Karen Midthun

Human milk mucin inhibits rotavirus replication and prevents experimental gastroenteritis

Acute gastrointestinal infections due to rotaviruses and other enteric pathogens are major causes of morbidity and mortality in infants and young children throughout the world. Breast-feeding can reduce the rate of serious gastroenteritis in infants; however, the degrees of protection offered against rotavirus infection vary in different populations. The mechanisms associated with milk-mediated protection against viral gastroenteritis have not been fully elucidated. We have isolated a macromolecular component of human milk that inhibits the replication of rotaviruses in tissue culture and prevents the development of gastroenteritis in an animal model system. Purification of the component indicates that the antiviral activity is associated with an acidic fraction (pI = 4.0-4.6), which is free of detectable immunoglobulins. Furthermore, high levels of antiviral activity are associated with an affinity-purified complex of human milk mucin. Deglycosylation of the mucin complex results in the loss of antiviral activity. Further purification indicated that rotavirus specifically binds to the milk mucin complex as well as to the 46-kD glycoprotein component of the complex. Binding to the 46-kD component was substantially reduced after chemical hydrolysis of sialic acid. We have documented that human milk mucin can bind to rotavirus and inhibit viral replication in vitro and in vivo. Variations in milk mucin glycoproteins may be associated with different levels of protection against infection with gastrointestinal pathogens.

The Safety and Immunogenicity of a Human Immunodeficiency Virus Type 1 (HIV-1) Recombinant gp160 Candidate Vaccine in Humans

Objective: To evaluate the safety and immunogenicity of a human immunodeficiency virus type 1 (HIV-1) recombinant envelope glycoprotein (rgp160) candidate vaccine in humans. Subjects: Healthy adult...

Comparison of the amino acid sequences of the major neutralization protein of four human rotavirus serotypes

We sequenced the gene coding for the major neutralizing protein (VP7) from eight human rotavirus strains representing serotype 1, 2, 3, or 4. In addition, the corresponding gene of the rhesus rotavirus vaccine strain MMU 18006 (serotype 3) was sequenced. Comparative analyses of their deduced amino acid sequences revealed an overall 15-29% divergence in the VP7 proteins that define four different rotavirus serotypes and confirmed the presence of six discrete regions of clustered sequence divergence (amino acids 39-50, 87-101, 120-130, 143-152, 208-221, and 233-242). When the same regions were compared among rotaviruses belonging to the same serotype, a high degree of homology (91-99%) was detected. These observations indicate that differences in the serotype specificity among rotaviruses are the result of a high degree of sequence divergence in several discrete regions of the VP7 gene and that these regions are highly conserved within a given serotype.

Safety and immunogenicity of live attenuated human-bovine (UK) reassortant rotavirus vaccines with VP7-specificity for serotypes 1, 2, 3 or 4 in adults, children and infants.

Live rotavirus vaccine candidates representing VP7 serotypes 1, 2, 3 or 4 derived by reassortment between bovine UK rotavirus and human rotavirus strains D, DS-1, P or ST3 were evaluated for safety and immunogenicity in adults, children and infants. Infection was defined by evidence of rotavirus shed in stools or a 4-fold or greater increase in serum rotavirus-specific IgA or IgG ELISA or plaque reduction neutralization antibody. A single oral dose (10(5.3) or 10(5.8) pfu) of reassortant virus was well tolerated and infected most infants: 10/20 (50%) by D x UK; 9/11 (82%) by DS-1 x UK; 8/10 (80%) by P x UK and 13/14 (93%) by ST3 x UK. All 14 infants given two doses of D x UK were infected. These findings demonstrating satisfactory levels of attenuation, safety, infectivity and immunogenicity of each reassortant in infants warrant additional studies of a candidate vaccine containing these four strains.

Strategies for the development of a rotavirus vaccine against infantile diarrhea with an update on clinical trials of rotavirus vaccines.

It is an honor and privilege to participate in this Symposium on “The Immune Response to Viral Infections” in this historic, celebrated city of countless renowned splendors where artistic and intellectual giants such as Leonardo da Vinci, Michelangelo, Dante, Machiavelli, Giotto, Botticelli, Galileo, Cellini, The Medici and the navigator Amerigo Vespucci exerted such profound influence, for it was here that Florentine scholars, painters, architects and craftsmen began the Renaissance. Although this pinnacle of human expression was unleashed with such intensity beginning some 500 years ago, thus laying the foundation for striking artistic, cultural and intellectual achievements, it is ironic that this energy did not successfully pollinate concurrently the domain of medicine since progress in discovering the etiologic agents of various scourges of humankind and elucidation of means to eliminate them were not forthcoming for centuries. Indeed, the mortality rate in the 15th century was quite high as documented in the Florentine dowry records of under one year to 19 year old females, with the highest rate occurring, by far, in the less than 5 year-old age group (Morrison et al., 1977).

Safety profile and immunogenicity of an inactivated vaccine derived from an attenuated strain of hepatitis A.

