Therapeutic effectiveness of bonafton and rimantadine in influenza

The therapeutic effectiveness of bonaphthone and rimantadine was studied by treatment of 439 patients with influenza between 18 and 21 years of age (bonaphthone 94, controls 105, rimantadine 120, controls 120). No therapeutic effectiveness of bonaphthone was established in the study. When rimantadine was given to the patients from the 1st day of the disease, shorter intervals of normalization of the temperature, disappearance of toxicity and catarrhal symptoms were observed than in patients treated with symptomatic drugs. During the period of rimantadine therapy the rate of findings the influenza antigen in smears from the nasal mucosa was lower, but after termination of the course of treatment the antigen was found twice as frequently as in the control group. With the positive therapeutic effect in patients treated with rimantadine, the diagnostic rise of antibody in this group was observed in a lower per cent of cases than in the control group (13 and 20%, respectively). The results of immunofluorescent and serological studies indicate a possible virus reproduction-inhibiting effect of rimantadine. This, however, requires further study. On the basis of the above observations rimantadine may be recommended for treatment of patients with influenza.     

In vivo anti-influenza virus activity of Kampo (Japanese herbal) medicine "sho-seiryu-to"--stimulation of mucosal immune system and effect on allergic pulmonary inflammation model mice

When BALB/c mice were treated with a Kampo (Japanese herbal) medicine "Sho-seiryu-to (SST)" (1 g/kg, 10 times) orally from 7 days before to 5 days after the infection and infected with mouse-adapted influenza virus A/PR/8/34 by nasal-site restricted infection, SST caused increment of the influenza virus hemagglutinin-specific IgA antibody secreting cells in nasal lymphocyte but not in Peyer's patch lymphocyte at 6 days after infection in comparison with water-treated mice. Oral administration of SST also augmented IL-2 receptor beta chain+ (activated) T-cell in Peyer's patch lymphocyte, but not in the nasal lymphocyte. We previously reported that SST showed potent anti-influenza virus activity through augmentation of the antiviral IgA antibody titer in the nasal and broncho-alveolar cavities of the mice (T. Nagai and H. Yamada, 1994, Int. J. Immunopharmacol. 16, 605-613). These results suggest that oral administration of SST shows anti-influenza virus activity in the nasal cavity by activation of T-cell in Peyer's patch lymphocyte and stimulation of production of anti-influenza virus IgA antibody in nasal lymphocyte. When ovalbumin-sensitized allergic pulmonary inflammation model mice were administered orally with SST (1 g/kg) from 8 days before (11 times) or from 2 h after (4 times) to 4 days after the infection and infected with mouse-adapted influenza virus A/PR/8/34, replications of the virus in the both nasal and broncho-alveolar cavities or only nasal cavity were significantly inhibited at 5 days after infection in comparison with water-treated control by augmenting antiviral IgA antibody, respectively. These results suggest that SST is useful for both prophylaxis and treatment of influenza virus infection on patients with allergic pulmonary inflammation, such as bronchial asthma.     

Induction of leaves directly from leaves in the maize mutant Lax midrib1-O

BACKGROUND: Asthma exacerbations are closely associated with respiratory virus infections. However, the pathophysiological consequences of such infections in asthma are largely unclear. OBJECTIVE: To examine the effect of rhinovirus 16 (RV16) infection on airway hypersensitivity to histamine, and on interleukin-8 (IL-8) in nasal lavage. METHODS: Twenty-seven non-smoking atopic, mildly asthmatic subjects participated in a placebo-controlled, parallel study. A dose of 0.5-2.9 x 10(4) TCID50 RV16 or placebo was nasally administered. Cold symptoms were recorded by questionnaire throughout the study. Histamine challenges were performed at entry, and on days 4 and 11 after inoculation. Nasal lavages were obtained at entry, and on days 2 and 9. The response to histamine was measured by PC20 (changes expressed as doubling doses: DD) IL-8 levels were obtained by ELISA, and were expressed in ng/ml. RESULTS: RV infection was confirmed by culture of nasal lavage and/or by antibody titre rise in each of the RV16-treated subjects. Among the 19 RV 16-treated subjects, eight developed severe cold symptoms. Baseline FEV1, did not change significantly during the study in either treatment group (P = 0.99). However, in the RV16-treated subjects there was a decrease in PC20 at day 4, which was most pronounced in those with a severe cold (mean change +/- SEM: -1.14 +/- 0.28 DD, P = 0.01). In addition, IL-8 levels increased in the RV16 group at days 2 and 9 (P < 0.001). The increase in nasal IL-8 at day 2 correlated significantly with the change in PC20 at day 4 (r = -0.48, P = 0.04). CONCLUSION: We conclude that the severity of cold, as induced by experimental RV16 infection, is a determinant of the increase in airway hypersensitivity to histamine in patients with asthma. Our results suggest that this may be mediated by an inflammatory mechanism, involving the release of chemokines such as IL-8.     

