authors.affiliation: Institute of Biomedicine, Pharmacology, University of Helsinki, FI-00014 Helsinki, Finland.
authors.forename: Hanna
authors.initials: H
authors.lastname: Ventola
authors.forename: Liisa
authors.initials: L
authors.lastname: Lehtoranta
authors.forename: Mari
authors.initials: M
authors.lastname: Madetoja
authors.forename: Marja-Leena
authors.initials: ML
authors.lastname: Simonen-Tikka
authors.forename: Leena
authors.initials: L
authors.lastname: Maunula
authors.forename: Merja
authors.initials: M
authors.lastname: Roivainen
authors.forename: Riitta
authors.initials: R
authors.lastname: Korpela
authors.forename: Reetta
authors.initials: R
authors.lastname: Holma
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003106:Colon / Q000382:microbiology* / Q000821:virology; D003967:Diarrhea / Q000382:microbiology / Q000628:therapy* / Q000821:virology; D004195:Disease Models, Animal; D005243:Feces / Q000382:microbiology / Q000821:virology; D007421:Intestine, Small / Q000382:microbiology* / Q000821:virology; D052201:Lacticaseibacillus rhamnosus / Q000254:growth & development*; D050296:Microbial Viability; D051381:Rats; D011917:Rats, Inbred Lew; D012400:Rotavirus Infections / Q000382:microbiology / Q000628:therapy* / Q000821:virology; D013997:Time Factors
keywords: Diarrhea; Lactobacillus rhamnosus GG; Neonatal rat; Rotavirus; Viability