Inactivated hepatitis A virus vaccines

Hepatite A: soroprevalência e fatores associados em escolares de São Luís (MA), Brasil

OBJETIVOS: Estimar a prevalência de anticorpos contra o vírus da hepatite A (antiVHA-IgG) em escolares de 7 a 14 anos de escolas públicas e privadas e identificar fatores demográficos, socioeconômicos e sanitários associados à prevalência de antiVHA-IgG. MÉTODOS: Estudo soroepidemiológico para detecção de antiVHA-IgG, de abril de 2002 a abril de 2004, em 462 escolares de São Luís, com idades compreendidas entre 7 e 14 anos, do ensino fundamental. Participaram 30 escolas aleatoriamente selecionadas, com probabilidade proporcional ao número de alunos matriculados, sendo 23 públicas e 7 privadas. Os dados foram obtidos por meio de questionário estruturado. Para se identificar variáveis independentemente associadas à prevalência do antiVHA-IgG, foi realizada análise de regressão de Poisson múltipla, sendo estimadas as RPs ajustadas e respectivos intervalos de confiança de 95%. Somente permaneceram no modelo final aquelas variáveis associadas com a prevalência da hepatite A com p < 0,10. Foi adotado o nível de significância de 0,05 (α = 0,05). RESULTADOS: A prevalência de antiVHA-IgG foi de 64%, sendo de 71,5% nas escolas públicas e de 36,5% nas privadas. Após análise multivariável, idade de 11 a 14 anos, mais de uma pessoa por dormitório e menos de dois banheiros por domicílio foi associada a maiores prevalências de antiVHA-IgG. Maior escolaridade dos pais esteve associada à menor prevalência de antiVHA-IgG. CONCLUSÕES: A hepatite A é endêmica nos escolares de São Luís, com taxa de prevalência semelhante àquela encontrada em outras regiões do país com condições socioeconômicas e sanitárias similares. Fatores historicamente associados à maior prevalência da hepatite A foram também identificados nesta população.

Experimental hepatitis A virus (HAV) infection in cynomolgus monkeys (Macaca fascicularis): evidence of active extrahepatic site of HAV replication

This work studied the replication sites of hepatitis A virus (HAV) in cynomolgus monkeys (Macaca fascicularis) after intravenous inoculation. The cynomolgus monkeys were inoculated with the Brazilian hepatitis A virus strain (HAF-203). Monkeys were euthanized on days 15, 30, 45 and 60 postinoculation (pi). Liver samples, submandibular salivary gland, mesenteric lymph node and tonsils were removed for virological and pathological evaluation. Immunofluorescence analyses on liver and salivary gland sections using confocal laser scanning microscopy revealed the presence of HAV antigen (HAV Ag). The presence of HAV genome was monitored by real-time PCR. The HAV RNA was detected at 7 days postinoculation (dpi), concomitantly in serum, saliva and faeces. The highest HAV viral load was observed in faeces at 15 dpi (10(5) copies/ml), followed by serum viral load of 10(4) copies/ml at 20 dpi and saliva viral load of 10(3 )copies/ml at 7 dpi. The animals showed first histological and biochemical signs of hepatitis at 15 dpi. The HAV antigen (Ag) was present from day 7 until day 60 pi in the liver and salivary glands. The HAV replicative intermediate was also detected in the liver (4.5 x 10(4) copies/mg), salivary glands (1.9 x 10(3) copies/mg), tonsils (4.2 x 10(1) copies/mg) and lymph nodes (3.4 x 10(1) copies/mg). Our data demonstrated that the salivary gland as an extrahepatic site of early HAV replication could create a potential risk of saliva transmitted infection. In addition, the cynomolgus monkey was confirmed as a suitable model to study the pathogenesis of HAV human infection.

Genetic analysis of HAV strains in Tunisia reveals two new antigenic variants

To evaluate the genetic variability of hepatitis A virus (HAV) isolates in Tunisia, serum samples were collected from 99 patients in different Tunisian areas in 2003 containing 92 cases with acute hepatitis, five with severe acute hepatitis and two with fulminant hepatitis. The entire VP1 gene was amplified and sequenced. Sequences were then aligned and a phylogenetic analysis was performed. Additionally, the amino acid (aa) sequence of the VP1 was determined. The analysis of Tunisian HAV isolates revealed that all the isolates were sub-genotype IA with 96.4%-99.8% of identity and showed the emergence of two novel antigenic variants. The Tun31-03 antigenic variant, with a 38 aa deletion containing Met156, Val171, Leu174 and Ala176 and located between 150 and 187 aa of the VP1 protein where neutralization escape mutations, was found. The second antigenic variant, Tun36-03, was isolated from a patient with fulminant hepatitis and presented a substitution of Thr by Pro at position 10 of the VP1 protein. This amino acid is located in a peptide presenting an antigenically reactive epitope of the VP1 protein. This substitution has never been described previously.

