Mouse susceptibility to mouse hepatitis virus infection is linked to viral receptor genotype.

We have reported that the receptor for mouse hepatitis virus (MHV) expressed in MHV-susceptible BALB/c mice (MHVR1) has 10 to 30 times the virus-binding activity of the MHV receptor expressed in MHV-resistant SJL mice (MHVR2) (N. Ohtsuka, Y. K. Yamada, and F. Taguchi, J. Gen. Virol. 77:1683-1992, 1996). This fact indicates the possibility that the difference in MHV susceptibility between BALB/c and SJL mice is determined by the virus-binding activity of the receptor. To test this possibility, we have examined MHV susceptibility in mice with the homozygous MHVR1 gene (R1/R1 genotype), mice with the MHVR1 and MHVR2 genes (R1/R2 genotype), and mice with the homozygous MHVR2 gene (R2/R2 genotype) produced by cross and backcross mating between BALB/c and SJL mice. All 63 F2 and backcrossed mice with the MHVR1 gene (R1/R1 and R1/R2) were susceptible to MHV infection, and all 57 with the homozygous MHVR2 gene (R2/R2) were resistant. We have also examined the MHV receptor genotypes of several mouse strains that were reported to be susceptible to MHV infection. All of those mice had the MHVR1 gene. These results suggest the possibility that the viral receptor determines the susceptibility of the whole animal to MHV infection.     

Sendai virus infection of mice with protein malnutrition.

Sendai virus pneumonia was produced in BALB/c mice fed protein-deficient diets in an effort to understand the severity of viral pneumonia in infants in developing countries. Animals on the deficient diet became clinically malnourished, and some aspects of cellular immunity were altered. In protein-deprived animals, the 50% lethal dose of intranasally administered Sendai virus was over 1,000-fold lower, pulmonary virus titers were higher, the infection was prolonged, and lung infection was established at a lower inoculum than in normal animals.     

Gender susceptibility to chronic hepatitis C virus infection associated with interleukin 10 promoter polymorphism

Elevated levels of interleukin 10 (IL-10) were previously described for chronically hepatitis C virus (HCV)-infected patients. We determined by a sequence-specific oligonucleotide probing technique the IL-10 promoter genotypes in 286 Argentinean HCV patients grouped according to disease outcome. The GG genotype (position -1082) is known to be associated with high IL-10 production, GA is considered an intermediate producer, and AA is associated with low IL-10 production. We found an increase in frequency of the GG genotype in female patients who do not eliminate the virus (RNA(+)). In these patients, the GG frequency was 0.19, versus 0.10 in controls (P = 0.03). This association became more significant in those RNA(+) female patients with elevated hepatic transaminases (GG frequency of 0.25; P = 0.0013). Additionally, this genotype frequency was higher in noncirrhotic female patients than in controls (GG frequency for noncirrhotic female patients was 0.31; P = 0.009). In RNA(-) patients, the GA frequency was elevated compared with that in controls (GA frequency of 0.76 in RNA(-) patients versus 0.48 in controls; P = 0.01), that in all HCV patients (GA frequency of 0.43; P = 0.001), and that in RNA(+) patients (GA frequency of 0.40; P = 0.0005). We conclude that a gender effect is observed with women carrying the GG high IL-10 producer genotype. The higher levels of IL-10 present in those individuals are associated with a higher risk of an inefficient clearance of the HCV and the development of a chronic HCV infection together with a lower risk of progression to cirrhosis in female patients.     

Combined oral/nasal immunization protects mice from Sendai virus infection

Based on the concept of a common mucosal immune system wherein mucosal associated lymphocytes traffic among the various mucous membranes, the murine gastrointestinal tract was immunized with Sendai virus antigens in order to elicit a virus-specific immune response in the respiratory tract. Multiple intragastric (oral) administration of live or killed Sendai virus induced IgA and IgG antiviral antibodies in both gastrointestinal secretions and serum. When cholera toxin as an adjuvant was included along with virus, gut IgA and IgG as well as serum IgA responses were enhanced. Antiviral antibodies induced in respiratory secretions by oral killed virus plus cholera toxin, however, were variable and protection from virus challenge was not demonstrated. Significantly higher levels of respiratory antiviral antibodies were induced if immunization with oral killed Sendai virus/cholera toxin was combined with intranasal administration of small amounts of killed virus. The combined immunization also resulted in protection of both the upper and lower respiratory tracts from virus infection. Protection of the upper respiratory tract was correlated with the presence of IgA antiviral antibodies in nasal washings. On the other hand, protection of the lower respiratory tract was correlated with IgG antiviral antibodies in bronchoalveolar lavage fluids. Immunization with intranasal killed virus alone conferred partial protection to the lower respiratory tract and no protection to the upper respiratory tract. Thus, oral immunization with killed virus antigen could prime for a protective immune response in the murine respiratory tract and this protective response included IgA antibodies.     

