Propagation of Chandipura virus in chick embryos.

Stocks of three Indian Chandipura virus (CHPV) isolates; one isolate from an adult febrile case in 1965 from Chandipura town, Maharashtra, and two isolates from two pediatric encephalitis cases from Andhra Pradesh, 2003 were inoculated in 10-day-old chick embryos by allantoic route. All three virus isolates replicated in chick embryos showing titre of log 10(12) to log 10(13) EID50. The results demonstrated that chick embryos are susceptible to CHPV and virus grows to high titres in this system. Therefore chick embryos can be used as an alternative host system for cultivation and isolation of CHPV as they are less expensive than laboratory animals and have several other advantages over cell cultures. Also this system can be used for the development of vaccine and diagnostic reagents.

Influenza surveillance in Pune, India, 2003.

Influenza surveillance was conducted in Pune, India in 2003. A total of 573 throat swabs/ nasal swabs (TS/NS) and 190 nasopharyngeal aspirates (NPA) were collected from 763 in- and out-patients who were mostly children aged 0-16 years. TS/NS (507/573) and NPA (42/190) specimens were processed in MDCK cell cultures and identified with the hemagglutination inhibition test (HI). A total of 37 influenza viruses was isolated: twenty-three type A (H3N2) and 14 type B of the Yamagata lineage were isolated from 29 children and 8 adults. Three type A (H3N2) isolates were characterized as being similar to A/Panama/2007/99 like, A/Korea/770/2000 like, and B/Sichuan/379/99 like strains.

Epidemiology and control of influenza.

Influenza causes frequent epidemics and periodic pandemics, and is a major public health problem. Pandemics occurred in 1918 (swine influenza), 1957 (Asian influenza), 1968 (Hong Kong influenza) and 1977 (Russian influenza) due to major antigenic variation of the type A influenza virus. Frequent epidemics occur after pandemics as a result of minor antigenic variation of the pandemic virus strains. Minor antigenic variant strains of type A (H1N1), A (H3N2) and type B influenza viruses are currently circulating globally, causing frequent epidemics. The World Health Organization (WHO) has established a network of National Influenza Centres all over the world to study the epidemiology and ecology of influenza, and collaborating centres for updating the influenza vaccines and other research activities. As a part of this programme, it has set up the WHO Flunet for disseminating updates on the global influenza situation, current vaccines and antiviral drugs. Some National Influenza Centres in India have investigated and reported pandemics and epidemics caused by global influenza virus strains during the past 50 years. There is a need to expand influenza surveillance in our country, as only a few centres are conducting these studies.

Growth of respiratory syncytial virus in mink lung epithelial cells.

Mink lung epithelial cells (Mv-1-Lu) were tested for their ability to support the growth and serial passage of respiratory syncytial virus (RSV) in vitro. Indian isolates of RSV induced distinctive cytopathic effect with typical rounding of cells followed by detachment with more than 50 per cent cells showing bright fluorescence using anti-RSV monoclonal antibodies in immunofluorescence test. Serial passage of RSV was possible in Mv-1-Lu cells without loss of sensitivity of the cells for virus growth. Titration of cell associated virus and virus released in the supernatant indicated that 60 per cent of the virus was released in the supernatant, and 40 per cent remained cell associated. Transmission electron microscopic studies of negatively stained RSV particles and ultra-thin sections of RSV infected Mv-1-Lu cells showed roughly spherical particles with club shaped projections, budding from the cytoplasmic membrane. These results indicate that Mv-1-Lu cell line is suitable for the growth and propagation of RSV.

Isolation of recent variant influenza types A(H3N2), A (H1N1) & B strains in Pune, India.

A total of 293 patients with influenza like illness were investigated during the course of continuous surveillance on influenza in Pune, India in 2000. The throat/nasal swab specimens collected from these patients were inoculated in MDCK cell culture and influenza types A(H3N2), A(H1N1) and type B strains were isolated. They were identified as similar to the recently prevalent variant strains; A/Sydney/05/97(H3N2), A/New Caledonia/20/99(H1N1) and B/Sichuan/379/99. The latter two were the new variant strains reported for the first time in Pune. It is important to note that A(H1N1) strains were isolated in Pune during 2000 after a gap of 10 yr.

Seroepidemiology of influenza in Pune, India.

BACKGROUND & OBJECTIVES: Influenza viruses cause frequent epidemics and periodic pandemics throughout the world due to antigenic variations. Serological data can be useful to determine the disease burden and population immunity and for predicting the likelihood of occurrence and potential severity of subsequent epidemics. We undertook a serological analysis of antibodies against ten influenza virus strains in Pune, India. METHODS: Haemagglutination inhibition (HI) test was done on 619 sera collected between 1997-99 during an age-stratified serosurvey in Pune, India against 10 strains of influenza virus. Overall prevalence and spectrum of HI antibodies against these strains was determined. RESULTS: Antibodies to at least one influenza virus strain was seen in 62 per cent (116/188) of the sera from individuals in the age group 5-15 yr, 77 per cent (85/111) in sera from 16-25 yr, 78 per cent (93/119) from 26-35 yr, 84 per cent (77/92) from 36-45 yr and 93 per cent (101/109) in sera from individuals aged > 45 yr. The antibody spectrum progressively increased with age. Antibodies to the pandemic strain A(H2N2) were absent in the age groups < 25 yr. INTERPRETATION & CONCLUSION: The results indicate that influenza virus infection occurs in a large proportion of individuals in our community and may be responsible for a considerable amount of morbidity and mortality. The study also demonstrates the absence of antibody to A/Singapore/1/57 (H2N2) strain in younger persons < 25 yr of age. The potential of its reintroduction cannot be ruled out as H2 variants are circulating in wild birds and population immunity in humans is decreasing.

Isolation of recent variant influenza types A (H3N2) & B strains in Pune, India during 1998.

A total of 456 patients with influenza like illness were investigated during the course of continuous surveillance on influenza in Pune, India in 1998. The throat and nasal swab specimens collected from these patients were processed in MDCK cell culture. Influenza type A (H3N2) and type B strains were isolated in MDCK cell culture. They were identified as similar to the recently prevalent globally circulating variant strains; A/Sydney/05/97 (H3N2) and B/Harbin/07/94.

Isolation of the new variant influenza A (H3N2) strains during an outbreak in Pune, February, 1996.

During January-February, 1996, an outbreak of influenza-like illness occurred in Pune. The throat and nasal swabs collected from the patients during this outbreak were processed in MDCK and LLC-MK2 cell cultures and influenza A(H3N2) viruses were isolated. They were identified as being similar to the recent circulating global strains A/Johannesburg/33/94 and A/Wuhan/359/95.