Prophylactic effect of bovine anti-Cryptosporidium hyperimmune colostrum immunoglobulin in healthy volunteers challenged with Cryptosporidium parvum

Bovine hyperimmune anti-Cryptosporidium colostrum immunoglobulin (BACI) decreases the intensity of Cryptosporidium parvum infection in vitro. We investigated the prophylactic effect of BACI in healthy adults challenged with C. parvum. After we established an oocyst dose that resulted in 100% infection in four volunteers (baseline group), 16 volunteers were randomized to receive (1) BACI prior to C. parvum challenge (BACI group) and a nonfat milk placebo 30 minutes later, (2) BACI prior to and 30 minutes after challenge (reinforced BACI group), or (3) nonfat milk placebo prior to and 30 minutes after challenge. Subjects received BACI (10 g) or nonfat milk placebo three times a day for a total of 5 days and were followed for clinical symptoms and oocyst excretion for 30 days. A trend toward less diarrhea (P = .08) was observed for subjects receiving BACI in comparison with occurrences in placebo recipients. Subjects receiving BACI or nonfat milk placebo had a 100-fold reduction in oocyst excretion as compared with excretion in the baseline group.     

Study of the sensitivity of different strians of the influenza A2 virus of rimantadine

The sensitivity of different influenza A2 (H3N2) virus strains to rimantadine in ovo was studied. The reference strains of influenza virus A/Hong Kong/1/68, A/England/42/72, A/Scotland/840/74 as well as new epidemic strains isolated in the USSR and Mongolia in 1974-1975 antigenically related to influenza A/Port Chalmers/1/73 virus were found to be sensitive to rimantadine.     

Susceptibilities to rimantadine of influenza A/H1N1 and A/H3N2 viruses isolated during the epidemics of 1988 to 1989 and 1989 to 1990

Clinical isolates of influenza A viruses identified during outbreaks in two winters were tested for their rimantadine susceptibilities by an enzyme-linked immunosorbent assay modified from that described previously by Belshe et al. (R. B. Belshe, B. Burk, F. Newman, R. L. Cerruti, and I. S. Sim, J. Virol. 62:1508-1512, 1988). The infectivity titer and the 50% inhibitory concentration of rimantadine were calculated for each virus. Of 105 influenza virus A isolates tested, 28 influenza A/H1N1 isolates from the 1988 and 1989 outbreak and 77 influenza A/H3N2 isolates from the outbreak in following year, were susceptible to the antiviral action of rimantadine.     

Evaluation of anti-influenza effects of camostat in mice infected with non-adapted human influenza viruses

The anti-influenza effects of camostat, a serine protease inhibitor, on in vivo influenza infections were evaluated. Mice which received non-adapted human influenza viruses intranasally, developed a reproducible infection with very low mortality. The infection was readily detected by the recovery of the virus from an oropharyngeal swab. Five-week-old ICR mice received intraperitoneal injections of saline (control), amantadine (known positive drug), or camostat, after infection with influenza A/Taiwan/1/86 virus. Virus detection was performed on day 1, 2, 3, 5, and 7 of postinfection. Both camostat and amantadine were effective in ameliorating mouse influenza. On day 5, mice injected with camostat (45%) or amantadine (50%) showed a lower virus secreting rate than those receiving saline (90%). Additionally, camostat showed strong anti-influenza effects on an amantadine-resistant type A virus and a type B virus infection in vitro. The results show that blocking the hemagglutinin cleavage is an effective target for development of an anti-influenza agent. They also demonstrate that virus detection from the oropharynx of mice, infected with non-adapted virus, is a useful in vivo influenza model.     