Soroprevalência das infecções pelos vírus das hepatites A e B em Macaé, Rio de Janeiro, Brasil

As soroprevalências do anti-HAV e anti-HBc totais em dois grupos sócio-econômicos de Macaé, Rio de Janeiro, Brasil, foram estimadas em 1.100 alíquotas excedentes de soro de laboratório de análises clínicas, identificadas por sexo, idade, residência e segundo categoria da assistência médica: Sistema Único de Saúde (SUS) e serviços privados (NSUS). Apresentam-se as soroprevalências por faixa etária e os intervalos de confiança de 95%, testando-se a significância das diferenças entre o SUS e NSUS. A distribuição das soroprevalências (P) do anti-HAV (P = 88,8%; IC 95%: 86,8-90,6) e do anti-HBc (P = 15,3%; IC 95%: 13,2-17,6) evidenciou curva etária ascendente. A prevalência no SUS mostrou-se significativamente maior que no NSUS, para o VHA (chi2 = 31,15; p < 0,0001) e para o VHB (chi2 = 15,41; p < 0,0001). As altas prevalências refletem o padrão epidemiológico da infecção pelo VHA em regiões em desenvolvimento e a importância do componente sócio-ambiental. A proporção de < 5 e de > 20 anos suscetíveis lembra a necessidade de vacinação contra a hepatite A e a possibilidade de aumento da ocorrência de casos graves da doença. A alta prevalência do VHB entre os adolescentes sugere reflexões sobre a importância da vacinação destes grupos. Estes resultados servem de alerta aos profissionais da saúde quanto à observância de normas de biossegurança.

Evaluation of the timing of the booster injection after a primary vaccination against hepatitis A

To evaluate the long-term efficacy and the timing of booster injection of a lyophilized, inactivated hepatitis A vaccine (HAV), we studied the acquired anti-hepatitis A virus titres in 45 subjects who received either two or three doses of the vaccine. With three doses > or = 0.5 microgram administered at 0, 1 and 6 months, antibody titres increased to approximately half those seen in people with a history of natural hepatitis A infection. Although the titres decreased gradually, all subjects remained anti-HAV positive at least 5 years after the third injection. The geometric mean titre exceeded 100 mIU/mL, which approximated the highest titre obtainable by the inoculation of immune serum globulin. A prompt antibody reaction was seen with two doses administered 2 weeks apart, with the titres achieved being 5.6-fold the peak titres obtained by the inoculation of immune serum globulin. All 33 subjects were antibody positive 18 months after the first injection, but some became seronegative by 30 months, suggesting that a third booster dose would be desirable at 18 months.

Good immunogenicity of GBM strain inactivated hepatitis A vaccine in healthy male adults

A formalin-inactivated aluminium hydroxide adsorbed hepatitis A vaccine was evaluated in a dose-response study on 195 healthy male adults (age range: 18-31 years) in two French hospitals (Lyon, Rouen). Four doses (20, 40, 80, 160 RIA antigen units) were administered intramuscularly (i.m.) in two injections over a 6-month period. At the time of the first vaccine injection, 32 subjects (16.4%) were found positive (> 20 mIU ml-1) for HAV antibody (total Ig RIA HAVAB assay, Abbott Laboratories) and were excluded from the analysis of immunogenicity criteria. Fourteen days after the first vaccine injection, 78.1% (95% confidence interval (CI): 62-90) of seronegative subjects who received the 160 RIA antigen unit dose seroconverted with a geometric mean titre (GMT) of 43 mIU ml-1 (95% CI: 33-56). Seroconversion was 100% (95% CI: 91-100) at 1 month with a GMT of 95 mIU ml-1 (95% CI: 79-112). Statistical analysis revealed a significant dose-related effect (p < 0.0001) on GMT by multivariate regression analysis of the results after the first injection. Biological safety was evaluated and alanine aminotransferase and aspartate aminotransferase levels were similar prior to and 14 days after the first injection in the four groups. Reactions after injection were similar in the four dosage groups: 6.2% of subjects reported immediate reactions after first vaccination (feeling sick, spontaneous pain, headache), 8.9% reported local reactions at the site of injection (spontaneous pain, haematoma, local adenopathy) and 13.5% reported general reactions ('flu-like' syndrome, gastrointestinal tract disorders, fatigue, headache).(ABSTRACT TRUNCATED AT 250 WORDS)

Single dose inactivated hepatitis A vaccine: rationale and clinical assessment of the safety and immunogenicity

In comparison with the classical immunisation schedules (0-1-6 or 0-1-12 months) for hepatitis A, a 0- and 12- or a 0- and 6-month schedule would have important advantages by reducing the number of injections and discomfort and increasing scheduling convenience and patient compliance. It would be convenient if a single dose with enough antigen could protect both rapidly and for at least 12 months, when the booster dose would be given. Several clinical trials have been carried out with an inactivated hepatitis A vaccine containing 1,440 EL.U. (1 ml), according to a 0-12 and a 0-6 vaccination schedule. This hepatitis A vaccine is safe and well tolerated. It offers a rapid seroresponse: 14 days after a single dose the seroconversion is 88% (95% C.I.: 84.6-90.9). The 0-12 schedule study showed good persistence of hepatitis A virus (HAV) antibodies with a seroconversion rate of almost 95% at month 12. Booster doses given at 6 or 12 months result in a substantial rise in antibody levels; according to these antibody titres, the 1,440 EL.U. vaccine can be expected to confer comparable duration of protection as the 720 EL.U. vaccine, i.e., 10-20 years. Preliminary data show that timing of the booster may not be critical for the antibody response. In conclusion, the 1,440 EL.U. hepatitis A vaccine is safe, offers rapid seroconversion, and is highly immunogenic. The persistence of HAV antibodies until month 12 allows a certain flexibility in the administration of the booster: month 6 or 12, and a 0-12 or 0-6 schedule can increase the vaccination compliance.

Liver disease

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