Genetic variation for an aphid wing polyphenism is genetically linked to a naturally occurring wing polymorphism

Many polyphenisms are examples of adaptive phenotypic plasticity where a single genotype produces distinct phenotypes in response to environmental cues. Such alternative phenotypes occur as winged and wingless parthenogenetic females in the pea aphid (Acyrthosiphon pisum). However, the proportion of winged females produced in response to a given environmental cue varies between clonal genotypes. Winged and wingless phenotypes also occur in males of the sexual generation. In contrast to parthenogenetic females, wing production in males is environmentally insensitive and controlled by the sex-linked, biallelic locus, aphicarus (api). Hence, environmental or genetic cues induce development of winged and wingless phenotypes at different stages of the pea aphid life cycle. We have tested whether allelic variation at the api locus explains genetic variation in the propensity to produce winged females. We assayed clones from an F2 cross that were heterozygous or homozygous for alternative api alleles for their propensity to produce winged offspring. We found that clones with different api genotypes differed in their propensity to produce winged offspring. The results indicate genetic linkage of factors controlling the female wing polyphenism and male wing polymorphism. This finding is consistent with the hypothesis that genotype by environment interaction at the api locus explains genetic variation in the environmentally cued wing polyphenism.     

Treatment with monoclonal anti-CD3 antibody protects against lethal Sendai virus infection by induction of natural killer cells

C57BL/6 mice are protected from a lethal pneumonia caused by Sendai virus when treated with low doses of mAb directed to the CD3 Ag. The protective mechanism is not due to an accelerated Sendai virus-specific Th cell, CTL, or antibody response but to a strong NK cell response via the in vivo induction of lymphokines. Antibodies directed against the NK1.1 and asialo GM1 marker totally reversed the protective effect of anti-CD3 treatment. In vivo treatment with rIL-2 also induced NK activity and induced antiviral protection. Treatment with anti-CD3 protects when given in a narrow time window (1 day before until 1 day after Sendai virus inoculation), indicating that NK activity is protective in the early phase of virus infection.     

A protective monoclonal anti-idiotypic vaccine to lethal Semliki Forest virus infection in BALB/c mice.

Two monoclonal anti-idiotypic antibodies (ab2 MAbs), designated 1.13A112 (immunoglobulin G type 2a [IgG2a]) and 1.13A321 (IgG1), were prepared against Semliki Forest virus (SFV)-neutralizing ab1 MAb UM 1.13. They were identified in hybridoma supernatant fluid by their capacity to block UM 1.13-mediated neutralization of SFV. Although the neutralization-blocking capacities of the ab2 MAbs did not differ, only 1.13A321 evoked SFV-neutralizing ab3 antibodies upon intracutaneous and subcutaneous immunization of BALB/c mice with 1.13A321 chemically cross-linked to keyhole limpet hemocyanin and combined with the adjuvant Quil A. SFV-neutralizing ab3 antibodies appeared in serum within 10 days after primary immunization, and neutralizing antibody titers could be as high as 1/1,000 at day 35. All mice who had developed SFV-neutralizing antibodies upon anti-idiotypic immunization survived an otherwise lethal challenge with virulent SFV. However, induction of SFV-neutralizing ab3 antibodies by ab2 MAb 1.13A321 proved to be genetically restricted to BALB/c mice; even haplotype-identical (H-2d) DBA/2 mice did not respond, and consequently those animals died after infection with virulent SFV.     

Genetic resistance to lethal Sendai virus pneumonia: virus replication and interferon production in C57BL/6J and DBA/2J mice

Resistant C57BL/6J and susceptible DBA/2J mice were exposed to aerosols of Sendai virus and killed at intervals to 12 days. Lungs were removed and assayed for infectious virus and interferon. Mean virus titers were 6 to 400 times higher in DBA/2J mice than in C57BL/6J mice 3 to 10 days after exposure. Mean interferon titers were 10 to 140 times higher in DBA/2J mice than in C57BL/6J mice 4 to 7 days after exposure. These results suggest that genetic resistance to the lethal effects of Sendai virus is expressed through control of viral replication within the first 72 hours of infection and that early expression of inherited resistance is not regulated by interferon.     