A containing prosthesis in the treatment of dilated myocardiopathy

OBJECTIVE: The placebo-controlled, randomized, double-blind study was performed to investigate dose-related effects of oxymetazoline on olfactory function during the course of the spontaneously occurring cold. METHODS: Drug effects were assessed using olfactory/ trigeminal event-related potentials (ERPs) and psychophysical measures (intensity ratings, odor discrimination, butanol threshold); nasal volume was monitored by means of acoustic rhinometry. The investigation was performed in 36 subjects (mean age 24.6 years). The subjects were assigned to treatment groups A, B or C (three groups with 12 subjects each; six women and six men per group). All the subjects received placebo on the left side; on the right side, group A subjects received placebo and group B and C subjects received 0.25 mg x ml(-1) and 0.5 mg x ml(-1) oxymetazoline, respectively. After onset of the rhinitis (day 0) measurements were performed on days 2, 4, 6 and 35. RESULTS: Oxymetazoline clearly produced an increase in nasal volume. However, during the 2-h observation period, effects produced by the two dosages were not significantly different. Despite the increase in nasal volume, oxymetazoline produced only an increase of the overall intensity of H2S stimuli; it had no systematic effect on other measures of olfactory or trigeminal function. In addition, after all the subjects had recovered from the cold, oxymetazoline had no significant main effect on olfactory/trigeminally mediated sensations. CONCLUSIONS: Oxymetazoline appeared to have neither negative nor major positive effects on intranasal chemosensory function. It is hypothesized that oxymetazoline needs to be applied locally to the area of the olfactory cleft in order to significantly improve olfaction during the course of the common cold.     

Inhibitory effects of recombinant manganese superoxide dismutase on influenza virus infections in mice

The oxygen free-radical scavenger recombinant human manganese superoxide dismutase (MnSOD) was studied for its effects on influenza virus infections in mice when used alone and in combination with ribavirin. Mice challenged with influenza A/NWS/33 (H1N1) virus were treated parenterally in doses of 25, 50, and 100 mg/kg of body weight per day every 8 h for 5 days beginning at 48 h post-virus exposure. An increase in mean day to death, lessened decline in arterial oxygen saturation, and reduced lung consolidation and lung virus titers occurred in the treated animals. To determine the influence of viral challenge, experiments were run in which mice were infected with a 100 or 75% lethal dose of virus and were treated intravenously once daily for 5 days beginning 96 h after virus exposure. Weak inhibition of the mortality rate was seen in mice receiving the high viral challenge, whereas significant inhibition occurred in the animals infected with the lower viral challenge, indicating that MnSOD effects are virus dose dependent. To determine if treatment with small-particle aerosol would render an antiviral effect, infected mice were treated by this route for 1 h daily for 5 days beginning 72 h after virus exposure. A dose-responsive disease inhibition was seen. An infection induced by influenza B/Hong Kong/5/72 virus in mice was mildly inhibited by intravenous MnSOD treatment as seen by increased mean day to death, lessened arterial oxygen saturation decline, and lowered lung consolidation. MnSOD was well tolerated in all experiments. A combination of MnSOD and ribavirin, each administered with small-particle aerosol, resulted in a generally mild improvement of the disease induced by the influenza A virus compared with use of either material alone.     

Safety, pharmacokinetics, and antiretroviral activity of intravenous 9-[2-(R)-(Phosphonomethoxy)propyl]adenine, a novel anti-human immunodeficiency virus (HIV) therapy, in HIV-infected adults

9-[2-(R)-(Phosphonomethoxy)propyl]adenine (PMPA) is a nucleotide analogue with potent antiretroviral activity in vitro and in simian models. A randomized, double-blind, placebo-controlled, dose-escalation clinical trial of intravenous PMPA monotherapy was conducted in 20 human immunodeficiency virus (HIV)-infected adults with CD4 cell counts of >/=200 cells/mm3 and plasma HIV RNA levels of >/=10,000 copies/ml. Two dose levels were evaluated (1 and 3 mg/kg of body weight/day). Ten subjects were enrolled at each dose level (eight randomized to receive PMPA and two randomized to receive placebo). On day 1, a single dose of PMPA or placebo was administered by intravenous infusion. Beginning on study day 8, PMPA or placebo was administered once daily for an additional 7 consecutive days. All subjects tolerated dosing without significant adverse events. Mean peak serum PMPA concentrations were 2.7 +/- 0.9 and 9.1 +/- 2.1 microgram/ml in the 1- and 3-mg/kg cohorts, respectively. Serum concentrations declined in a biexponential fashion, with a terminal half-life of 4 to 8 h. At 3 mg/kg/day, a single infusion of PMPA resulted in a 0.4 log10 median decline in plasma HIV RNA by study day 8. Following 7 consecutive days of study drug administration thereafter, the median changes in plasma HIV RNA from baseline were -1.1, -0.6, and 0.1 log10 in the 3-mg/kg/day, 1-mg/kg/day, and placebo dose groups, respectively. Following the final dose in the 3-mg/kg/day cohort, the reduction in HIV RNA was sustained for 7 days before returning toward baseline. Further studies evaluating an oral prodrug of PMPA are under way.     