To determine the safety and immunogenicity of an inactivated hepatitis A vaccine, 56 healthy adult volunteers were randomly assigned to receive an intramuscular injection of 6.3, 12.5 or 25 ng of inactivated hepatitis A vaccine or placebo at 0, 2 or 4, and 24 weeks. Adverse reactions occurred with similar frequency in vaccine and placebo recipients and consisted primarily of pain or tenderness at the injection site. By 4 weeks after a single 6.3, 12.5 or 25 ng injection, seven, nine and ten out of ten vaccinees, respectively, had antibody detectable by a HAV AB assay modified to increase its sensitivity tenfold. All vaccinees had antibodies detectable by this assay within 2 weeks of their second inoculation. Geometric mean antibody levels increased with higher doses of vaccine (p = 0.05). Neutralizing antibody was detected within 4 weeks of a single inoculation in all vaccinees. Neutralizing antibody was detected after the third inoculation at dilutions of greater than or equal to 1:2048 in all 12.5 and 25 ng vaccinees. All 19 vaccinees tested at 24 months still had HAV antibodies detectable by a modified HAV AB assay. This inactivated hepatitis A vaccine appears to be well tolerated and immunogenic at doses of 6.3-25 ng. The choice of dose and vaccination schedule may depend on the rapidity with which seroconversion is desired.

Take of rhesus-human reassortant tetravalent rotavirus vaccine in breast-fed infants

Rhesus‐human reassortant tetravalent rotavirus vaccine at a titer of 4 x 104 plaque forming units was evaluated for immmunogenicity in 194 6–8‐week‐old breast‐fed Turkish infants. The vaccine was administered orally as a single dose following either a meal of breast milk or 30 ml of sodium bicarbonate‐buffered soy milk formula. Four‐fold or greater responses in rotavirus IgA ELISA antibody were detected in 62% and 65′% of the infants in the two groups, respectively (p= 0.62). In a smaller comparison group of non‐breast‐fed infants, an IgA response was detected in 7 of 11 (64%) cases. In all vaccinees, a serological response was detected in 72% of the initially seronegative and 47% of the initially seropositive infants (p= 0.001). We conclude that the take of rhesus‐human reassortant tetravalent rotavirus vaccine in breast‐fed infants is not compromised by breast feeding before vaccination. However, a higher titered preparation of the same vaccine may be required to improve overall immunogenicity in young infants, particularly in those with pre‐vaccination rotavirus antibody.

Safety and immunogenicity of oral tetravalent human-rhesus reassortant rotavirus vaccine in neonates

We conducted a prospective randomized double blind study to determine: (1) the safety and immunogenicity of live oral tetravalent human-rhesus rotavirus reassortant vaccine in neonates; and (2) whether a second dose at the age of 6 to 8 weeks enhances the immunogenicity. Two hundred forty healthy neonates were enrolled and received vaccine (183) or placebo (57) on the second day of life. At the age of 6 to 8 weeks 133 received placebo and 88 received a second dose of vaccine. Medical events were noted within 10 days from vaccine administration in 6 of 183 (3.3%) vaccine recipients vs. 0 of 57 placebo recipients (P = 0.34) after the first dose and in 8 of 88 (9%) vs. 4 of 133 (3%) after the second dose (P = 0.069); none was severe and all were of short duration. Seroresponse of any type (detectable IgA or 4-fold increase of titer to rhesus rotavirus was 9% for the placebo, vs. 52 and 46% for those who received one and two doses of vaccine, respectively. However, neutralizing antibodies against human serotypes 1, 2 and 3 were not raised successfully in vaccinated infants when compared with placebo recipients. The same pattern was found when geometric mean titers were compared. Vaccine take was better when cord blood titers were low. At the age of 1 year the vaccinees had more often high titers for antirhesus rotavirus antibodies (> 640) than the placebo recipients (49% vs. 0%; P < 0.001). NO difference was found between the groups in neutralizing antibodies to human serotypes 1, 2 and 3 rotavirus.(ABSTRACT TRUNCATED AT 250 WORDS)

Reactogenicity and antigenicity of rhesus rotavirus vaccine (MMU-18006) in newborn infants in Venezuela.

The reactogenicity and antigenicity of the rhesus rotavirus vaccine, strain MMU18006, developed at the Laboratory of Infectious Diseases (National Institute of Allergy and Infectious Diseases, National Institutes of Health) were examined in a double blind, placebo-controlled study of 40 newborn infants in Caracas, Venezuela. The children were observed for the first few days after birth in the hospital nursery and by home visits for 10 days after vaccination to detect any adverse reactions. No reactions could be attributed to the vaccine. Serologic responses to the vaccine were evaluated in paired sera obtained at birth (cord blood) and 4 weeks after vaccination. Serologic responses to the vaccine were not observed by complement fixation, neutralization or a rhesus rotavirus VP7 epitope-specific competition assay. However, such responses were found in 9 of 14 tested infants by an immunoglobulin A-specific en

Recent Advances in Development of a Rotavirus Vaccine for Prevention of Severe Diarrheal Illness of Infants and Young Children

Diarrheal diseases are an important cause of morbidity in infants and young children in developed countries and a major cause of both morbidity and mortality in this same age group in developing countriesl. The toll from diarrheal diseases in the developing countries is enormous. For example, it is estimated that in Asia, Africa, and Latin America, 3–5 billion cases of diarrhea and 5–10 million diarrhea-associated deaths occur each year2. In addition, diarrhea was ranked first among infectious diseases with regard to the number of episodes and the number of deaths in these areas of the world.