Human susceptibility and resistance to Norwalk virus infection

Infectious diseases have influenced population genetics and the evolution of the structure of the human genome in part by selecting for host susceptibility alleles that modify pathogenesis. Norovirus infection is associated with approximately 90% of epidemic non-bacterial acute gastroenteritis worldwide. Here, we show that resistance to Norwalk virus infection is multifactorial. Using a human challenge model, we showed that 29% of our study population was homozygous recessive for the alpha(1,2)fucosyltransferase gene (FUT2) in the ABH histo-blood group family and did not express the H type-1 oligosaccharide ligand required for Norwalk virus binding. The FUT2 susceptibility allele was fully penetrant against Norwalk virus infection as none of these individuals developed an infection after challenge, regardless of dose. Of the susceptible population that encoded a functional FUT2 gene, a portion was resistant to infection, suggesting that a memory immune response or some other unidentified factor also affords protection from Norwalk virus infection.     

Experimental Sendai virus infection in laboratory rats. II. Pathology and immunohistochemistry

Intranasal inoculation of 5 to 8 week old specific pathogen-free Sprague-Dawley rats with 5 X 10(3) egg infectious doses of Sendai virus resulted in severe rhinitis, bronchiolitis and alveolitis. The most severe rhinitis occurred on postinoculation (PI) days 4-6, and pneumonia on day 4. Rhinitis and pneumonia persisted to PI day 21, with peribronchial lymphoid infiltration detectable at PI day 42. Immunohistochemical studies showed that Sendai virus antigens were present primarily in columnar epithelial cells of the respiratory mucosa of the nasal cavity and in bronchiolar and alveolar epithelium. Antigen was first detectable at PI day 1, was most prominent at days 3-4 and was undetectable after day 7. More antigen could be seen in the nasal mucosa than in the lung at any stage in the infection. These studies show that Sendai virus by itself is capable of evoking severe, although transient, rhinitis and pneumonia in laboratory rats free of other significant pathogens.     

A familial syndrome of susceptibility to chronic active Epstein-Barr virus infection.

In two members of a family (daughter and father) active Epstein-Barr virus (EBV) infections persisted over periods of 4 and 3 years respectively (possibly 10 years in the father). Both had persistent splenomegaly and occasional bouts of unexplained fever but lived otherwise normal lives. The other members of the family (mother and son) were healthy. The titres of antibody to the EBV viral capsid antigen (VCA) and early antigen (EA) were extremely high in the daughter''s blood, whereas the titres of antibody to the Epstein-Barr nuclear antigen were low in the daughter''s blood and undetectable in the father''s. Target cells of the EBV infection that were obtained from the daughter''s blood were established in culture with great difficulty and showed increased expression of VCA and EA. Other immunologic investigations in the two patients revealed that the ratio of helper to suppressor T lymphocytes was inverted, natural killer-cell activity was abnormally low, lymphocyte responses to certain mitogens were depressed and there was a serum factor blocking mitogen-induced transformation. The possibility that the patients'' unusual susceptibility to EBV infection represented an inherited syndrome (perhaps X-linked) is discussed.     

Dipeptidyl peptidase I-dependent neutrophil recruitment modulates the inflammatory response to Sendai virus infection

The role of innate immunity in the pathogenesis of asthma is unclear. Although increased presence of neutrophils is associated with persistent asthma and asthma exacerbations, how neutrophils participate in the pathogenesis of asthma remains controversial. In this study, we show that the absence of dipeptidyl peptidase I (DPPI), a lysosomal cysteine protease found in neutrophils, dampens the acute inflammatory response and the subsequent mucous cell metaplasia that accompanies the asthma phenotype induced by Sendai virus infection. This attenuated phenotype is accompanied by a significant decrease in the accumulation of neutrophils and the local production of CXCL2, TNF, IL-1beta, and IL-6 in the lung of infected DPPI-/- mice. Adoptive transfer of DPPI-sufficient neutrophils into DPPI-/- mice restored the levels of CXCL2 and enhanced cytokine production on day 4 postinfection and subsequent mucous cell metaplasia on day 21 postinfection. These results indicate that DPPI and neutrophils play a critical role in Sendai virus-induced asthma phenotype as a result of a DPPI-dependent neutrophil recruitment and cytokine response.     

Trixacarus caviae infection of guinea pigs with genetically determined differences in susceptibility to Trichostrongylus colubriformis infection

Guinea pigs with genetically determined resistance or susceptibility to infection with the nematode parasite Trichostrongylus colubriformis were allowed to become infected with the sarcoptid mite Trixacarus caviae. Compared with nematode-susceptible guinea pigs, nematode-resistant animals had larger populations of mites and developed a more severe dermatitis, with greater mast cell hyperplasia and many more infiltrating eosinophils. The results suggest that animals bred for resistance to one parasite may have greater susceptibility to other parasites.