Replication of influenza virus in organ cultures of human and simian urogenital tissues and human foetal tissues

A survey of human adult tissues in organ cultures showed that influenza viruses (A/Moscow/1019/65 (h2n2) or a recombinant virus virulent for man (PR/8-A/England/939/69 Clone 7a(H3N2)) could infect uterus, bladder and conjunctiva but not oesophagus under the conditions employed; simian bladder and uterus were also susceptible. These results were similar to those already described for corresponding ferret tissues. Organ cultures of human foetal nasal mucosa, trachea, oesophagus, small and large intestine, and bladder consistently supported replication over 4 days or more with high virus yields. Lung, conjunctiva and umbilical cord were less consistently susceptible and gave lower yields. Placenta and kidney cultures allowed replication of virus in one of 8 and one of 4 experiments respectively, the yields being low and of short duration. Organ cultures of neural tissue (meninges and brain), lymphopoietic tissue (spleen, liver and thymus) and amnion did not support significant viral replication. The results are discussed in relation to possible infection of the foetus in utero with influenza virus.     

4-Guanidino-2,4-dideoxy-2,3-dehydro-N-acetylneuraminic acid is a highly effective inhibitor both of the sialidase (neuraminidase) and of growth of a wide range of influenza A and B viruses in vitro

The sialidase (neuraminidase) inhibitor 4-guanidino-2,4-dideoxy-2,3-dehydro-N-acetylneuraminic acid (4-guanidino-Neu5Ac2en) has been examined for the ability to inhibit the growth of a wide range of influenza A and B viruses in vitro in comparison with amantadine, rimantadine, and ribavirin. 4-Guanidino-Neu5Ac2en inhibited plaque formation by laboratory-passaged strains of influenza A and B viruses, with 50% inhibitory concentrations ranging from 0.005 to 0.014 microM. A wider range of values (0.02 to 16 microM) was obtained with more recent clinical isolates, but in all cases 4-guanidino-Neu5Ac2en inhibited influenza A and B virus replication at lower concentrations than amantadine, rimantadine, or ribavirin. Inhibition by 4-guanidino-Neu5Ac2en was not obviously affected by the passage history of the viruses or by resistance to amantadine or rimantadine. 4-Guanidino-Neu5Ac2en was a very potent inhibitor of the sialidases of all the influenza viruses examined, with 50% inhibitory concentrations ranging from 0.00064 to 0.0079 microM. No cytotoxicity was observed with 4-guanidino-Neu5Ac2en at up to 10 mM. 4-Guanidino-Neu5Ac2en therefore represents a new potent and selective inhibitor of influenza A and B virus sialidase activity and replication in vitro.     

Application of various antioxidants in the treatment of influenza

We determined the effect of the antioxidants superoxide dismutase, desferrioxamine and allopurinol on the survival of male CBA mice infected intranasally with 2-5 LD50 lung influenza virus A/Aichi/2/68. Survival for at least 20 days was observed for 45% of the mice that received 1000 U/day superoxide dismutase prepared from red blood cells on days 5, 6, 7 and 8 after infection, and 75% survival was observed for mice that received the same dose on days 4, 5, 6, 7 and 8. Desferrioxamine, 25 mg/kg per day and 100 mg/kg per day injected subcutaneously, resulted in survival rates of 5 and 0%, respectively, compared to 10% survival observed for saline-injected controls. Allopurinol at doses of 5 to 50 mg/kg per day had no effect on mouse survival. These data demonstrate the efficacy of superoxide dismutase for the protection of mice against hemorrhagic lung edema. The ineffectiveness of allopurinol suggests that the xanthine oxidase system does not play a major role in hemorrhage or lung edema and that caution is necessary when desferrioxamine is administered during an acute inflammatory process accompanied by erythrocyte lysis.     

