Brief Article
Copyright ©2012 Baishideng Publishing Group Co., Limited. All rights reserved.
World J Gastroenterol. Nov 7, 2012; 18(41): 5925-5931
Published online Nov 7, 2012. doi: 10.3748/wjg.v18.i41.5925
Effects of the viability of Lactobacillus rhamnosus GG on rotavirus infection in neonatal rats
Hanna Ventola, Liisa Lehtoranta, Mari Madetoja, Marja-Leena Simonen-Tikka, Leena Maunula, Merja Roivainen, Riitta Korpela, Reetta Holma
Hanna Ventola, Liisa Lehtoranta, Riitta Korpela, Reetta Holma, Institute of Biomedicine, Pharmacology, University of Helsinki, FI-00014 Helsinki, Finland
Mari Madetoja, Toxis Ltd Oy, Lemminkäisenkatu 14-18 C, FI-20520 Turku, Finland
Marja-Leena Simonen-Tikka, Merja Roivainen, Intestinal Viruses Unit, National Institute for Health and Welfare, FI-00271 Helsinki, Finland
Leena Maunula, Department of Food Hygiene and Environmental Health, University of Helsinki, FI-00014 Helsinki, Finland
Author contributions: Holma R, Korpela R, and Madetoja M designed the study; Holma R supervised and organized the study; Ventola H and Lehtoranta L designed and carried out the animal experiments, subsequent molecular analyses, and drafted the manuscript; Madetoja M designed and carried out the animal experiments; Simonen-Tikka ML participated in the rotavirus-PCR analysis; Maunula L cultivated and provided the rotavirus strain, and participated in drafting the manuscript; Roivainen M participated in the study design, and helped to develop the rotavirus-PCR method; all authors read and approved the final manuscript.
Supported by Valio Ltd and the Finnish Funding Agency of Technology and Innovation; The Foundation for Nutrition Research has financially contributed to Liisa Lehtoranta’s doctoral studies
Correspondence to: Dr. Reetta Holma, Institute of Biomedicine, Pharmacology, University of Helsinki, PO Box 63, FI-00014 Helsinki, Finland. reetta.holma@helsinki.fi
Telephone: +358-9-19124366 Fax: +358-9-19125364
Received: January 13, 2011
Revised: February 28, 2012
Accepted: March 20, 2012
Published online: November 7, 2012
Abstract

AIM: 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).

CONCLUSION: Both live and dead GG have beneficial effects in RV infection. GG may increase RV clearance from the body and reduce colon swelling.

Keywords: Diarrhea, Lactobacillus rhamnosus GG, Neonatal rat, Rotavirus, Viability