Efficacy of brompheniramine maleate for the treatment of rhinovirus colds

We tested the efficacy of brompheniramine maleate in a large randomized, controlled trial of volunteers with experimental rhinovirus colds. Brompheniramine (12 mg) or placebo was administered at 8:00 A.M. and 8:00 P.M. for < or = 4 days after the onset of symptoms (24, 36, or 48 hours after virus challenge). During the first 3 days of treatment (the first 4 days after virus challenge), nasal secretion weights were lower for infected evaluable subjects receiving brompheniramine (n = 113) than for controls (day 1: 4.3 g vs. 6.8 g; day 2: 4.8 g vs. 7.7 g; and day 3: 3.3 g vs. 5.3 g) (P < or = .03), as were rhinorrhea scores (day 1: 0.6 vs. 0.8; day 2: 0.5 vs. 0.8; and day 3: 0.3 vs. 0.5) (P < .03), sneeze counts (day 1: 1.8 vs. 3.6; day 2: 2.1 vs. 5.1; and day 3: 1.3 vs. 3.3) (P < or = .001), and sneeze severity scores (day 1: 0.3 vs. 0.6; day 2: 0.25 vs. 0.7; and day 3: 0.2 vs. 0.4) (P < .001) (n = 112). Cough counts were lower after day 1 of treatment for the brompheniramine group than for controls (4.7 vs. 7.9) (P = .05) (day 2 after virus challenge), and other symptoms were modestly reduced or were unaffected in the brompheniramine group. Total symptom scores were also lower for the brompheniramine group than for controls on treatment days 1 (4.8 vs. 6.0) (P = .03) and 2 (4.1 vs. 5.6) (days 2 and 3 after virus challenge) (P = .003). Treatment with brompheniramine was associated with the adverse effects of somnolence (n = 3) and confusion (n = 1). Brompheniramine was efficacious treatment for the sneezing, rhinorrhea, and cough associated with rhinovirus colds.     

Immunopotentiation of local and systemic humoral immune responses by ISCOMs, liposomes and FCA: role in protection against influenza A in mice

The immunogenicity and protective efficacy of an influenza A subunit vaccine preparation administered to mice in an aqueous form, or presented as immunostimulatory complexes (ISCOMs), liposomes or with Freund's complete adjuvant (FCA), were assessed in comparative studies with live infectious virus. Both intranasal and parenteral routes of administration were assessed. An enzyme-linked immunosorbent assay (ELISA) was used to measure nasal wash and serum antibody responses in groups of unprimed mice, while protection was determined by the recovery of homologous influenza virus from mouse nasal washes and lung homogenates following challenge infection by the intranasal route. The results showed that parenteral administration of the influenza antigen preparations induced variable levels of both local and systemic antibodies at weeks 3, 7 and 22 postimmunization. Although the overall greatest levels of antibody and protection were elicited in mice following live virus infection, formulation of influenza surface haemagglutinin (HA) and neuraminidase (NA) proteins into ISCOMs elicited high and persistent antibody responses and provided relatively good protection of the upper and lower respiratory tracts of these animals. The results also show a relatively poor effect of the subunit antigen preparations in promoting humoral immune responses and protection irrespective of the nature of their presentation, when given by the intranasal route.     

Influenza A virus infection increases IgE production and airway responsiveness in aerosolized antigen-exposed mice

BACKGROUND: Respiratory viral infection is known clinically to promote sensitization to antigen inhalation and the development of asthma. OBJECTIVE: The purpose of this investigation was to determine whether influenza type A virus infection enhances inhalation sensitization and increases airway responsiveness in mice. METHODS: Mice were infected by intranasal inoculation with influenza A viruses (strains: H1N1 and H3N2) or PBS. Animals were exposed to aerosols of ovalbumin on day 3. Two weeks after ovalbumin sensitization, mice were challenged with ovalbumin aerosols; 24 hours later, airway responsiveness (AR) to inhaled methacholine, levels of ovalbumin-specific IgE, and bronchoalveolar lavage fluid (BALF) were examined. RESULTS: Neither influenza A virus (H1N1 nor H3N2) alone nor ovalbumin sensitization alone caused changes in AR or IgE. However, ovalbumin sensitization after inoculation with either influenza A virus increased AR and levels of ovalbumin-specific IgE. On BALF-cell analysis, ovalbumin sensitization after inoculation with influenza virus A increased the number of lymphocytes but not the number of eosinophils. No difference in AR or IgE levels was observed between the 2 strains of influenza A viruses. Immmunostaining of BALF cells showed an increase in T cells, especially CD8(+) cells, with ovalbumin sensitization after inoculation with influenza virus A. CONCLUSION: Infection by influenza A virus enhances sensitization to inhaled antigens and airway responsiveness in mice by means of mechanisms including CD8(+) cells and antigen-specific IgE.     

Experimental encephalomyocarditis virus infection in pigs

A field isolate of Encephalomyocarditis (EMC) virus was inoculated intravenously into 8 pigs. Four animals died at post inoculation day (PID) 2, the remaining being sacrificed at PID 5, 7, 11 and 15. Two control, in-contact pigs were sacrificed at PID 19. Virus was isolated from leucocytes and nasal swabs until PID 4, from rectal swabs until PID 2 and, in the pigs found dead at PID 2, from several organs. EMC virus was further isolated from brain and spleen of the pig sacrificed at PID 7. One of the 2 control pigs became infected: virus was isolated from nasal swabs at days 6 and 7 and from leucocytes at day 4 of the experiment. Serum-neutralizing (SN) antibody was detected in the injected pigs starting from PID 4; two days later, it was also revealed in the infected, in-contact control. To our knowledge, this is the first report of an experimental transmission of EMC virus infection in pigs by contact exposure.     

Duration of antiviral prophylaxis during nursing home outbreaks of influenza A: a comparison of 2 protocols

BACKGROUND: We performed a randomized trial of 2 protocols guiding the duration of antiviral chemoprophylaxis during outbreaks of influenza A in a rural, 700-bed nursing home for veterans and their spouses with 14 nursing units in 4 buildings. METHODS: Half of all residents volunteered to participate. Nursing units were randomized, and the effectiveness of short-term (minimum, 14 days and 7 days without the onset of a case in the building) vs long-term (minimum, 21 days and 7 days without the onset of a case in the 4-building facility) prophylaxis was compared using amantadine hydrochloride in the influenza seasons of 1991-1992 and 1993-1994 and rimantadine hydrochloride in the influenza season of 1994-1995. A "case" is defined as an incident of a respiratory tract illness and the isolation of an influenza virus organism. We compared the number of cases after the discontinuation of short- vs long-term chemoprophylaxis. Prospective surveillance identified residents with new respiratory tract symptoms, and specimens for viral cultures were obtained even in the absence of temperature elevation. RESULTS: We documented influenza A virus activity during 3 seasons (32, 68, and 12 patients, respectively). During the 1991-1992, 1993-1994, and 1994-1995 influenza seasons, the patients on 11 floors were assigned to receive short-term chemoprophylaxis and those on 10 floors were assigned to long-term chemoprophylaxis. Only in 1993-1994 did chemoprophylaxis extend beyond 14 or 21 days when new cases continued beyond 14 days. Amantadine-resistant strains were circulating at that time. None of the participants in the prospective, controlled study had influenza develop after the termination of short- or long-term chemoprophylaxis. CONCLUSION: Antiviral chemoprophylaxis can be administered for the longer duration of 14 days or, in the absence of new culture-confirmed illness in the nursing building, for 7 days.     

Antineuraminidase serum antibodies in natural influenza A and immunization with influenza vaccines

Parallel HI and virus-elution-from-erythrocytes-inhibition (a simplified method for titration of neuraminidase antibody) tests were used for examinations of 1117 blood serum specimens from 440 adults and children under study, 5250 single serum specimens from healthy subjects from birth to 65 years of age, 38 paired serum specimens from children who experienced influenza A/Texas/1/77 disease in the epidemic of 1979-1980, and 590 paired serum specimens from subjects immunized with influenza vaccines. In 7%-23% of influenza patients and immunized subjects antibody rise was observed to only one of the influenza A virus surface antigens, hemagglutinin or neuraminidase. The protective activity of antibody to influenza A virus neuraminidase was as good as that of antihemagglutinins. Both kinds of antibody interacted in protection against the disease. Antineuraminidase antibody was found to affect the decrease in severity of the infectious process in natural infection with influenza A. The formation of immunological memory in the system of synthesis of antihemagglutinins and antineuraminidase antibodies was shown to have features in common. The pattern of heterologous immune responses in immunized subjects and patients with influenza showed all antigenic varieties of neuraminidase N2 as well as neuraminidases N1 and N2 to share common cross-reacting determinants.